diff --git a/src/Makefile.qt.include b/src/Makefile.qt.include
index 3491f07ee00..a46ddb630a2 100644
--- a/src/Makefile.qt.include
+++ b/src/Makefile.qt.include
@@ -56,6 +56,7 @@ QT_MOC_CPP = \
   qt/moc_macdockiconhandler.cpp \
   qt/moc_macnotificationhandler.cpp \
   qt/moc_modaloverlay.cpp \
+  qt/moc_netwatch.cpp \
   qt/moc_notificator.cpp \
   qt/moc_openuridialog.cpp \
   qt/moc_optionsdialog.cpp \
@@ -129,6 +130,7 @@ BITCOIN_QT_H = \
   qt/macnotificationhandler.h \
   qt/macos_appnap.h \
   qt/modaloverlay.h \
+  qt/netwatch.h \
   qt/networkstyle.h \
   qt/notificator.h \
   qt/openuridialog.h \
@@ -232,6 +234,7 @@ BITCOIN_QT_BASE_CPP = \
   qt/initexecutor.cpp \
   qt/intro.cpp \
   qt/modaloverlay.cpp \
+  qt/netwatch.cpp \
   qt/networkstyle.cpp \
   qt/notificator.cpp \
   qt/optionsdialog.cpp \
diff --git a/src/qt/bitcoingui.cpp b/src/qt/bitcoingui.cpp
index 7c22880dd1c..8f5c5aadbcc 100644
--- a/src/qt/bitcoingui.cpp
+++ b/src/qt/bitcoingui.cpp
@@ -10,6 +10,7 @@
 #include <qt/guiconstants.h>
 #include <qt/guiutil.h>
 #include <qt/modaloverlay.h>
+#include <qt/netwatch.h>
 #include <qt/networkstyle.h>
 #include <qt/notificator.h>
 #include <qt/openuridialog.h>
@@ -239,6 +240,7 @@ BitcoinGUI::~BitcoinGUI()
     MacDockIconHandler::cleanup();
 #endif
 
+    delete NetWatch;
     delete rpcConsole;
 }
 
@@ -320,6 +322,9 @@ void BitcoinGUI::createActions()
     m_load_psbt_clipboard_action = new QAction(tr("Load PSBT from &clipboard…"), this);
     m_load_psbt_clipboard_action->setStatusTip(tr("Load Partially Signed Bitcoin Transaction from clipboard"));
 
+    m_show_netwatch_action = new QAction(tr("&Watch network activity"), this);
+    m_show_netwatch_action->setStatusTip(tr("Open p2p network watching window"));
+
     openRPCConsoleAction = new QAction(tr("Node window"), this);
     openRPCConsoleAction->setStatusTip(tr("Open node debugging and diagnostic console"));
     // initially disable the debug window menu item
@@ -363,6 +368,7 @@ void BitcoinGUI::createActions()
     connect(aboutQtAction, &QAction::triggered, qApp, QApplication::aboutQt);
     connect(optionsAction, &QAction::triggered, this, &BitcoinGUI::optionsClicked);
     connect(showHelpMessageAction, &QAction::triggered, this, &BitcoinGUI::showHelpMessageClicked);
+    connect(m_show_netwatch_action, &QAction::triggered, this, &BitcoinGUI::showNetWatch);
     connect(openRPCConsoleAction, &QAction::triggered, this, &BitcoinGUI::showDebugWindow);
     // prevents an open debug window from becoming stuck/unusable on client shutdown
     connect(quitAction, &QAction::triggered, rpcConsole, &QWidget::hide);
@@ -509,6 +515,8 @@ void BitcoinGUI::createMenuBar()
         window_menu->addAction(usedReceivingAddressesAction);
     }
 
+    window_menu->addAction(m_show_netwatch_action);
+
     window_menu->addSeparator();
     for (RPCConsole::TabTypes tab_type : rpcConsole->tabs()) {
         QAction* tab_action = window_menu->addAction(rpcConsole->tabTitle(tab_type));
@@ -591,6 +599,10 @@ void BitcoinGUI::setClientModel(ClientModel *_clientModel, interfaces::BlockAndH
         // Show progress dialog
         connect(_clientModel, &ClientModel::showProgress, this, &BitcoinGUI::showProgress);
 
+        if (NetWatch) {
+            NetWatch->setClientModel(_clientModel);
+        }
+
         rpcConsole->setClientModel(_clientModel, tip_info->block_height, tip_info->block_time, tip_info->verification_progress);
 
         updateProxyIcon();
@@ -618,6 +630,9 @@ void BitcoinGUI::setClientModel(ClientModel *_clientModel, interfaces::BlockAndH
             trayIconMenu->clear();
         }
         // Propagate cleared model to child objects
+        if (NetWatch) {
+            NetWatch->setClientModel(nullptr);
+        }
         rpcConsole->setClientModel(nullptr);
 #ifdef ENABLE_WALLET
         if (walletFrame)
@@ -856,6 +871,15 @@ void BitcoinGUI::aboutClicked()
     GUIUtil::ShowModalDialogAsynchronously(dlg);
 }
 
+void BitcoinGUI::showNetWatch()
+{
+    if (!NetWatch) {
+        NetWatch = new GuiNetWatch(platformStyle, m_network_style);
+        NetWatch->setClientModel(clientModel);
+    }
+    GUIUtil::bringToFront(NetWatch);
+}
+
 void BitcoinGUI::showDebugWindow()
 {
     GUIUtil::bringToFront(rpcConsole);
@@ -1218,6 +1242,9 @@ void BitcoinGUI::closeEvent(QCloseEvent *event)
     {
         if(!clientModel->getOptionsModel()->getMinimizeOnClose())
         {
+            if (NetWatch) {
+                NetWatch->close();
+            }
             // close rpcConsole in case it was open to make some space for the shutdown window
             rpcConsole->close();
 
@@ -1411,6 +1438,9 @@ void BitcoinGUI::detectShutdown()
 {
     if (m_node.shutdownRequested())
     {
+        if (NetWatch) {
+            NetWatch->hide();
+        }
         if(rpcConsole)
             rpcConsole->hide();
         Q_EMIT quitRequested();
diff --git a/src/qt/bitcoingui.h b/src/qt/bitcoingui.h
index 0ae5f7331e2..1f8dbbd3525 100644
--- a/src/qt/bitcoingui.h
+++ b/src/qt/bitcoingui.h
@@ -28,6 +28,7 @@
 #include <memory>
 
 class ClientModel;
+class GuiNetWatch;
 class NetworkStyle;
 class Notificator;
 class OptionsModel;
@@ -150,6 +151,7 @@ class BitcoinGUI : public QMainWindow
     QAction* backupWalletAction = nullptr;
     QAction* changePassphraseAction = nullptr;
     QAction* aboutQtAction = nullptr;
+    QAction* m_show_netwatch_action = nullptr;
     QAction* openRPCConsoleAction = nullptr;
     QAction* openAction = nullptr;
     QAction* showHelpMessageAction = nullptr;
@@ -168,6 +170,7 @@ class BitcoinGUI : public QMainWindow
     QSystemTrayIcon* trayIcon = nullptr;
     const std::unique_ptr<QMenu> trayIconMenu;
     Notificator* notificator = nullptr;
+    GuiNetWatch* NetWatch = nullptr;
     RPCConsole* rpcConsole = nullptr;
     HelpMessageDialog* helpMessageDialog = nullptr;
     ModalOverlay* modalOverlay = nullptr;
@@ -293,6 +296,7 @@ public Q_SLOTS:
     void optionsClicked();
     /** Show about dialog */
     void aboutClicked();
+    void showNetWatch();
     /** Show debug window */
     void showDebugWindow();
     /** Show debug window and set focus to the console */
diff --git a/src/qt/guiconstants.h b/src/qt/guiconstants.h
index fcdf6056c95..5c6f0eb68fb 100644
--- a/src/qt/guiconstants.h
+++ b/src/qt/guiconstants.h
@@ -26,6 +26,8 @@ static const bool DEFAULT_SPLASHSCREEN = true;
 
 /* Invalid field background style */
 #define STYLE_INVALID "background:#FF8080"
+/* Background style for active search in NetWatch */
+#define STYLE_ACTIVE "background:#80FF80"
 
 /* Transaction list -- unconfirmed transaction */
 #define COLOR_UNCONFIRMED QColor(128, 128, 128)
diff --git a/src/qt/netwatch.cpp b/src/qt/netwatch.cpp
new file mode 100644
index 00000000000..58a62c1215f
--- /dev/null
+++ b/src/qt/netwatch.cpp
@@ -0,0 +1,838 @@
+// Copyright (c) 2017-2021 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#if defined(HAVE_CONFIG_H)
+#include <config/bitcoin-config.h>
+#endif
+
+#include <qt/netwatch.h>
+
+#include <qt/bitcoinunits.h>
+#include <qt/clientmodel.h>
+#include <qt/guiconstants.h>
+#include <qt/guiutil.h>
+#include <qt/networkstyle.h>
+#include <qt/optionsmodel.h>
+#include <qt/platformstyle.h>
+
+#include <chain.h>
+#include <chainparams.h>
+#include <key_io.h>
+#include <node/blockstorage.h>
+#include <primitives/transaction.h>
+#include <pubkey.h>
+#include <script/standard.h>
+#include <sync.h>
+#include <util/time.h>
+#include <validation.h>
+#include <validationinterface.h>
+
+#include <algorithm>
+#include <memory>
+#include <type_traits>
+
+#include <QAbstractTableModel>
+#include <QHBoxLayout>
+#include <QLineEdit>
+#include <QPushButton>
+#include <QScrollBar>
+#include <QVBoxLayout>
+#include <QWidget>
+
+namespace {
+
+bool IsDatacarrier(const CTxOut& txout)
+{
+    return (txout.scriptPubKey[0] == OP_RETURN && txout.nValue == 0);
+}
+
+size_t CountNonDatacarrierOutputs(const CTransactionRef& tx)
+{
+    size_t count = 0;
+    for (const auto& txout : tx->vout) {
+        if (IsDatacarrier(txout)) continue;
+        ++count;
+    }
+    return count;
+}
+
+const CTxOut* GetNonDatacarrierOutput(const CTransactionRef& tx, const size_t txout_index)
+{
+    size_t count = 0;
+    for (auto& txout : tx->vout) {
+        if (IsDatacarrier(txout)) continue;
+        if (count == txout_index) {
+            return &txout;
+        }
+        ++count;
+    }
+    return nullptr;
+}
+
+} // namespace
+
+const QString LogEntry::LogEntryTypeAbbreviation(const Type log_entry_type)
+{
+    switch (log_entry_type) {
+        case Type::Block:       return QObject::tr("Blk", "Tx Watch: Block type abbreviation");
+        case Type::Transaction: return QObject::tr("Txn", "Tx Watch: Transaction type abbreviation");
+    } // no default case, so the compiler can warn about missing cases
+
+    assert(false);
+}
+
+void LogEntry::init(const LogEntry& other)
+{
+    if (!other.m_data) {
+        m_data = nullptr;
+        return;
+    }
+    const meta_t n = *(meta_t*)other.m_data;
+    const int32_t relTimestamp = n & rel_ts_mask;
+    switch (n >> 30) {
+        case 1:  // CBlockIndex*
+            init(relTimestamp, other.getBlockIndex());
+            break;
+        case 2:  // CTransactionRef
+        {
+            CTransactionWeakref ptx(*other.get<CTransactionRef>());
+            init(relTimestamp, ptx, false);
+            break;
+        }
+        case 3:  // CTransactionWeakref
+            init(relTimestamp, *other.get<CTransactionWeakref>(), true);
+            break;
+        default: assert(false);
+    }
+}
+
+LogEntry::LogEntry(const LogEntry& other)
+{
+    init(other);
+}
+
+void LogEntry::init(int32_t relTimestamp, const CBlockIndex& blockindex)
+{
+    relTimestamp &= rel_ts_mask;
+    size_t alignment;
+    const size_t sz = data_sizeof<CBlockIndex*>(alignment);
+    m_data = (uint8_t*)::operator new(sz);
+    *((meta_t*)m_data) = relTimestamp | (1 << 30);
+    *((const CBlockIndex**)&m_data[alignment]) = &blockindex;
+}
+
+LogEntry::LogEntry(int32_t relTimestamp, const CBlockIndex& blockindex)
+{
+    init(relTimestamp, blockindex);
+}
+
+void LogEntry::init(int32_t relTimestamp, const CTransactionWeakref& tx, bool weak)
+{
+    relTimestamp &= rel_ts_mask;
+
+    // Allocate enough space for either, so we can convert between them
+    size_t alignment_shared, alignment_weak;
+    const size_t sz = std::max(data_sizeof<CTransactionRef>(alignment_shared), data_sizeof<CTransactionWeakref>(alignment_weak));
+    m_data = (uint8_t*)::operator new(sz);
+
+    uint32_t type;
+    if (weak) {
+        //std::allocator<std::weak_ptr<CTransaction>>::construct(m_data + alignment_weak, tx);
+        new (m_data + alignment_weak) CTransactionWeakref(tx);
+        type = 3;
+    } else {
+        new (m_data + alignment_shared) CTransactionRef(tx.lock());
+        type = 2;
+    }
+    *((meta_t*)m_data) = relTimestamp | (type << 30);
+}
+
+LogEntry::LogEntry(int32_t relTimestamp, const CTransactionWeakref& tx, bool weak)
+{
+    init(relTimestamp, tx, weak);
+}
+
+LogEntry::LogEntry(int32_t relTimestamp, const CTransactionRef& tx, bool weak)
+{
+    CTransactionWeakref ptx(tx);
+    init(relTimestamp, ptx, weak);
+}
+
+void LogEntry::clear()
+{
+    if (!m_data) {
+        return;
+    }
+    const meta_t n = *(meta_t*)m_data;
+    switch (n >> 30) {
+        case 1:  // CBlockIndex*
+            break;
+        case 2:  // CTransactionRef
+            get<CTransactionRef>()->~CTransactionRef();
+            break;
+        case 3:  // CTransactionWeakref
+            get<CTransactionWeakref>()->~CTransactionWeakref();
+            break;
+        default: assert(false);
+    }
+    delete m_data;
+}
+
+LogEntry::~LogEntry()
+{
+    clear();
+}
+
+LogEntry& LogEntry::operator=(const LogEntry& other)
+{
+    if (this != &other) {
+        clear();
+        init(other);
+    }
+    return *this;
+}
+
+LogEntry::operator bool() const
+{
+    return m_data;
+}
+
+int32_t LogEntry::getRelTimestamp() const
+{
+    const meta_t n = *(meta_t*)m_data;
+    return n & rel_ts_mask;
+}
+
+uint64_t LogEntry::getTimestamp(uint64_t now) const
+{
+    uint64_t ts = (now & ~rel_ts_mask64) | getRelTimestamp();
+    if (ts > now) {
+        ts -= (rel_ts_mask64 + 1);
+    }
+    return ts;
+}
+
+LogEntry::Type LogEntry::getType() const
+{
+    const meta_t n = *(meta_t*)m_data;
+    return (n >> 31) ? Type::Transaction : Type::Block;
+}
+
+const CBlockIndex& LogEntry::getBlockIndex() const
+{
+    return **(get<const CBlockIndex*>());
+}
+
+CTransactionRef LogEntry::getTransactionRef() const
+{
+    const meta_t n = *(meta_t*)m_data;
+    if ((n >> 30) & 1) {
+        return get<CTransactionWeakref>()->lock();
+    } else {
+        return *get<CTransactionRef>();
+    }
+}
+
+bool LogEntry::isWeak() const
+{
+    const meta_t n = *(meta_t*)m_data;
+    return ((n >> 30) == 3);
+}
+
+bool LogEntry::expired() const
+{
+    if (isWeak()) {
+        return get<CTransactionWeakref>()->expired();
+    }
+    return false;
+}
+
+void LogEntry::makeWeak()
+{
+    const meta_t n = *(meta_t*)m_data;
+    if ((n >> 30) != 2) {
+        return;
+    }
+    CTransactionRef * const ptx_old = get<CTransactionRef>();
+    CTransactionRef tx = *ptx_old;  // save a copy
+    ptx_old->~CTransactionRef();
+    CTransactionWeakref * const ptx_new = get<CTransactionWeakref>();
+    new (ptx_new) CTransactionWeakref(tx);
+    *((meta_t*)m_data) |= (3 << 30);
+}
+
+class NetWatchValidationInterface final : public CValidationInterface {
+private:
+    NetWatchLogModel& model;
+
+public:
+    explicit NetWatchValidationInterface(NetWatchLogModel& model_in) : model(model_in) {}
+    void ValidationInterfaceUnregistering() override;
+
+    void UpdatedBlockTip(const CBlockIndex *pindexNew, const CBlockIndex *pindexFork, bool fInitialDownload) override;
+    void TransactionAddedToMempool(const CTransactionRef&, uint64_t mempool_sequence) override;
+};
+
+void NetWatchValidationInterface::ValidationInterfaceUnregistering()
+{
+    model.OrphanedValidationInterface();
+}
+
+void NetWatchValidationInterface::UpdatedBlockTip(const CBlockIndex *pindexNew, const CBlockIndex *pindexFork, bool fInitialDownload)
+{
+    if (pindexNew != pindexFork) {
+        model.LogBlock(pindexNew);
+    }
+}
+
+void NetWatchValidationInterface::TransactionAddedToMempool(const CTransactionRef& tx, uint64_t mempool_sequence)
+{
+    model.LogTransaction(tx);
+}
+
+NetWatchLogModel::NetWatchLogModel(QWidget *parent) :
+    QAbstractTableModel(parent),
+    m_widget(parent),
+    m_validation_interface(new NetWatchValidationInterface(*this))
+{
+    RegisterValidationInterface(m_validation_interface);
+}
+
+NetWatchLogModel::~NetWatchLogModel()
+{
+    LOCK(cs);
+    if (m_validation_interface) {
+        UnregisterValidationInterface(m_validation_interface);
+        delete m_validation_interface;
+        m_validation_interface = nullptr;
+    }
+}
+
+void NetWatchLogModel::OrphanedValidationInterface()
+{
+    LOCK(cs);
+    delete m_validation_interface;
+    m_validation_interface = nullptr;
+}
+
+int NetWatchLogModel::rowCount(const QModelIndex& parent) const
+{
+    LOCK(cs);
+    return m_log.size() - m_logskip;
+}
+
+int NetWatchLogModel::columnCount(const QModelIndex& parent) const
+{
+    return HeaderCount;
+}
+
+QVariant NetWatchLogModel::data(const CBlockIndex& blockindex, int txout_index, const Header header) const
+{
+    switch (header) {
+        case Header::Type:
+            return LogEntry::LogEntryTypeAbbreviation(LogEntry::Type::Block);
+        case Header::Id:
+            return QString::fromStdString(blockindex.GetBlockHash().GetHex());
+        case Header::Address:
+        case Header::Value: {
+            if (blockindex.nTx == 0 || !(blockindex.nStatus & BLOCK_HAVE_DATA)) {
+                return QVariant();
+            }
+            CBlock block;
+            if (!node::ReadBlockFromDisk(block, &blockindex, Params().GetConsensus())) {
+                // Indicate error somehow?
+                return QVariant();
+            }
+            assert(block.vtx.size());
+            return data(block.vtx[0], txout_index, header);
+        }
+        case Header::Time:  // Not valid here
+            assert(false);
+    }
+    return QVariant();
+}
+
+QVariant NetWatchLogModel::data(const CTransactionRef& tx, int txout_index, const Header header) const
+{
+    switch (header) {
+        case Header::Type:
+            return LogEntry::LogEntryTypeAbbreviation(LogEntry::Type::Transaction);
+        case Header::Id:
+            return QString::fromStdString(tx->GetHash().GetHex());
+        case Header::Address: {
+            const CTxOut *ptxout = GetNonDatacarrierOutput(tx, txout_index);
+            if (!ptxout) {
+                // Only datacarriers
+                ptxout = &tx->vout[0];
+            }
+            CTxDestination txdest;
+            if (ptxout->scriptPubKey[0] == OP_RETURN && ptxout->nValue > 0) {
+                return tr("(Burn)", "Tx Watch: Provably burned value in transaction");
+            } else if (!ExtractDestination(ptxout->scriptPubKey, txdest)) {
+                return tr("(Unknown)", "Tx Watch: Unknown transaction output type");
+            }
+            return QString::fromStdString(EncodeDestination(txdest));
+        }
+        case Header::Value: {
+            const CTxOut *ptxout = GetNonDatacarrierOutput(tx, txout_index);
+            if (!ptxout) {
+                ptxout = &tx->vout[0];
+            }
+            if (m_client_model) {
+                return BitcoinUnits::format(m_client_model->getOptionsModel()->getDisplayUnit(), ptxout->nValue);
+            } else {
+                return qlonglong(ptxout->nValue);
+            }
+        }
+        case Header::Time:  // Not valid here
+            assert(false);
+    }
+    return QVariant();
+}
+
+const LogEntry& NetWatchLogModel::getLogEntryRow(int row) const
+{
+    AssertLockHeld(cs);
+    size_t pos = (m_logpos + row) % m_log.size();
+    return m_log[pos];
+}
+
+LogEntry& NetWatchLogModel::getLogEntryRow(int row)
+{
+    AssertLockHeld(cs);
+    size_t pos = (m_logpos + row) % m_log.size();
+    return m_log[pos];
+}
+
+bool NetWatchLogModel::isLogRowContinuation(int row) const
+{
+    AssertLockHeld(cs);
+    return !getLogEntryRow(row);
+}
+
+const LogEntry& NetWatchLogModel::findLogEntry(int row, int& out_entry_row) const
+{
+    AssertLockHeld(cs);
+    out_entry_row = 0;
+    while (row && isLogRowContinuation(row)) {
+        --row;
+        ++out_entry_row;
+    }
+    return getLogEntryRow(row);
+}
+
+QVariant NetWatchLogModel::data(const QModelIndex& index, int role) const
+{
+    const Header header = Header(index.column());
+    switch (role) {
+        case Qt::DisplayRole:
+            break;
+        case Qt::BackgroundRole: {
+            if (!data(index, Qt::DisplayRole).isValid()) {
+                return m_widget->palette().brush(QPalette::WindowText);
+            }
+            LogEntry::Type type;
+            {
+                int entry_row;
+                LOCK(cs);
+                const LogEntry& le = findLogEntry(index.row(), entry_row);
+                type = le.getType();
+            }
+            if (type == LogEntry::Type::Block) {
+                return m_widget->palette().brush(QPalette::AlternateBase);
+            }
+            return QVariant();
+        }
+        case Qt::ForegroundRole: {
+            if (index.column() < 3) {
+                bool iscont;
+                {
+                    LOCK(cs);
+                    iscont = isLogRowContinuation(index.row());
+                }
+                if (iscont) {
+                    QBrush brush = m_widget->palette().brush(QPalette::WindowText);
+                    QColor color = brush.color();
+                    color.setAlpha(color.alpha() / 2);
+                    brush.setColor(color);
+                    return brush;
+                }
+            }
+            return QVariant();
+        }
+        case Qt::TextAlignmentRole:
+            if (header == Header::Value) {
+                return QVariant(Qt::AlignRight | Qt::AlignVCenter);
+            }
+            return QVariant();
+        case Qt::FontRole:
+            if (header == Header::Id) {
+                return GUIUtil::fixedPitchFont();
+            }
+            return QVariant();
+        default:
+            return QVariant();
+    }
+    int entry_row;
+    LOCK(cs);
+    const LogEntry& le = findLogEntry(index.row(), entry_row);
+    if (header == Header::Time) {
+        return GUIUtil::dateTimeStr(le.getTimestamp(GetTime()));
+    }
+    const LogEntry::Type type = le.getType();
+    if (type == LogEntry::Type::Block) {
+        return data(le.getBlockIndex(), entry_row, header);
+    }
+    if (header == Header::Type) {
+        return LogEntry::LogEntryTypeAbbreviation(LogEntry::Type::Transaction);
+    }
+
+    if (le.expired()) {
+        return QVariant();
+    }
+    return data(le.getTransactionRef(), entry_row, header);
+}
+
+QVariant NetWatchLogModel::headerData(int section, Qt::Orientation orientation, int role) const
+{
+    if (orientation != Qt::Horizontal || role != Qt::DisplayRole) {
+        return QVariant();
+    }
+    switch (Header(section)) {
+        case Header::Time:     return tr("Time"   , "NetWatch: Time header");
+        case Header::Type:     return tr("Type"   , "NetWatch: Type header");
+        case Header::Id:       return tr("Id"     , "NetWatch: Block hash / Txid header");
+        case Header::Address:  return tr("Address", "NetWatch: Address header");
+        case Header::Value:
+            if (m_client_model) {
+                return BitcoinUnits::getAmountColumnTitle(m_client_model->getOptionsModel()->getDisplayUnit());
+            } else {
+                // Used only for sizing of the column
+                return BitcoinUnits::getAmountColumnTitle(BitcoinUnits::mBTC);
+            }
+    }
+    return QVariant();
+}
+
+NetWatchLogSearch::NetWatchLogSearch(const QString& query, int display_unit) :
+    m_query(query)
+{
+    const QRegExp reHex("^[\\da-f]+$", Qt::CaseInsensitive, QRegExp::RegExp2);
+    const QRegExp reType("^(T(xn?)?|B(lk?)?)$", Qt::CaseInsensitive, QRegExp::RegExp2);
+
+    m_check_type = m_query.length() < 4 && reType.exactMatch(m_query);
+    m_check_id = m_query.length() <= 64 && reHex.exactMatch(m_query);
+    m_check_addr = m_query.length() <= LONGEST_BECH32_ADDRESS;
+    CAmount val;
+    m_check_value = BitcoinUnits::parse(display_unit, m_query, &val) && val >= 0 && val <= BitcoinUnits::maxMoney();
+}
+
+bool NetWatchLogSearch::match(const NetWatchLogModel& model, int row) const
+{
+    if (model.data(model.index(row, int(NetWatchLogModel::Header::Time))).toString().contains(m_query)) {
+        return true;
+    } else if (m_check_type && model.data(model.index(row, int(NetWatchLogModel::Header::Type))).toString().contains(m_query, Qt::CaseInsensitive)) {
+        return true;
+    } else if (m_check_id && model.data(model.index(row, int(NetWatchLogModel::Header::Id))).toString().contains(m_query, Qt::CaseInsensitive)) {
+        return true;
+    } else if (m_check_addr && model.data(model.index(row, int(NetWatchLogModel::Header::Address))).toString().contains(m_query, Qt::CaseInsensitive)) {
+        return true;
+    } else if (m_check_value && model.data(model.index(row, int(NetWatchLogModel::Header::Value))).toString().contains(m_query)) {
+        return true;
+    }
+    return false;
+}
+
+void NetWatchLogModel::searchRows(const QString& query, QList<int>& results)
+{
+    const auto currentUnit = m_client_model->getOptionsModel()->getDisplayUnit();
+    NetWatchLogSearch *newsearch = new NetWatchLogSearch(query, currentUnit);
+    LOCK(cs);
+    delete m_current_search;
+    m_current_search = newsearch;
+
+    bool fAdding = false;
+    const size_t rows_used = rowCount();
+    for (size_t row = 0; row < rows_used; ++row) {
+        if (isLogRowContinuation(row) || newsearch->m_check_addr || newsearch->m_check_value) {
+            // Check for a match
+            fAdding = newsearch->match(*this, row);
+        }
+        if (fAdding) {
+            results.append(row);
+        }
+    }
+}
+
+void NetWatchLogModel::searchDisable() {
+    LOCK(cs);
+    delete m_current_search;
+    m_current_search = nullptr;
+}
+
+void NetWatchLogModel::log_append(const LogEntry& le, size_t& rows_used)
+{
+    AssertLockHeld(cs);
+    if (m_log.size() < logsizelimit) {
+        // Haven't filled up yet, so just push_back
+        // Ensure push_back will append the current circular buffer, not go in the middle somewhere
+        // NOTE: m_logpos and m_logskip can be non-zero here, when further outputs will be overwriting
+        assert(m_logpos == m_logskip);
+        m_log.push_back(le);
+    } else {
+        // Replace a deleted row
+        assert(m_logskip);
+        getLogEntryRow(rows_used) = le;
+        --m_logskip;
+    }
+    ++rows_used;
+    if (rows_used > max_nonweak_txouts) {
+        LogEntry& old_le = getLogEntryRow(rows_used - max_nonweak_txouts - 1);
+        if (old_le) {
+            old_le.makeWeak();
+        }
+    }
+}
+
+void NetWatchLogModel::LogAddEntry(const LogEntry& le, size_t vout_count)
+{
+    if (vout_count < 1) {
+        vout_count = 1;
+    }
+    const QModelIndex dummy;
+    LOCK(cs);
+    size_t rows_to_remove = 0;
+    if (vout_count >= max_vout_per_tx) {
+        vout_count = max_vout_per_tx;
+    }
+    size_t rows_used = rowCount();
+    if (rows_used > logsizelimit - vout_count) {
+        rows_to_remove = (rows_used + vout_count) - logsizelimit;
+    }
+    if (rows_to_remove) {
+        // Don't orphan continuation entries
+        while (isLogRowContinuation(rows_to_remove)) {
+            ++rows_to_remove;
+        }
+
+        beginRemoveRows(dummy, 0, rows_to_remove - 1);
+        m_logpos = (m_logpos + rows_to_remove) % m_log.size();
+        m_logskip += rows_to_remove;
+        endRemoveRows();
+
+        rows_used = rowCount();
+    }
+
+    const LogEntry cont_le;
+    const int first_new_row = rows_used, last_new_row = rows_used + vout_count - 1;
+    beginInsertRows(dummy, first_new_row, last_new_row);
+    log_append(le, rows_used);
+    for (size_t i = 1; i < vout_count; ++i) {
+        log_append(cont_le, rows_used);
+    }
+    endInsertRows();
+
+    if (m_current_search) {
+        QList<int> new_matches;
+        if (m_current_search->m_check_addr || m_current_search->m_check_value) {
+            for (int row = first_new_row; row <= last_new_row; ++row) {
+                if (m_current_search->match(*this, row)) {
+                    new_matches.append(row);
+                }
+            }
+        } else if (m_current_search->match(*this, first_new_row)) {
+            for (int row = first_new_row; row <= last_new_row; ++row) {
+                new_matches.append(row);
+            }
+        }
+        if (!new_matches.isEmpty()) {
+            Q_EMIT moreSearchResults(new_matches);
+        }
+    }
+}
+
+void NetWatchLogModel::LogBlock(const CBlockIndex* pblockindex)
+{
+    CBlock block;
+    if (!node::ReadBlockFromDisk(block, pblockindex, Params().GetConsensus())) {
+        // Indicate error somehow?
+        return;
+    }
+    assert(block.vtx.size());
+    const size_t vout_count = CountNonDatacarrierOutputs(block.vtx[0]);
+    LogAddEntry(LogEntry(GetTime(), *pblockindex), vout_count);
+}
+
+void NetWatchLogModel::LogTransaction(const CTransactionRef& tx)
+{
+    const size_t vout_count = CountNonDatacarrierOutputs(tx);
+    LogAddEntry(LogEntry(GetTime(), tx), vout_count);
+}
+
+void NetWatchLogModel::setClientModel(ClientModel *model)
+{
+    if (m_client_model) {
+        disconnect(m_client_model->getOptionsModel(), &OptionsModel::displayUnitChanged, this, &NetWatchLogModel::updateDisplayUnit);
+    }
+    m_client_model = model;
+    if (model) {
+        connect(model->getOptionsModel(), &OptionsModel::displayUnitChanged, this, &NetWatchLogModel::updateDisplayUnit);
+    }
+    updateDisplayUnit();
+}
+
+void NetWatchLogModel::updateDisplayUnit()
+{
+    Q_EMIT headerDataChanged(Qt::Horizontal, int(Header::Value), int(Header::Value));
+    Q_EMIT dataChanged(index(0, int(Header::Value)), index(rowCount() - 1, int(Header::Value)));
+}
+
+int NetWatchLogTestModel::rowCount(const QModelIndex& parent) const
+{
+    return 2;
+}
+
+QVariant NetWatchLogTestModel::data(const QModelIndex& index, int role) const
+{
+    const NetWatchLogModel::Header header = NetWatchLogModel::Header(index.column());
+    if (role == Qt::FontRole && header == Header::Id) {
+        return GUIUtil::fixedPitchFont();
+    } else if (role != Qt::DisplayRole) {
+        return QVariant();
+    }
+    switch (header) {
+        case Header::Time:
+            return QString{GUIUtil::dateTimeStr(GetTime()) + "4"};
+        case Header::Type:
+            return LogEntry::LogEntryTypeAbbreviation(LogEntry::Type(index.row()));
+        case Header::Id:
+            return QString(64, '0');
+        case Header::Address:
+            if (index.row()) {
+                return QString{"bc1" + QString(LONGEST_BECH32_ADDRESS-3, 'x')};
+            } else {
+                return QString(LONGEST_BASE58_ADDRESS, 'W');
+            }
+        case Header::Value:
+            return "20000000.00000000";
+    }
+    return QVariant();
+}
+
+GuiNetWatch::GuiNetWatch(const PlatformStyle *platformStyle, const NetworkStyle *networkStyle, QWidget *parent) :
+    QWidget(parent)
+{
+    QVBoxLayout * const layout = new QVBoxLayout(this);
+
+    m_search_editor = new QLineEdit(this);
+    m_search_editor->setPlaceholderText("Search");
+    layout->addWidget(m_search_editor);
+
+    m_log_view = new QTableView(this);
+    m_log_view->verticalHeader()->hide();
+    m_log_view->setSizePolicy(QSizePolicy(QSizePolicy::Ignored, QSizePolicy::Ignored));
+    m_log_view->setSelectionBehavior(QAbstractItemView::SelectRows);
+    m_log_view->setTabKeyNavigation(false);
+    m_log_view->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
+
+    {
+        NetWatchLogTestModel testmodel;
+        m_log_view->setModel(&testmodel);
+        m_log_view->resizeColumnsToContents();
+
+        log_model = new NetWatchLogModel(this);
+        m_log_view->setModel(log_model);
+    }
+    layout->addWidget(m_log_view);
+
+    setWindowTitle(tr(PACKAGE_NAME) + " - " + tr("Network Watch") + " " + networkStyle->getTitleAddText());
+    setMinimumSize(640, 480);
+    resize(layout->contentsMargins().left() + (m_log_view->frameWidth() * 2) + m_log_view->columnViewportPosition(NetWatchLogModel::HeaderCount-1) + m_log_view->columnWidth(NetWatchLogModel::HeaderCount-1) + m_log_view->verticalScrollBar()->size().width() + layout->contentsMargins().right(), 480);
+    setWindowIcon(networkStyle->getTrayAndWindowIcon());
+
+    connect(m_search_editor, &QLineEdit::textChanged, this, &GuiNetWatch::doSearch);
+
+    connect(log_model, &NetWatchLogModel::rowsRemoved, this, &GuiNetWatch::rowsRemoved);
+    connect(log_model, &NetWatchLogModel::rowsAboutToBeInserted, this, &GuiNetWatch::aboutToInsert);
+    connect(log_model, &NetWatchLogModel::rowsInserted, this, &GuiNetWatch::maybeScrollToBottom);
+    connect(log_model, &NetWatchLogModel::moreSearchResults, this, &GuiNetWatch::moreSearchResults);
+
+    connect(m_log_view->selectionModel(), &QItemSelectionModel::selectionChanged, this, &GuiNetWatch::maybeCancelSearch);
+
+    setLayout(layout);
+}
+
+void GuiNetWatch::setClientModel(ClientModel *model)
+{
+    log_model->setClientModel(model);
+}
+
+void GuiNetWatch::rowsRemoved(const QModelIndex& parent, int start, int end)
+{
+    if (m_log_view->verticalScrollBar()->value() >= m_log_view->verticalScrollBar()->maximum()) {
+        return;
+    }
+    // Maintain the current viewed entries in place
+    int scrollpos = m_log_view->verticalScrollBar()->value();
+    if (start < scrollpos) {
+        scrollpos -= std::max(0, 1 + end - start);
+        m_log_view->verticalScrollBar()->setValue(scrollpos);
+    }
+}
+
+void GuiNetWatch::aboutToInsert()
+{
+    m_adjust_scroll = (m_log_view->verticalScrollBar()->value() >= m_log_view->verticalScrollBar()->maximum());
+}
+
+void GuiNetWatch::maybeScrollToBottom()
+{
+    if (m_adjust_scroll) {
+        m_log_view->scrollToBottom();
+    }
+}
+
+void GuiNetWatch::doSearch(const QString& query)
+{
+    if (query.isEmpty()) {
+        log_model->searchDisable();
+        m_search_editor->setStyleSheet("");
+        return;
+    }
+    QList<int> results;
+    log_model->searchRows(query, results);
+    if (results.isEmpty()) {
+        m_search_editor->setStyleSheet(STYLE_INVALID);
+        return;
+    }
+    m_search_editor->setStyleSheet(STYLE_ACTIVE);
+    QItemSelectionModel& sel = *m_log_view->selectionModel();
+    m_dont_cancel_search = true;
+    sel.clear();
+    Q_FOREACH (int row, results) {
+        sel.select(log_model->index(row, 0), QItemSelectionModel::Rows | QItemSelectionModel::Select);
+    }
+    m_dont_cancel_search = false;
+    m_log_view->scrollTo(log_model->index(results.back(), int(NetWatchLogModel::Header::Id)));
+}
+
+void GuiNetWatch::moreSearchResults(const QList<int>& rows)
+{
+    m_search_editor->setStyleSheet(STYLE_ACTIVE);
+    QItemSelectionModel& sel = *m_log_view->selectionModel();
+    m_dont_cancel_search = true;
+    Q_FOREACH (int row, rows) {
+        sel.select(log_model->index(row, 0), QItemSelectionModel::Rows | QItemSelectionModel::Select);
+    }
+    m_dont_cancel_search = false;
+}
+
+void GuiNetWatch::maybeCancelSearch()
+{
+    if (m_dont_cancel_search) {
+        return;
+    }
+    m_search_editor->setStyleSheet("");
+    log_model->searchDisable();
+}
diff --git a/src/qt/netwatch.h b/src/qt/netwatch.h
new file mode 100644
index 00000000000..556ef019314
--- /dev/null
+++ b/src/qt/netwatch.h
@@ -0,0 +1,230 @@
+// Copyright (c) 2017-2021 The Bitcoin Core developers
+// Copyright (c) 2011-2013 David Krauss (std::align substitute from c-plus)
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_QT_NETWATCH_H
+#define BITCOIN_QT_NETWATCH_H
+
+#include <primitives/transaction.h>
+#include <sync.h>
+#include <validationinterface.h>
+
+#include <QAbstractTableModel>
+#include <QWidget>
+
+QT_BEGIN_NAMESPACE
+class QLineEdit;
+class QTableView;
+QT_END_NAMESPACE
+
+class CBlock;
+class CBlockIndex;
+class ClientModel;
+class LogEntry;
+class NetworkStyle;
+class PlatformStyle;
+
+static constexpr int LONGEST_BASE58_ADDRESS{35};
+static constexpr int LONGEST_BECH32_ADDRESS{62};  // NOTE: Up to 74 in theory, but 62 in practice
+
+class LogEntry {
+private:
+    /**
+     * m_data is a uint32_t (meta_t) with the top two bits used for:
+     *   1: CBlockIndex*
+     *   2: CTransactionRef
+     *   3: weak_ptr<const CTransaction>
+     * The subsequent 30 bits are the timestamp, assumed to be most recent to the current time.
+     * Following this, and any padding necessary for alignment, the object itself is stored
+     */
+    uint8_t *m_data{nullptr};
+
+    typedef uint32_t meta_t;
+    typedef std::weak_ptr<const CTransaction> CTransactionWeakref;
+    static constexpr uint32_t rel_ts_mask{0x3fffffff};
+    static constexpr uint64_t rel_ts_mask64{rel_ts_mask};
+
+    template<typename T> static size_t data_sizeof(size_t& offset) {
+        void *p = (void *)intptr_t(sizeof(meta_t));
+        size_t dummy_bufsize = sizeof(T) * 2;
+        p = align(std::alignment_of<T>::value, sizeof(T), p, dummy_bufsize);
+        assert(p);
+        offset = size_t(p);
+        return offset + sizeof(T);
+    }
+
+    // std::align (missing in at least GCC 4.9) substitute from c-plus
+    static inline void *align(std::size_t alignment, std::size_t size, void *&ptr, std::size_t &space) {
+        auto pn = reinterpret_cast<std::uintptr_t>(ptr);
+        auto aligned = (pn + alignment - 1) & -alignment;
+        auto new_space = space - (aligned - pn);
+        if (new_space < size) {
+            return nullptr;
+        }
+        space = new_space;
+        return ptr = reinterpret_cast<void *>(aligned);
+    }
+
+    void init(const LogEntry&);
+    void init(int32_t relTimestamp, const CBlockIndex&);
+    void init(int32_t relTimestamp, const CTransactionWeakref&, bool weak);
+    void clear();
+
+public:
+    enum class Type {
+        Block,
+        Transaction,
+    };
+    static const QString LogEntryTypeAbbreviation(Type);
+
+    LogEntry(const LogEntry&);
+    LogEntry() { }
+    explicit LogEntry(int32_t relTimestamp, const CBlockIndex&);
+    explicit LogEntry(int32_t relTimestamp, const CTransactionWeakref&, bool weak = true);
+    explicit LogEntry(int32_t relTimestamp, const CTransactionRef&, bool weak = false);
+    ~LogEntry();
+
+    LogEntry& operator=(const LogEntry& other);
+
+    explicit operator bool() const;
+    int32_t getRelTimestamp() const;
+    uint64_t getTimestamp(uint64_t now) const;
+    Type getType() const;
+
+    template <typename T> T* get() const {
+        void *p = m_data + sizeof(meta_t);
+        size_t dummy_bufsize = sizeof(T) * 2;
+        p = align(std::alignment_of<T>::value, sizeof(T), p, dummy_bufsize);
+        assert(p);
+        return (T*)p;
+    }
+
+    const CBlockIndex& getBlockIndex() const;
+    CTransactionRef getTransactionRef() const;
+    bool isWeak() const;
+    bool expired() const;
+    void makeWeak();
+};
+
+class NetWatchLogModel;
+
+class NetWatchLogSearch {
+public:
+    QString m_query;
+
+    bool m_check_type;
+    bool m_check_id;
+    bool m_check_addr;
+    bool m_check_value;
+
+    NetWatchLogSearch(const QString& query, int display_unit);
+    bool match(const NetWatchLogModel& model, int row) const;
+};
+
+class NetWatchValidationInterface;
+
+class NetWatchLogModel : public QAbstractTableModel
+{
+    Q_OBJECT
+
+private:
+    QWidget * const m_widget;
+    ClientModel *m_client_model{nullptr};
+
+    NetWatchValidationInterface *m_validation_interface;
+
+    mutable RecursiveMutex cs;
+    std::vector<LogEntry> m_log GUARDED_BY(cs);
+    static constexpr size_t logsizelimit{0x400};
+    size_t m_logpos GUARDED_BY(cs) {0};
+    size_t m_logskip GUARDED_BY(cs) {0};
+
+    static constexpr size_t max_nonweak_txouts{0x200};
+    static constexpr size_t max_vout_per_tx{0x100};
+
+    NetWatchLogSearch *m_current_search GUARDED_BY(cs) {nullptr};
+
+    const LogEntry& getLogEntryRow(int row) const EXCLUSIVE_LOCKS_REQUIRED(cs);
+    LogEntry& getLogEntryRow(int row) EXCLUSIVE_LOCKS_REQUIRED(cs);
+    void log_append(const LogEntry&, size_t& rows_used) EXCLUSIVE_LOCKS_REQUIRED(cs);
+
+public:
+    static constexpr int HeaderCount{5};
+    enum class Header {
+        Time,
+        Type,
+        Id,
+        Address,
+        Value,
+    };
+
+    explicit NetWatchLogModel(QWidget *parent);
+    ~NetWatchLogModel();
+
+    void setClientModel(ClientModel *model);
+    void OrphanedValidationInterface();
+
+    bool isLogRowContinuation(int row) const EXCLUSIVE_LOCKS_REQUIRED(cs);
+    const LogEntry& findLogEntry(int row, int& out_entry_row) const EXCLUSIVE_LOCKS_REQUIRED(cs);
+
+    int rowCount(const QModelIndex& parent = QModelIndex()) const override;
+    int columnCount(const QModelIndex& parent) const override;
+    QVariant data(const CBlockIndex&, int txout_index, const Header) const;
+    QVariant data(const CTransactionRef&, int txout_index, const Header) const;
+    QVariant data(const QModelIndex&, int role = Qt::DisplayRole) const override;
+    QVariant headerData(int section, Qt::Orientation, int role = Qt::DisplayRole) const override;
+
+    void searchRows(const QString& query, QList<int>& results);
+    void searchDisable();
+
+    void LogAddEntry(const LogEntry& le, size_t vout_count);
+    void LogBlock(const CBlockIndex*);
+    void LogTransaction(const CTransactionRef&);
+
+Q_SIGNALS:
+    void moreSearchResults(const QList<int>& rows);
+
+public Q_SLOTS:
+    void updateDisplayUnit();
+};
+
+class NetWatchLogTestModel : public NetWatchLogModel
+{
+    Q_OBJECT
+
+public:
+    NetWatchLogTestModel() : NetWatchLogModel(nullptr) { }
+
+    int rowCount(const QModelIndex& parent) const override;
+    QVariant data(const QModelIndex&, int role = Qt::DisplayRole) const override;
+};
+
+class GuiNetWatch: public QWidget
+{
+    Q_OBJECT
+
+private:
+    bool m_adjust_scroll;
+
+public:
+    GuiNetWatch(const PlatformStyle *, const NetworkStyle *, QWidget * parent = nullptr);
+
+    void setClientModel(ClientModel *model);
+
+    NetWatchLogModel *log_model;
+    bool m_dont_cancel_search{false};
+
+    QLineEdit *m_search_editor;
+    QTableView *m_log_view;
+
+public Q_SLOTS:
+    void rowsRemoved(const QModelIndex& parent, int start, int end);
+    void aboutToInsert();
+    void maybeScrollToBottom();
+    void doSearch(const QString& query);
+    void moreSearchResults(const QList<int>& rows);
+    void maybeCancelSearch();
+};
+
+#endif // BITCOIN_QT_NETWATCH_H
diff --git a/src/qt/rpcconsole.h b/src/qt/rpcconsole.h
index 528e2bef7d5..dbf15232b3a 100644
--- a/src/qt/rpcconsole.h
+++ b/src/qt/rpcconsole.h
@@ -16,6 +16,7 @@
 #include <QWidget>
 
 class ClientModel;
+class GuiNetWatch;
 class PlatformStyle;
 class RPCTimerInterface;
 class WalletModel;
@@ -155,6 +156,7 @@ public Q_SLOTS:
     interfaces::Node& m_node;
     Ui::RPCConsole* const ui;
     ClientModel *clientModel = nullptr;
+    GuiNetWatch *netwatch = nullptr;
     QStringList history;
     int historyPtr = 0;
     QString cmdBeforeBrowsing;
diff --git a/src/validationinterface.cpp b/src/validationinterface.cpp
index 1e07ff23ae8..83fc6e62369 100644
--- a/src/validationinterface.cpp
+++ b/src/validationinterface.cpp
@@ -139,6 +139,8 @@ void UnregisterSharedValidationInterface(std::shared_ptr<CValidationInterface> c
 
 void UnregisterValidationInterface(CValidationInterface* callbacks)
 {
+    callbacks->ValidationInterfaceUnregistering();
+
     if (g_signals.m_internals) {
         g_signals.m_internals->Unregister(callbacks);
     }
@@ -149,6 +151,9 @@ void UnregisterAllValidationInterfaces()
     if (!g_signals.m_internals) {
         return;
     }
+
+    g_signals.m_internals->Iterate([&](CValidationInterface& callbacks) { callbacks.ValidationInterfaceUnregistering(); });
+
     g_signals.m_internals->Clear();
 }
 
diff --git a/src/validationinterface.h b/src/validationinterface.h
index 7c3ce00fbcc..0f958f4fb02 100644
--- a/src/validationinterface.h
+++ b/src/validationinterface.h
@@ -173,6 +173,13 @@ class CValidationInterface {
      * Notifies listeners that a block which builds directly on our current tip
      * has been received and connected to the headers tree, though not validated yet */
     virtual void NewPoWValidBlock(const CBlockIndex *pindex, const std::shared_ptr<const CBlock>& block) {};
+    /**
+     * Notifies the validation interface that it is being unregistered
+     */
+    virtual void ValidationInterfaceUnregistering() {};
+
+    friend void UnregisterValidationInterface(CValidationInterface*);
+    friend void UnregisterAllValidationInterfaces();
     friend class CMainSignals;
 };