diff --git a/tox.ini b/tox.ini
index 8d875b8..b7a754e 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,4 +1,6 @@
 [flake8]
 max-line-length = 120
 exclude = .git,build,dist,__pycache__,.eggs,*.egg-info,venv
-ignore = E203
+# E203 is for expressions inside a slice, and it conflicts with Black.
+# W503 is "line break before binary operator", and fixing that triggers W504.
+ignore = E203,W503
diff --git a/uit/async_client.py b/uit/async_client.py
index da74389..3328009 100644
--- a/uit/async_client.py
+++ b/uit/async_client.py
@@ -8,7 +8,7 @@
 import time
 import uuid
 from pathlib import PurePosixPath, Path
-from urllib.parse import urljoin, urlencode  # noqa: F401
+from urllib.parse import urljoin
 
 import param
 import aiohttp
@@ -27,6 +27,7 @@
     encode_pure_posix_path,
     FG_CYAN,
     ALL_OFF,
+    _auth_code,
 )
 from .util import robust, AsyncHpcEnv
 from .pbs_script import PbsScript
@@ -171,7 +172,6 @@ async def get_token(self, auth_code=None):
 
         url = urljoin(UIT_API_URL, "token")
 
-        global _auth_code
         self._auth_code = auth_code or _auth_code
 
         # check for auth_code
@@ -396,6 +396,92 @@ async def get_file(self, remote_path, local_path=None, timeout=30):
 
         return local_path
 
+    async def _get_dir_stats(self, local_dir, remote_dir, get_dir=False):
+        local_dir = Path(local_dir)
+        remote_dir = PurePosixPath(remote_dir)
+        # get remote dir stats
+        try:
+            remote_dir_stats = await self.call(f"find {remote_dir.as_posix()} -type f -printf '%Ts %s %P\n'")
+            # Remote mtime is always an integer, so this ignores decimals for local and remote mtime
+            # That avoids re-transferring files with microsecond timestamp differences
+            remote_files = {
+                stats[-1]: {"mtime": int(stats[0]), "size": int(stats[1])}
+                for stats in [line.split() for line in remote_dir_stats.splitlines()]
+            }
+        except Exception as e:
+            logger.debug(e)
+            remote_files = {}
+            if get_dir:
+                return {}, {}, {}, {}
+
+        # get local dir stats
+        if get_dir:
+            local_dir.mkdir(parents=True, exist_ok=True)
+        local_files = {p.relative_to(local_dir).as_posix(): p.stat() for p in local_dir.glob("**/*") if p.is_file()}
+
+        # compare
+        not_local = {}
+        not_remote = local_files
+        for name, remote_stats in remote_files.items():
+            # get local stats for same file name if it exists
+            local_stats = local_files.get(name)
+
+            # compare file size and mtime
+            if not (
+                local_stats
+                and local_stats.st_size == remote_stats["size"]
+                and local_stats.st_mtime == remote_stats["mtime"]
+            ):
+                not_local[name] = remote_stats
+            else:
+                not_remote.pop(name)
+
+        return remote_files, local_files, not_remote, not_local
+
+    @_ensure_connected
+    @robust()
+    async def put_dir(self, local_dir, remote_dir):
+        _, local_files, not_remote, __ = await self._get_dir_stats(local_dir, remote_dir)
+
+        async def put_file_with_stats(file_name):
+            remote_file_path = PurePosixPath(remote_dir) / file_name
+            local_file_path = Path(local_dir) / file_name
+            await self.put_file(local_file_path, remote_file_path)
+            mtime = int(local_files[file_name].st_mtime)
+            await self.call(f"touch -d @{mtime} {remote_file_path}")
+
+        remote_dirs_to_create = set()
+        for file_name in not_remote:
+            remote_dirs_to_create.add(Path(file_name).parent)
+
+        if remote_dirs_to_create:
+            logger.info(f"Creating {len(remote_dirs_to_create)} directories before file uploads")
+            for this_remote_dir in remote_dirs_to_create:
+                await self.call(f"mkdir -p {PurePosixPath(remote_dir) / this_remote_dir}")
+
+        # transfer files that didn't match those on the hpc
+        logger.info(f"Uploading {len(not_remote)} files")
+        for file_name in not_remote:
+            await put_file_with_stats(file_name)
+
+    @_ensure_connected
+    @robust()
+    async def get_dir(self, remote_dir, local_dir):
+        remote_files, _, __, not_local = await self._get_dir_stats(local_dir, remote_dir, get_dir=True)
+
+        async def get_file_with_stats(file_name):
+            remote_file_path = PurePosixPath(remote_dir) / file_name
+            local_file_path = Path(local_dir) / file_name
+            local_file_path.parent.mkdir(parents=True, exist_ok=True)
+            await self.get_file(remote_file_path, local_file_path)
+            mtime = remote_files[file_name]["mtime"]
+            os.utime(local_file_path, (mtime, mtime))
+
+        # transfer files that didn't match those on the hpc
+        logger.info(f"Downloading {len(not_local)} files")
+        for file_name in not_local:
+            await get_file_with_stats(file_name)
+
     @_ensure_connected
     @robust()
     async def list_dir(self, path=None, parse=True, as_df=False, timeout=30):
diff --git a/uit/uit.py b/uit/uit.py
index 41f9e8d..2fcac0b 100644
--- a/uit/uit.py
+++ b/uit/uit.py
@@ -369,7 +369,6 @@ def get_token(self, auth_code=None):
 
         url = urljoin(UIT_API_URL, "token")
 
-        global _auth_code
         self._auth_code = auth_code or _auth_code
 
         # check for auth_code