diff --git a/api-server/src/handlers.rs b/api-server/src/handlers.rs
index b1f1c36..6769491 100644
--- a/api-server/src/handlers.rs
+++ b/api-server/src/handlers.rs
@@ -1,6 +1,7 @@
 use axum::{extract::Path, http::StatusCode, Json};
 use tracing::instrument;
 use crate::schemas::*;
+use crate::webhook;
 
 /// Timestamp a new IP commitment. Returns the assigned IP ID.
 #[utoipa::path(
@@ -146,6 +147,8 @@ pub async fn initiate_swap(Json(body): Json<InitiateSwapRequest>) -> Result<Json
 #[instrument(skip(body))]
 pub async fn accept_swap(Path(swap_id): Path<u64>, Json(body): Json<AcceptSwapRequest>) -> Result<StatusCode, (StatusCode, Json<ErrorResponse>)> {
     // TODO: Call Soroban RPC to invoke atomic_swap.accept_swap
+    // Trigger webhook on status change (Pending -> Accepted)
+    webhook::trigger_swap_status_changed(swap_id, Some("Pending".to_string()), "Accepted".to_string());
     Err((
         StatusCode::NOT_FOUND,
         Json(ErrorResponse {
@@ -170,6 +173,8 @@ pub async fn accept_swap(Path(swap_id): Path<u64>, Json(body): Json<AcceptSwapRe
 #[instrument(skip(body))]
 pub async fn reveal_key(Path(swap_id): Path<u64>, Json(body): Json<RevealKeyRequest>) -> Result<StatusCode, (StatusCode, Json<ErrorResponse>)> {
     // TODO: Call Soroban RPC to invoke atomic_swap.reveal_key
+    // Trigger webhook on status change (Accepted -> Completed)
+    webhook::trigger_swap_status_changed(swap_id, Some("Accepted".to_string()), "Completed".to_string());
     Err((
         StatusCode::NOT_FOUND,
         Json(ErrorResponse {
@@ -194,6 +199,8 @@ pub async fn reveal_key(Path(swap_id): Path<u64>, Json(body): Json<RevealKeyRequ
 #[instrument(skip(body))]
 pub async fn cancel_swap(Path(swap_id): Path<u64>, Json(body): Json<CancelSwapRequest>) -> Result<StatusCode, (StatusCode, Json<ErrorResponse>)> {
     // TODO: Call Soroban RPC to invoke atomic_swap.cancel_swap
+    // Trigger webhook on status change (Pending -> Cancelled)
+    webhook::trigger_swap_status_changed(swap_id, Some("Pending".to_string()), "Cancelled".to_string());
     Err((
         StatusCode::NOT_FOUND,
         Json(ErrorResponse {
@@ -218,6 +225,8 @@ pub async fn cancel_swap(Path(swap_id): Path<u64>, Json(body): Json<CancelSwapRe
 #[instrument(skip(body))]
 pub async fn cancel_expired_swap(Path(swap_id): Path<u64>, Json(body): Json<CancelExpiredSwapRequest>) -> Result<StatusCode, (StatusCode, Json<ErrorResponse>)> {
     // TODO: Call Soroban RPC to invoke atomic_swap.cancel_expired_swap
+    // Trigger webhook on status change (Accepted -> Cancelled)
+    webhook::trigger_swap_status_changed(swap_id, Some("Accepted".to_string()), "Cancelled".to_string());
     Err((
         StatusCode::NOT_FOUND,
         Json(ErrorResponse {
@@ -247,3 +256,65 @@ pub async fn get_swap(Path(swap_id): Path<u64>) -> Result<Json<SwapRecord>, (Sta
         }),
     ))
 }
+
+/// Register a webhook URL to receive swap event notifications.
+#[utoipa::path(
+    post,
+    path = "/webhooks",
+    tag = "Webhooks",
+    request_body = RegisterWebhookRequest,
+    responses(
+        (status = 200, description = "Webhook registered", body = WebhookResponse),
+        (status = 400, description = "Invalid request", body = ErrorResponse),
+    )
+)]
+pub async fn register_webhook(Json(body): Json<RegisterWebhookRequest>) -> Result<Json<WebhookResponse>, (StatusCode, Json<ErrorResponse>)> {
+    if body.url.is_empty() || body.events.is_empty() {
+        return Err((
+            StatusCode::BAD_REQUEST,
+            Json(ErrorResponse {
+                error: "URL and events are required".to_string(),
+            }),
+        ));
+    }
+
+    let config = webhook::register(body.url, body.events);
+
+    Ok(Json(WebhookResponse {
+        id: config.id.to_string(),
+        url: config.url,
+        events: config.events,
+        created_at: config.created_at,
+    }))
+}
+
+/// Unregister a webhook by ID.
+#[utoipa::path(
+    delete,
+    path = "/webhooks/{id}",
+    tag = "Webhooks",
+    params(("id" = String, Path, description = "Webhook UUID")),
+    responses(
+        (status = 200, description = "Webhook unregistered"),
+        (status = 404, description = "Webhook not found", body = ErrorResponse),
+    )
+)]
+pub async fn unregister_webhook(Path(id): Path<String>) -> Result<StatusCode, (StatusCode, Json<ErrorResponse>)> {
+    let uuid = uuid::Uuid::parse_str(&id).map_err(|_| (
+        StatusCode::BAD_REQUEST,
+        Json(ErrorResponse {
+            error: "Invalid webhook ID format".to_string(),
+        }),
+    ))?;
+
+    if webhook::unregister(uuid) {
+        Ok(StatusCode::OK)
+    } else {
+        Err((
+            StatusCode::NOT_FOUND,
+            Json(ErrorResponse {
+                error: format!("Webhook {} not found", id),
+            }),
+        ))
+    }
+}
diff --git a/api-server/src/main.rs b/api-server/src/main.rs
index 5d5437a..7a06ee9 100644
--- a/api-server/src/main.rs
+++ b/api-server/src/main.rs
@@ -6,6 +6,7 @@ use utoipa_swagger_ui::SwaggerUi;
 mod handlers;
 mod metrics;
 mod schemas;
+mod webhook;
 
 #[derive(OpenApi)]
 #[openapi(
@@ -26,6 +27,8 @@ mod schemas;
         handlers::cancel_swap,
         handlers::cancel_expired_swap,
         handlers::get_swap,
+        handlers::register_webhook,
+        handlers::unregister_webhook,
     ),
     components(schemas(
         schemas::CommitIpRequest,
@@ -42,10 +45,13 @@ mod schemas;
         schemas::SwapRecord,
         schemas::SwapStatus,
         schemas::ErrorResponse,
+        schemas::RegisterWebhookRequest,
+        schemas::WebhookResponse,
     )),
     tags(
         (name = "IP Registry", description = "Commit and query intellectual property records"),
         (name = "Atomic Swap", description = "Trustless patent sale via atomic swap"),
+        (name = "Webhooks", description = "Real-time event notifications"),
     )
 )]
 pub struct ApiDoc;
diff --git a/api-server/src/schemas.rs b/api-server/src/schemas.rs
index b348e62..03a7557 100644
--- a/api-server/src/schemas.rs
+++ b/api-server/src/schemas.rs
@@ -107,3 +107,17 @@ pub struct CancelExpiredSwapRequest {
 pub struct ErrorResponse {
     pub error: String,
 }
+
+#[derive(Debug, Serialize, Deserialize, ToSchema)]
+pub struct RegisterWebhookRequest {
+    pub url: String,
+    pub events: Vec<String>,
+}
+
+#[derive(Debug, Serialize, Deserialize, ToSchema)]
+pub struct WebhookResponse {
+    pub id: String,
+    pub url: String,
+    pub events: Vec<String>,
+    pub created_at: u64,
+}
diff --git a/api-server/src/webhook.rs b/api-server/src/webhook.rs
new file mode 100644
index 0000000..a9999b7
--- /dev/null
+++ b/api-server/src/webhook.rs
@@ -0,0 +1,155 @@
+use std::time::Duration;
+use axum::http::StatusCode;
+use dashmap::DashMap;
+use once_cell::sync::Lazy;
+use reqwest::Client;
+use serde::{Deserialize, Serialize};
+use serde_json::json;
+use tracing::{error, info, warn};
+use uuid::Uuid;
+
+/// Configuration for a registered webhook.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct WebhookConfig {
+    pub id: Uuid,
+    pub url: String,
+    pub events: Vec<String>, // e.g., ["swap.status_changed"]
+    pub created_at: u64,
+}
+
+/// Webhook delivery payload.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct WebhookPayload {
+    pub event: String,
+    pub swap_id: u64,
+    pub old_status: Option<String>,
+    pub new_status: String,
+    pub timestamp: u64,
+}
+
+/// In-memory webhook registry.
+static REGISTRY: Lazy<DashMap<Uuid, WebhookConfig>> = Lazy::new(DashMap::new);
+
+/// HTTP client for webhook delivery.
+static CLIENT: Lazy<Client> = Lazy::new(|| {
+    Client::builder()
+        .timeout(Duration::from_secs(10))
+        .build()
+        .expect("Failed to build reqwest client")
+});
+
+/// Register a new webhook.
+pub fn register(url: String, events: Vec<String>) -> WebhookConfig {
+    let config = WebhookConfig {
+        id: Uuid::new_v4(),
+        url,
+        events,
+        created_at: std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .unwrap()
+            .as_secs(),
+    };
+    REGISTRY.insert(config.id, config.clone());
+    info!(webhook_id = %config.id, url = %config.url, "Webhook registered");
+    config
+}
+
+/// Unregister a webhook by ID.
+pub fn unregister(id: Uuid) -> bool {
+    if REGISTRY.remove(&id).is_some() {
+        info!(webhook_id = %id, "Webhook unregistered");
+        true
+    } else {
+        false
+    }
+}
+
+/// List all registered webhooks.
+pub fn list_all() -> Vec<WebhookConfig> {
+    REGISTRY.iter().map(|entry| entry.clone()).collect()
+}
+
+/// Trigger webhook delivery for a swap status change.
+pub fn trigger_swap_status_changed(swap_id: u64, old_status: Option<String>, new_status: String) {
+    let payload = WebhookPayload {
+        event: "swap.status_changed".to_string(),
+        swap_id,
+        old_status,
+        new_status,
+        timestamp: std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .unwrap()
+            .as_secs(),
+    };
+
+    for entry in REGISTRY.iter() {
+        let config = entry.value();
+        if config.events.contains(&"swap.status_changed".to_string()) || config.events.contains(&"*".to_string()) {
+            let config = config.clone();
+            let payload = payload.clone();
+            tokio::spawn(async move {
+                deliver_with_retry(&config, &payload).await;
+            });
+        }
+    }
+}
+
+/// Deliver a webhook payload with exponential backoff retry.
+async fn deliver_with_retry(config: &WebhookConfig, payload: &WebhookPayload) {
+    let mut delay = Duration::from_secs(1);
+    let max_retries = 3;
+
+    for attempt in 1..=max_retries {
+        match deliver(&config.url, payload).await {
+            Ok(status) if status.is_success() => {
+                info!(
+                    webhook_id = %config.id,
+                    url = %config.url,
+                    attempt,
+                    "Webhook delivered successfully"
+                );
+                return;
+            }
+            Ok(status) => {
+                warn!(
+                    webhook_id = %config.id,
+                    url = %config.url,
+                    attempt,
+                    status = status.as_u16(),
+                    "Webhook delivery returned non-success status"
+                );
+            }
+            Err(e) => {
+                warn!(
+                    webhook_id = %config.id,
+                    url = %config.url,
+                    attempt,
+                    error = %e,
+                    "Webhook delivery failed"
+                );
+            }
+        }
+
+        if attempt < max_retries {
+            tokio::time::sleep(delay).await;
+            delay *= 2; // exponential backoff: 1s, 2s, 4s
+        }
+    }
+
+    error!(
+        webhook_id = %config.id,
+        url = %config.url,
+        "Webhook delivery exhausted all retries"
+    );
+}
+
+/// Single delivery attempt.
+async fn deliver(url: &str, payload: &WebhookPayload) -> Result<StatusCode, reqwest::Error> {
+    let response = CLIENT
+        .post(url)
+        .json(&json!(payload))
+        .send()
+        .await?;
+    Ok(response.status())
+}
+