diff --git a/nostr-sdk/CHANGELOG.md b/nostr-sdk/CHANGELOG.md
index dc65dd5e0..1c9485f5a 100644
--- a/nostr-sdk/CHANGELOG.md
+++ b/nostr-sdk/CHANGELOG.md
@@ -27,6 +27,12 @@
 
 -->
 
+## Unreleased
+
+### Changed
+
+- local_relay: default connection limit set to 512 (https://github.com/nostrdevkit/nostr/pull/1462)
+
 ## v0.45.2 - 2026/08/19
 
 ### Fixed
diff --git a/nostr-sdk/src/local_relay/builder.rs b/nostr-sdk/src/local_relay/builder.rs
index 5a4905cb7..cee5d91df 100644
--- a/nostr-sdk/src/local_relay/builder.rs
+++ b/nostr-sdk/src/local_relay/builder.rs
@@ -17,6 +17,7 @@ use nostr_database::prelude::*;
 use super::local::LocalRelay;
 
 pub(super) const DEFAULT_MAX_PENDING_HANDSHAKES: usize = 128;
+pub(super) const DEFAULT_CONNECTIONS_LIMIT: usize = 512;
 pub(super) const DEFAULT_MAX_FILTERS_PER_REQ: usize = 20;
 pub(super) const DEFAULT_MAX_EVENT_SIZE: usize = 64 * 1024;
 pub(super) const DEFAULT_MAX_QUERY_RESULTS: usize = 500;
@@ -285,7 +286,7 @@ pub struct LocalRelayBuilder {
     /// NIP42 options
     pub(crate) nip42: Option<LocalRelayBuilderNip42>,
     /// Max connections allowed
-    pub(crate) max_connections: Option<usize>,
+    pub(crate) max_connections: usize,
     /// Max WebSocket message size
     pub(crate) max_websocket_message_size: usize,
     /// Max event size in bytes
@@ -345,7 +346,7 @@ impl Default for LocalRelayBuilder {
             auth_events_per_minute: DEFAULT_AUTH_EVENTS_PER_MINUTE,
             messages_per_minute: DEFAULT_MESSAGES_PER_MINUTE,
             nip42: None,
-            max_connections: None,
+            max_connections: DEFAULT_CONNECTIONS_LIMIT,
             max_websocket_message_size: DEFAULT_MAX_WEBSOCKET_MESSAGE_SIZE,
             max_event_size: DEFAULT_MAX_EVENT_SIZE,
             websocket_handshake_timeout: DEFAULT_WEBSOCKET_HANDSHAKE_TIMEOUT,
@@ -448,10 +449,10 @@ impl LocalRelayBuilder {
         self
     }
 
-    /// Set number of max connections allowed. By default, connections are unlimited.
+    /// Limits the maximum number of concurrent connections. Defaults to 512.
     #[inline]
     pub fn max_connections(mut self, max: usize) -> Self {
-        self.max_connections = Some(max);
+        self.max_connections = max.min(tokio::sync::Semaphore::MAX_PERMITS);
         self
     }
 
diff --git a/nostr-sdk/src/local_relay/local/inner.rs b/nostr-sdk/src/local_relay/local/inner.rs
index b2f7544b5..1ac2a49f0 100644
--- a/nostr-sdk/src/local_relay/local/inner.rs
+++ b/nostr-sdk/src/local_relay/local/inner.rs
@@ -113,9 +113,7 @@ impl InnerLocalRelay {
             auth_events_per_minute: builder.auth_events_per_minute,
             messages_per_minute: builder.messages_per_minute,
             pending_handshakes_limit: Arc::new(Semaphore::new(DEFAULT_MAX_PENDING_HANDSHAKES)),
-            connections_limit: Arc::new(Semaphore::new(
-                builder.max_connections.unwrap_or(Semaphore::MAX_PERMITS),
-            )),
+            connections_limit: Arc::new(Semaphore::new(builder.max_connections)),
             max_websocket_message_size: builder.max_websocket_message_size,
             max_event_size: builder.max_event_size,
             websocket_handshake_timeout: builder.websocket_handshake_timeout,
@@ -1655,6 +1653,7 @@ where
 #[cfg(test)]
 mod tests {
     use super::*;
+    use crate::local_relay::DEFAULT_CONNECTIONS_LIMIT;
 
     #[derive(Debug)]
     struct RejectWrites;
@@ -1714,7 +1713,7 @@ mod tests {
         assert_eq!(relay.pending_handshakes_limit.available_permits(), 128);
         assert_eq!(
             relay.connections_limit.available_permits(),
-            Semaphore::MAX_PERMITS
+            DEFAULT_CONNECTIONS_LIMIT
         );
         assert_eq!(relay.queries_per_minute, 1_200);
         assert_eq!(relay.auth_events_per_minute, 30);