diff --git a/src/components/PostEditor/PostRelaySelector.tsx b/src/components/PostEditor/PostRelaySelector.tsx
index 7c6ebb2..5a5601b 100644
--- a/src/components/PostEditor/PostRelaySelector.tsx
+++ b/src/components/PostEditor/PostRelaySelector.tsx
@@ -96,7 +96,11 @@ export default function PostRelaySelector({
                 ...cacheRelayList.originalRelays
                   .filter(relay => (relay.scope === 'both' || relay.scope === 'write') && isLocalNetworkUrl(relay.url))
                   .map(relay => relay.url)
-              ].filter(url => isLocalNetworkUrl(url))
+              ].filter(url => {
+                // Filter out invalid/empty URLs
+                if (!url || typeof url !== 'string' || url.trim() === '' || url === 'ws://' || url === 'wss://') return false
+                return isLocalNetworkUrl(url)
+              })
               const existingUrls = new Set(userWriteRelays.map(url => normalizeUrl(url) || url))
               const newCacheRelays = cacheRelays
                 .map(url => normalizeUrl(url) || url)
diff --git a/src/lib/event-metadata.ts b/src/lib/event-metadata.ts
index cedfc47..8ccc3eb 100644
--- a/src/lib/event-metadata.ts
+++ b/src/lib/event-metadata.ts
@@ -22,7 +22,9 @@ export function getRelayListFromEvent(event?: Event | null, blockedRelays?: stri
   const normalizedBlockedRelays = (blockedRelays || []).map(url => normalizeUrl(url) || url)
   
   event.tags.filter(tagNameEquals('r')).forEach(([, url, type]) => {
-    if (!url || !isWebsocketUrl(url)) return
+    // Filter out empty, invalid, or malformed URLs
+    if (!url || typeof url !== 'string' || url.trim() === '' || url === 'ws://' || url === 'wss://') return
+    if (!isWebsocketUrl(url)) return
 
     const normalizedUrl = normalizeUrl(url)
     if (!normalizedUrl) return
diff --git a/src/services/relay-selection.service.ts b/src/services/relay-selection.service.ts
index 21d09db..5588bc2 100644
--- a/src/services/relay-selection.service.ts
+++ b/src/services/relay-selection.service.ts
@@ -127,6 +127,13 @@ class RelaySelectionService {
     return this.filterBlockedRelays(deduplicatedRelays, context.blockedRelays)
   }
 
+  /**
+   * Validate that a URL is a valid, non-empty relay URL
+   */
+  private isValidRelayUrl(url: string | undefined | null): url is string {
+    return !!(url && typeof url === 'string' && url.trim() !== '' && url !== 'ws://' && url !== 'wss://')
+  }
+
   /**
    * Get relay list from IndexedDB cache (kind 10002 and 10432 merged)
    * If not in cache, fetch from relays before returning empty
@@ -162,9 +169,15 @@ class RelaySelectionService {
       if (cacheRelayListEvent) {
         const cacheRelayList = getRelayListFromEvent(cacheRelayListEvent)
         
+        // Filter out invalid/empty URLs before merging
+        const validCacheRead = cacheRelayList.read.filter(this.isValidRelayUrl)
+        const validCacheWrite = cacheRelayList.write.filter(this.isValidRelayUrl)
+        const validRelayRead = relayList.read.filter(this.isValidRelayUrl)
+        const validRelayWrite = relayList.write.filter(this.isValidRelayUrl)
+        
         // Merge read relays - cache relays first, then others
-        const mergedRead = [...cacheRelayList.read, ...relayList.read]
-        const mergedWrite = [...cacheRelayList.write, ...relayList.write]
+        const mergedRead = [...validCacheRead, ...validRelayRead]
+        const mergedWrite = [...validCacheWrite, ...validRelayWrite]
         const mergedOriginalRelays = new Map<string, { url: string; scope: 'read' | 'write' | 'both' }>()
         
         // Add cache relay original relays first (prioritized)