diff --git a/.changeset/validate-relay-url.md b/.changeset/validate-relay-url.md
new file mode 100644
index 00000000..e820f851
--- /dev/null
+++ b/.changeset/validate-relay-url.md
@@ -0,0 +1,7 @@
+---
+"nostream": patch
+---
+
+fix(settings): validate `info.relay_url` is a usable absolute URL
+
+`validateSettings()` now rejects a `relay_url` that is not a valid absolute URL, parses with an empty host (scheme-only strings like `localhost:8008`), or uses a protocol other than `ws`/`wss`/`http`/`https`. Previously an invalid value started cleanly and then broke every HTTP request with `500 TypeError: Invalid URL`, including the Admin Console, leaving the bad setting fixable only by editing the file by hand. Found in #824.
diff --git a/src/utils/settings-config.ts b/src/utils/settings-config.ts
index 93fb9149..ee3f2aba 100644
--- a/src/utils/settings-config.ts
+++ b/src/utils/settings-config.ts
@@ -594,6 +594,21 @@ export const validateSettings = (settings: Settings): ValidationIssue[] => {
 
   if (!settings.info?.relay_url) {
     issues.push({ path: 'info.relay_url', message: 'relay_url is required' })
+  } else if (typeof settings.info.relay_url === 'string') {
+    try {
+      const parsed = new URL(settings.info.relay_url)
+
+      if (!parsed.host) {
+        issues.push({ path: 'info.relay_url', message: 'relay_url must include a valid host' })
+      } else if (!['ws:', 'wss:', 'http:', 'https:'].includes(parsed.protocol)) {
+        issues.push({
+          path: 'info.relay_url',
+          message: 'relay_url must use ws, wss, http, or https protocol',
+        })
+      }
+    } catch {
+      issues.push({ path: 'info.relay_url', message: 'relay_url must be a valid absolute URL' })
+    }
   }
 
   if (!settings.info?.name) {
diff --git a/test/unit/utils/settings-config.spec.ts b/test/unit/utils/settings-config.spec.ts
index d9179f35..dc0fe08b 100644
--- a/test/unit/utils/settings-config.spec.ts
+++ b/test/unit/utils/settings-config.spec.ts
@@ -98,6 +98,65 @@ describe('settings-config', () => {
     expect(issues.some((issue) => issue.path === 'network')).to.equal(true)
   })
 
+  it('accepts a relay_url with a valid ws/wss/http/https absolute URL', () => {
+    for (const relay_url of [
+      'ws://nostream.example.com:8008',
+      'wss://nostream.example.com',
+      'http://localhost:8008',
+      'http://nostream.example.com',
+      'https://nostream.example.com',
+      'https://nostream.example.com:8443',
+      'ws://[::1]:8008',
+      'wss://127.0.0.1',
+    ]) {
+      const issues = validateSettings({ info: { relay_url, name: 'test' } } as any)
+
+      expect(
+        issues.filter((issue) => issue.path === 'info.relay_url'),
+        `expected ${relay_url} to pass`,
+      ).to.be.empty
+    }
+  })
+
+  it('rejects a relay_url that is not a valid absolute URL', () => {
+    const issues = validateSettings({ info: { relay_url: 'nostream.example.com', name: 'test' } } as any)
+
+    expect(
+      issues.some(
+        (issue) => issue.path === 'info.relay_url' && issue.message === 'relay_url must be a valid absolute URL',
+      ),
+    ).to.equal(true)
+  })
+
+  it('rejects a scheme-only relay_url with no host', () => {
+    const issues = validateSettings({ info: { relay_url: 'localhost:8008', name: 'test' } } as any)
+
+    expect(
+      issues.some(
+        (issue) => issue.path === 'info.relay_url' && issue.message === 'relay_url must include a valid host',
+      ),
+    ).to.equal(true)
+  })
+
+  it('rejects a relay_url whose protocol is not ws/wss/http/https', () => {
+    for (const relay_url of [
+      'ftp://nostream.example.com',
+      'gopher://nostream.example.com:70',
+      'whttp://nostream.example.com',
+    ]) {
+      const issues = validateSettings({ info: { relay_url, name: 'test' } } as any)
+
+      expect(
+        issues.some(
+          (issue) =>
+            issue.path === 'info.relay_url' &&
+            issue.message === 'relay_url must use ws, wss, http, or https protocol',
+        ),
+        `expected ${relay_url} to be rejected for protocol`,
+      ).to.equal(true)
+    }
+  })
+
   describe('rate limit period validation', () => {
     const baseSettings = () =>
       ({