NIP-46 nostrconnect:// URL Parameter Format

Problem

When implementing NIP-46 client-initiated connections (nostrconnect://), signer apps may fail to recognize the URL if app metadata is passed as a JSON object instead of separate query parameters.

Context / Trigger Conditions

• Signer app (Amber, nsec.app, nsecBunker) shows error or fails silently when scanning/pasting URL
• URL contains metadata={"name":"...","url":"..."} format
• QR code generates successfully but signer doesn't connect
• Other parameters (relay, secret, perms) appear correct

Solution

Wrong (metadata JSON object):

nostrconnect://<pubkey>?relay=wss://relay.example.com&secret=abc123&metadata={"name":"MyApp","url":"https://myapp.com","icon":"https://myapp.com/icon.png"}&perms=sign_event

Correct (separate parameters per NIP-46):

nostrconnect://<pubkey>?relay=wss://relay.example.com&secret=abc123&name=MyApp&url=https://myapp.com&image=https://myapp.com/icon.png&perms=sign_event

Code fix example (Dart):

// WRONG - Don't bundle in metadata JSON
if (metadata.isNotEmpty) {
  final metadataJson = jsonEncode(metadata);
  params.add('metadata=${Uri.encodeComponent(metadataJson)}');
}

// CORRECT - Use separate params as specified in NIP-46
if (appName != null && appName.isNotEmpty) {
  params.add('name=${Uri.encodeComponent(appName)}');
}
if (appUrl != null && appUrl.isNotEmpty) {
  params.add('url=${Uri.encodeComponent(appUrl)}');
}
if (appIcon != null && appIcon.isNotEmpty) {
  params.add('image=${Uri.encodeComponent(appIcon)}');
}

Verification

1. Generate a nostrconnect:// URL
2. Verify URL contains name=, url=, image= as separate params (not metadata=)
3. Test with signer app (Amber Android, nsec.app web, or nsecBunker)
4. Signer should show app name and prompt for approval

NIP-46 Spec Reference

From NIP-46:

Additional information should be passed as query parameters:

• name (optional) - the name of the client application
• url (optional) - the canonical url of the client application
• image (optional) - a small image representing the client application

The spec does NOT mention a metadata parameter - each field is a separate query param.

Notes

• All query parameter values should be URL-encoded
• The relay parameter can appear multiple times for multiple relays
• The secret parameter is REQUIRED for nostrconnect:// (not optional like bunker://)
• Some signer apps may be more lenient than others - always follow spec exactly
• Note the param is image, not icon (easy to confuse with the metadata field name)

References

• NIP-46 Nostr Remote Signing