DevPeek

WebSocket sessions and WS Flow

DevPeek records proxied WS / WSS connections alongside HTTP requests, with handshake details, frame search, simulated sending, text-frame interception, and HAR export. WS Flow can replace the upstream with a virtual server.

WebSocket sessions and single-file WS Flow are available in the 1.4.0 Beta. Multi-file workspaces and upstream forwarding remain subject to in-app availability.

Inspect a WebSocket connection

The client must use the DevPeek proxy. WSS also requires CA trust and a host included in SSL decrypt scope.

  1. Select the client tab in Capture and filter for WebSocket content.
  2. Expand WebSocket Connections below the request list and select a connection.
  3. Use Overview for URL and state, Handshake for Upgrade details, and Session for frames.
  4. The HTTP Upgrade row and connection remain secondarily highlighted for cross-reference.
DevPeek WebSocket session details with a selected text frame
Expand a WebSocket connection, filter frames in Session, and inspect the selected frame.

Filter, inspect, and send frames

  • Filter by client/server direction and search frame content.
  • Hide Ping, Pong, and Close control frames; large sessions load on demand.
  • Inspect or copy a text frame, or fill it into the composer, edit it, and send again.
  • While Open, simulate either client or server frames. Closed connections are read-only.

Intercept text frames

Text-frame interception is useful for one-off message edits without writing a Flow.

  1. Enable Intercept text frames in the Session tab.
  2. New text frames pause before reaching the peer.
  3. Edit and resume a paused frame, or drop it.

Export HAR

Export all frames, the current filter, the latest 500 / 2000 / 10000 frames, or a range around one business frame. Ping, Pong, and Close are omitted. Review secrets and personal data before sharing.

Use WS Flow as a virtual server

When `# ws` matches and `# upstream off` is set, DevPeek skips the real upstream and responds through Flow conditions, returns, scopes, and lifecycle rules.

  1. Open the WS Flow side panel or Proxy → WS Flow settings.
  2. Create a single-file rule with a title, `# ws`, and Flow body.
  3. Validate first. E errors block apply; review W warnings for your scenario.
  4. Save, enable the rule, and reconnect the client.
DevPeek WS Flow editor with a validation warning
Configure the endpoint, upstream behavior, and response rules, then review validation before applying.

Read the WebSocket Mock guide · Open the full .dpws reference

Troubleshooting

  • Handshake but no readable WSS frames: check CA trust, SSL include/exclude rules, and certificate pinning.
  • Flow does not match: enable it, reconnect, and compare `# ws` with the actual URL.
  • Immediate disconnect: review validation, `# ping auto`, `# idle-timeout`, and unmatched behavior.
  • Intercept disabled: select a connection that is still Open.