WebSocket

on_connect.send and each on_message[*].respond value are rendered as Go templates. The incoming message text is available as {{.request.body}}.

protocols:
  websocket:
    enabled: true
    port: 8081
    mocks:
      - id: ticker
        path: /ws/ticker
        on_connect:
          send: '{"event":"connected","path":"{{.request.path}}"}'
        on_message:
          - match: ping
            respond: '{"event":"pong","echo":"{{.request.body}}"}'

Binary frames

match_binary/respond_binary (and on_connect.send_binary) hold base64-encoded raw bytes and operate on binary (opcode 0x2) WebSocket frames — useful for Protobuf/MessagePack-framed APIs or other binary protocols. A rule with match_binary only matches binary frames and compares the decoded bytes exactly (no wildcard/regex); plain match/respond rules are unaffected and keep working exactly as before (including against binary frames, matched as text, for backward compatibility).

      - id: binary-echo
        path: /ws/binary
        on_connect:
          send_binary: "AQIDBA=="   # base64 for 0x01 0x02 0x03 0x04
        on_message:
          - match_binary: "3q2+7w==" # base64 for 0xDE 0xAD 0xBE 0xEF
            respond_binary: "yv4="  # base64 for 0xCA 0xFE

See also

• Configuration — matching, templated responses, state conditions, and scenarios shared by every protocol
• Fault Injection — this protocol's fault fields: close_code, message, delay, error_rate
• Management API — mocks for this protocol follow the same CRUD pattern as HTTP mocks (/api/mocks/{protocol})