Mock REST APIs: configured routes with static or templated responses

What a mock API does

A mock API is a temporary HTTP endpoint that returns responses you configure. Use it to develop a client before the real API exists, to reproduce an error status or a slow response, or to give a test suite a stable fake dependency. Responses are static text or simple templates; no user code runs.

Create a mock API

POST /api/mocks with a JSON body containing a name and routes. Settings such as visibility and ttlSeconds go in the query string. The response includes endpointUrl and a managementToken, plus an accessToken when the mock is private.

curl -X POST 'https://socket.help/api/mocks?visibility=public' \
  -H 'Content-Type: application/json' \
  -d '{
    "name": "Users",
    "routes": [
      { "method": "GET", "path": "/users/:id", "status": 200,
        "body": "{\"id\":\"{{path.id}}\"}", "template": true },
      { "method": "POST", "path": "/users", "status": 503,
        "body": "{\"error\":\"unavailable\"}", "delayMs": 1500 }
    ]
  }'

# 201 Created
{
  "id": "MOCK_ID",
  "managementToken": "MANAGEMENT_TOKEN",
  "expiresAt": "2026-10-27T13:00:00.000Z",
  "visibility": "public",
  "accessVersion": "ACCESS_VERSION",
  "endpointUrl": "https://socket.help/mock/MOCK_ID"
}

curl https://socket.help/mock/MOCK_ID/users/42
# {"id":"42"}

Route fields

A configuration has a name of up to 80 characters and 1 to 20 routes. The whole configuration must fit in 80 KiB.

How requests are matched

Call routes under endpointUrl, for example https://socket.help/mock/MOCK_ID/users/42. A route matches when the method is equal, the path has the same number of segments with equal literal segments, and the condition (if any) holds. Trailing slashes are ignored.

The first route in configuration order wins. If no route has the request method, HEAD falls back to a GET route, then any method falls back to an ANY route. No match returns 404 with {"error":"No matching mock route."}.

A condition compares one request header, query parameter or top-level JSON body field to an exact string. Use conditions to return different responses from the same path, for example a 401 route and a 200 route for the same path selected by an Authorization value.

Response content

Content-Type defaults to application/json. Allowed types are application/json, application/problem+json, application/xml, text/plain, text/csv and text/event-stream, optionally with ; charset=utf-8. Responses with status 204, 205 or 304 and HEAD requests send no body.

Templates replace {{path.name}}, {{query.name}} and {{body.name}} with the request value. In JSON templates, placeholders must sit inside strings and values are JSON-escaped. Missing values become empty strings. Each inserted value is limited to 4,096 characters and the rendered body to 64 KiB. Templates do not support XML or streaming.

Streaming routes must use GET or ANY with status 200. Each line of the body is sent as one chunk, or as one server-sent event with sequential id and event: message, at the configured interval. A stream allows up to 20 lines of 4 KiB and five seconds of delivery.

Read, update and delete

GET /api/mocks/{id} returns the configuration, visibility, accessVersion, expiresAt, uses (the number of requests received) and endpointUrl. PUT /api/mocks/{id} replaces the whole configuration with a new valid body and returns 204. DELETE /api/mocks/{id} removes it immediately.

curl -X PUT https://socket.help/api/mocks/MOCK_ID \
  -H "Authorization: Bearer $MANAGEMENT_TOKEN" \
  -H 'Content-Type: application/json' \
  -d '{"name":"Users","routes":[{"method":"ANY","path":"/health","status":200,"body":"ok","headers":{"content-type":"text/plain"}}]}'
# 204 No Content

Limits

Each mock API accepts up to 120 requests per minute in total; per-route requestsPerMinute applies on top. When stream capacity is reached, new streams get 503 with Retry-After: 5.