mock-server

name: mock-server description: "Spin up mock API servers for frontend development and testing: static responses, record/replay real API calls, dynamic response generation." category: backend maturity: stable tags: [mock-api, record-replay, openapi, rest, stubbing]

Spin up mock API servers for frontend development and testing: static responses, record/replay real API calls, dynamic response generation.

When to Use

Developing frontend without a backend
Testing against mock APIs
Recording real API responses for replay
Isolating frontend tests from backend dependencies

Scripts

mock-server.py

Python mock API server with zero dependencies.

python3 scripts/mock-server.py --config routes.json --port 8080

Config format:

{
  "routes": [
    {
      "method": "GET",
      "path": "/api/users",
      "status": 200,
      "body": [{ "id": 1, "name": "Alice" }]
    },
    {
      "method": "POST",
      "path": "/api/users",
      "status": 201,
      "body": { "id": "{{random_id}}", "created": "{{timestamp}}" },
      "delay_ms": 100
    }
  ]
}

Dynamic templates: {{random_id}}, {{timestamp}}, {{request.body.name}}, {{uuid}}

Supports: regex path matching, custom headers, response delays.

record-replay.py

Record real API calls and replay them.

# Record
python3 scripts/record-replay.py --mode record --target https://api.example.com --port 8081 --output recordings.json

# Replay
python3 scripts/record-replay.py --mode replay --input recordings.json --port 8081

mock-config-gen.sh

Generate mock config from Express/Fastify routes or OpenAPI spec.

bash scripts/mock-config-gen.sh --source routes/ --output mock-routes.json
bash scripts/mock-config-gen.sh --source openapi.yaml --output mock-routes.json

References

mocking-strategies.md — When to mock vs use real APIs