Use this command to install Mockzilla with WinGet:
winget install --id=Mockzilla.Mockzilla -e
Mockzilla is an OpenAPI mock engine designed to generate API mocks with realistic responses, configurable latency, error codes, and more. It enables developers to create accurate and functional API simulations directly from OpenAPI specifications, eliminating the need for manual configuration or external infrastructure.
Key Features:
Realistic Response Generation: Automatically produces meaningful responses based on your OpenAPI schema.
Configurable Latency & Errors: Simulate network delays and error scenarios to test application resilience.
Upstream Proxy with Fallback: Route requests to real backends while providing mock fallbacks for unavailable endpoints.
Selective Endpoint Overrides: Combine auto-generated mocks with custom handlers for specific routes.
Request Validation: Ensures all incoming requests adhere to your OpenAPI specification.
No-Code Setup: Run directly from OpenAPI specs without additional configuration.
Audience & Benefit:
Ideal for developers, testers, and teams working on API-driven projects. Mockzilla accelerates development by enabling local testing of APIs before backend implementation, supports CI/CD pipelines with reliable integration tests, and reduces dependency risks by simulating external services. It is particularly beneficial for scenarios involving multiple third-party APIs, payment gateways, or crypto exchanges, as well as offline environments where internet access is unavailable.
Available via winget for easy installation, Mockzilla empowers teams to streamline their API development workflows with precision and efficiency.
README
Mockzilla
Mockzilla is an open-source mock server for OpenAPI specifications, validated against 2,200+ real-world OpenAPI specifications across 98,000+ endpoints. Point it at a spec and get a running API mock server in seconds - no code, no configuration, no separate infrastructure. It generates realistic responses from your schema, validates incoming requests against the spec, and can proxy real backends with automatic mock fallback so you can mix real and mocked endpoints in the same server. Use it locally during development, in CI pipelines for integration testing, or embed specs into a portable binary for offline and air-gapped environments.
Goals
Generate realistic mock APIs directly from OpenAPI specs, not a custom DSL.
Combine multiple third-party APIs into a single local mock server.
Catch contract drift early by validating every request against the spec.
Features
Multiple APIs on one server - each spec becomes a service with its own URL prefix
Upstream proxy - forward to real backends with fallback to mocks
Latency & error simulation - test how your app handles delays and failures
Custom middleware - modify requests/responses on the fly
Response caching - cache GET responses for consistency
Request validation - validate against OpenAPI spec
Static responses - define custom responses for any path outside your OpenAPI spec
Selective overrides - override specific endpoints with static responses or custom handlers while the rest of the OpenAPI spec stays auto‑generated
Real-World Validation
Mockzilla continuously generates and validates data against 2,200+ real-world OpenAPI specifications:
If you need per-PR simulation URLs, team-shared stable endpoints, or zero-config GitHub Action setup without running your own server, mockzilla.org is the hosted version built on the same engine.
AI and MCP tooling
Mockzilla ships an MCP server, so AI tools like Claude Code, Cursor, and Gemini CLI can launch mock APIs directly from any OpenAPI definition. Point the agent at a spec and it spins up a Mockzilla server under the hood, letting you iterate on client code or integration tests without leaving the editor.
