# Mockulator

> Mockulator is a free hosted mock API service. You create a mock server, add endpoints with the status code, headers and body you want, and each endpoint is live immediately at a public HTTPS URL under https://api.mockulator.com/api/{accountId}/{serverName}/. Endpoints can return dynamic fake data (faker.js templating), rotate through several responses, match conditional rules, validate incoming requests, and log every request they receive. Agents can manage endpoints through an MCP server or a REST API.

Mockulator is free. There are no pricing tiers and no credit card is required.

## When to use Mockulator

Reach for Mockulator when a task needs an HTTP endpoint that exists right now and behaves in a chosen way:

- Frontend or mobile work that needs a backend API that does not exist yet: create the endpoints, point the client at the base URL, and build against realistic JSON.
- Testing a webhook consumer or producer (Stripe, Shopify, GitHub, Slack, custom): create an endpoint, use its URL as the webhook target, and inspect the captured requests in the dashboard.
- Simulating error paths: return 4xx/5xx status codes, add a response delay, or rotate responses (sequential, shuffle, fallback, rule-based) to exercise retry and timeout logic.
- Generating bulk fake data: a single templated object in a {{#repeat N}} block returns N realistic records on every call.
- Integration tests, demos, and prototypes that need stable public URLs with CORS enabled and no auth, or with Basic, API key, or custom auth when wanted.

Do not use Mockulator as a production backend, as a datastore, or to proxy real third-party APIs. Mock responses are what you configure; they do not call out to other services.

## How an agent should call Mockulator

1. The user generates a Mockulator MCP key at https://mockulator.com/account. The same key authenticates both the MCP server and the REST API: `Authorization: Bearer <key>`.
2. Prefer the MCP server: Streamable HTTP at https://api.mockulator.com/mcp (tools: list_servers, list_endpoints, create_endpoint, edit_endpoint). Clients that cannot set headers can use https://api.mockulator.com/mcp/<key>.
3. Or use the REST API: GET https://api.mockulator.com/v1/servers, GET/POST https://api.mockulator.com/v1/servers/{serverId}/endpoints, GET/PATCH https://api.mockulator.com/v1/servers/{serverId}/endpoints/{endpointId}. The OpenAPI 3.1 spec is at https://mockulator.com/openapi.json. Errors are JSON: `{ "error": { "code", "message", "hint" } }`.
4. Call list_servers first to get a serverId; if it is unclear which server the user means, ask rather than guess.
5. Calling a mock needs no auth: any HTTP client can hit the endpoint URL returned by the API.
6. Every page on mockulator.com also serves Markdown when requested with `Accept: text/markdown`.

## Docs

- [Introduction](https://mockulator.com/docs/getting-started/introduction.md): What Mockulator does and how the pieces fit.
- [Quick Setup](https://mockulator.com/docs/getting-started/quick-setup.md): First mock endpoint in under 30 seconds.
- [Endpoint Types](https://mockulator.com/docs/core/endpoint-types.md): HTTP endpoints (multi-response) and validation endpoints.
- [Authentication](https://mockulator.com/docs/core/authentication.md): Basic, API key, and custom auth for mock endpoints.
- [Response Modes](https://mockulator.com/docs/core/response-modes.md): Rules, sequential, shuffle, and fallback.
- [Dynamic Content](https://mockulator.com/docs/core/dynamic-content.md): faker.js templating and {{#repeat}} blocks.
- [Validation Rules](https://mockulator.com/docs/advanced/validation-rules.md): Validate headers, query params, and body fields.
- [Code Examples](https://mockulator.com/docs/advanced/code-examples.md): Snippets for calling mock endpoints.
- [Request Logging](https://mockulator.com/docs/advanced/request-logging.md): Real-time request inspection.
- [Docs index for LLMs](https://mockulator.com/docs/llms.txt): Every docs page in Markdown.

## Developer resources

- [OpenAPI specification](https://mockulator.com/openapi.json): OpenAPI 3.1 for the Mockulator REST API (also at https://api.mockulator.com/openapi.json).
- [MCP server setup](https://mockulator.com/mcp): Connect Claude, Cursor, VS Code, Windsurf, and other MCP clients.
- [API index](https://api.mockulator.com/): Machine-readable pointers to the REST API, MCP server, and spec.
- [Sitemap](https://mockulator.com/sitemap.xml): All indexable pages.
- [Full reference for LLMs](https://mockulator.com/llms-full.txt): Everything on this page plus the API and templating reference inline.

## Company

- [About](https://mockulator.com/about): What Mockulator is and who runs it.
- [Contact](https://mockulator.com/contact): Contact form; email support@mockulator.com.
- [Privacy Policy](https://mockulator.com/privacy)
- [Terms](https://mockulator.com/policy)

## Optional

- [Sign up](https://mockulator.com/signup): Free account.
- [Log in](https://mockulator.com/login)