Deterministic mock endpoints for API testing.
Apidog is a full API lifecycle platform. mockapi.dog is a focused mocking tool. If you need a mock endpoint in seconds - not a design suite - this is it.
- Simulate specific HTTP error codes, latency, and intermittent failures on demand
- Test SSE/streaming response handling with OpenAI-compatible endpoints
- Stable URLs - no project setup, no desktop app required
A focused mocking tool for developers who write tests, not design documents.
The Problem
You need a mock endpoint. Not an API design tool. Not a documentation generator. Not an automated testing platform. A mock endpoint.
Apidog positions itself as Postman + Swagger + Stoplight + JMeter combined. It does API design, debugging, mock servers, automated testing, documentation, and performance testing. Mocking is one small feature inside a massive suite.
To mock an endpoint in Apidog, you download the desktop app, create an account, create a project, define an API specification, and then generate a mock from it. That's a design-first workflow. Sometimes you just need a URL that returns JSON.
Scenario
A QA engineer writing integration tests needs three endpoints: one that returns 200, one that returns 500 thirty percent of the time, and one that returns 401 when a specific header is missing. She needs these accessible from her CI runner without installing a desktop app, creating an account, or defining an API specification.
The Solution
mockapi.dog provides hosted mock endpoints with deterministic behavior. No project, no spec, no account.
Create an endpoint that returns any HTTP status code. Add a delay in milliseconds. Set a random error rate. Configure conditional errors that trigger only when a specific header is present.
For streaming tests, create LLM endpoints in OpenAI, Anthropic, or generic SSE formats. Tokens stream over Server-Sent Events exactly like the production APIs.
Endpoints are hosted and stable. They work from your local machine, your CI runner, and your staging environment. No server to maintain. No app to install.
Feature Breakdown
Configurable error rates
Set an endpoint to fail 10%, 30%, or 50% of the time with a specific error status code. Test retry logic, circuit breakers, and backoff against realistic intermittent failures.
Conditional error responses
Define a header name, value, and error status code. When the request includes that header with that value, the endpoint returns the error. Test auth flows and feature flags with a single endpoint.
Millisecond-precision delay
Add 100ms, 500ms, 2000ms, or any delay you need. Test timeout handling, loading states, and performance thresholds. Verify your app handles "slow" vs "down" correctly.
LLM streaming for integration tests
Your test suite needs to verify streaming parser behavior. Create a mock that streams tokens in OpenAI format. Assert on the parsed output. No API key. No rate limit. No cost per test run.
Stable hosted endpoints
Endpoints persist across sessions. Run your test suite today and next month against the same URL. No local server to start. No Docker to boot. No port conflicts.
All HTTP methods supported
GET, POST, PUT, DELETE, PATCH, HEAD, OPTIONS. Mock every method your application calls. Test the full request/response cycle for each one.
mockapi.dog vs Apidog
| Feature | mockapi.dog | Apidog |
|---|---|---|
| What it is | Mock API tool | Full API lifecycle suite |
| Setup time | Seconds | Minutes |
| Signup required | ||
| Desktop app required | Yes (recommended) | |
| LLM streaming (SSE) | ||
| Error rate simulation | Yes (configurable %) | Limited |
| Conditional errors | Yes (header-based) | |
| Delay injection | ||
| API design tools | ||
| Auto-generated docs | ||
| Automated testing | ||
| Cost | Free, no limits | Freemium |
Honest tradeoffs
mockapi.dog does not provide API design, documentation generation, automated test runners, or team collaboration features. If your workflow requires designing APIs visually, generating documentation from specs, or running automated test scenarios, Apidog covers those needs. mockapi.dog is for developers and QA engineers who need hosted mock endpoints with configurable behavior and zero overhead.
Use Cases
Testing retry logic with intermittent 500 errors
Set an endpoint to return 500 errors 25% of the time. Run your API client against it 100 times. Verify that your retry mechanism handles each failure and eventually succeeds.
Validating timeout handling
Create an endpoint with a 5-second delay. Set your HTTP client's timeout to 3 seconds. Verify that your app shows the right error message, doesn't hang, and doesn't retry indefinitely.
Testing authentication error flows
Create an endpoint with a conditional error: when the Authorization header is missing, return 401. When it's present, return 200 with user data. Test both paths with one endpoint.
Verifying streaming response parsing
Create an LLM streaming mock in OpenAI format. Write an integration test that connects, receives tokens, and asserts on the final assembled content. Run it in CI without API credentials.
Developer Experience
Creating a test endpoint takes seconds, not hours of infrastructure work.
There is no test server to configure. No stub mapping files to maintain. No desktop app to download. No CI pipeline step that starts a mock server before running tests.
Open mockapi.dog. Configure the response behavior: status code, body, delay, error rate, conditional errors. Save. Use the URL in your test.
The endpoint is hosted, available from your machine and your CI runner, and persists between test runs.
Pricing
Free. No limits. No signup.
No request quotas. No test-run caps. No paid tier for "advanced" features like error simulation.
Every feature is available to every user, immediately. This tool is maintained by a solo developer who believes testing infrastructure should be accessible, not gated.
Ready to start?
You need a mock endpoint, not an API design suite. Create a test endpoint on mockapi.dog. It's free, it's hosted, and it's ready in seconds.