Error Message Generator
Generates realistic HTTP error codes and messages for testing and mocks
About this generator
When building error-handling tests or populating a mock API, you need varied, realistic HTTP errors — not the same 500 repeated ten times. This generator returns a shuffled selection of status-code-plus-message pairs from the ten errors most APIs encounter. One input controls the output: the count field (1–10) sets how many to return. The generator draws from a fixed pool — 400, 401, 403, 404, 409, 422, 429, 500, 502, and 503 — shuffles them, and returns the requested number. Each entry pairs the numeric code with a concise plain-English description. Drop the output into test fixtures to exercise error-handling branches, populate a mock API, or copy descriptions into API documentation. Adjust any user-facing message wording to match your application's tone and add recovery hints where appropriate.
How to use
- Choose how many error messages you want.
- Click Generate to produce a shuffled set.
- Copy the codes and messages into your tests, mocks, or docs.
- Adjust the wording to match your application.
Use Cases
- •Seeding error-handling test cases with varied responses
- •Populating a mock API with realistic failure messages
- •Documenting the possible errors an endpoint can return
- •Building a reference of common HTTP status codes
- •Explaining error meanings to less technical teammates
Tips
- →Use a varied set to test that your error handling covers each case.
- →Avoid leaking internal detail in user-facing error messages.
- →Add a recovery hint to user-facing errors where you can.
- →Match the message tone to the rest of your application.
FAQ
which HTTP status codes are included in the pool
Ten codes: 400, 401, 403, 404, 409, 422, and 429 on the client-error side, plus 500, 502, and 503 on the server-error side. The generator shuffles these on each run and returns however many you request, up to ten.
can I request more than ten error messages
No — the pool contains exactly ten distinct errors, so the maximum count is ten. Requesting more is clamped without repeating entries.
are the descriptions production-ready
They are accurate starting points. For user-facing errors, adjust the tone, avoid exposing internal detail, and add a hint about what the user can do next — the generated descriptions explain the failure but do not suggest a recovery action.
does the order of returned errors have meaning
No — the pool is shuffled randomly on each run. If you need a specific set of codes for a test, copy the output and sort or filter it manually.
You might also like
Popular tools from other categories that share themes with this one.