Dev
Error Message 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 your options above
- Click Generate
- Copy your result
Detailed instructions
- 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.
Try these next
More free tools from other corners of the catalog, picked by shared themes.