Mock Error Payload Generator

Runs in browser Mocking

Given a list of fields, produce error payloads with per-field messages and codes in several conventions (Laravel, Django REST, ASP.NET, JSON:API) to test error rendering.

TEST DATA ONLY — all generated names, contacts, identifiers and numbers are synthetic and do not belong to real people or accounts.
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What does a good API error response look like?

A good API error uses the right status code and a consistent, machine-readable body. RFC 9457 (Problem Details) standardises that body: a type URI, a short title, the status, a human-readable detail and an instance identifier, in application/problem+json. It tells the caller what went wrong and how to fix it without exposing stack traces, SQL or internal paths.

How to use Mock Error Payload Generator

  1. List the form or API field names.
  2. Choose the convention, number of payloads and subset mode.
  3. Generate and feed the payloads to your form error rendering tests.

Mock Error Payload Generator features

  • Field-level error payloads in Laravel, Django REST, ASP.NET, JSON:API, Google, AWS, Stripe, RFC 9457, JSend, simple and GraphQL conventions
  • Bulk generation: all fields, one field at a time or random subsets
  • Codes and messages inferred from field names
  • Field error catalogue table for quick review
  • Seedable for stable snapshot tests

Mock Error Payload Generator example

Django REST payloads, one field at a time

Input:

Fields: email, password
Convention: Django REST, mode: one field at a time

Output:

[
  { "case": 1, "invalidFields": ["email"], "status": 422, "body": { "email": ["Email must be a valid email address."] } },
  { "case": 2, "invalidFields": ["password"], "status": 422, "body": { "password": ["Password must be at least 10 characters."] } }
]

Frequently asked questions about Mock Error Payload Generator

What is a field-level error payload?

The response a form receives when several inputs fail validation: a map of field names to messages (Laravel, Django REST), an errors dictionary with a traceId (ASP.NET), pointer-based errors (JSON:API), fieldViolations (Google) and more.

What does bulk mode do?

It produces many payloads at once — every field invalid, one field at a time, or random subsets — so you can snapshot-test how your UI renders each combination.

Are codes and messages realistic?

They are inferred from the field names (email → invalid_format, password → too_short, terms → must_be_true, userId → not_found) with neutral, human-readable messages you can adapt.

References