Current limitations, known bugs, and planned improvements for Mock API Builder. We're transparent about what's not working perfectly yet.
These are by-design limitations of the mock API platform. They're not bugs, but important constraints to be aware of.
Default behavior: Generated mock data is ephemeral unless you enable stateful endpoints or use seeded contract data.
Stateful mocking: Enable stateful mode on an endpoint to persist collections across POST/PUT/DELETE. In production, state is stored in Postgres. See Stateful Mocking.
What this means: You can't request more than 100 records at once using ?limit=100.
Workaround: Use pagination with multiple requests. This is actually a best practice for real APIs too.
What this means: There are no SQL-style joins or arbitrary relationship queries. Depth-1 embeds via ?expand= are supported; nested expand and multi-hop joins are not.
Workaround: Use ?expand=posts to embed related rows on each parent (max 20 per relation). For deeper graphs, make separate requests and combine on the client. See Search & Filter APIs.
What this means: Free accounts are limited by per-route rate limits (typically 120–600 requests/minute) and a monthly mock-request quota of 10,000 requests.
Workaround: Implement caching on your frontend, or contact us if you need higher limits for a specific use case.
See our Rate Limiting Guide for best practices.
Issues that were recently fixed or improved.
Imported OpenAPI specs now preserve the original required array on export, and optional properties are omitted from generated mock data unless Faker randomly includes them.
The visual schema editor now uses per-row rendering so typing in one field no longer re-renders every row. For schemas with 50+ fields, JSON contract mode remains the fastest option.
Tip: Switch to JSON editor mode for very large schemas.
Expiry and future-date fields (for example expiresAt) now use UTC-safe generation so timestamps are always strictly in the future relative to request time.
Features and fixes we're planning to implement. Want to influence our roadmap? Check out Feature Requests.
REST, GraphQL, gRPC, and SOAP are available — one protocol per project. See Choosing a Protocol.
Webhook inbox, outbound subscriptions, and delivery logs are available. See Webhooks & Events.
ShippedComparison operators in query parameters are supported: ?price_gt=100, ?date_gte=2025-01-01, ?name_like=widget, and more. See Search & Filter APIs.
Workspace roles (Owner, Editor, Viewer) control project access. Invite existing users from the workspace Members tab, or send an email invite (mailto link + copy/revoke) for people not yet registered — pending invites grant no access until accepted. Public share links remain separate. See Workspaces & Collaboration.
Mock API Builder is tested and supported on the following browsers:
Note: Internet Explorer is not supported. Some features may not work properly on older browsers.
