API Mock Response Generator
Define a simple response shape and generate a realistic mock JSON response - useful for frontend development before a real API exists.
Describe the shape of a response below (field names and types) and generate a realistic mock JSON response matching it.
Describe each field as "fieldName": "type". Supported types: string, number, integer, boolean, email, uuid, date, array<type>, nullable<type>, or a nested object.
Generation happens entirely in your browser - no data is sent to or stored on a server.
What Is an API Mock Response Generator?
This tool takes a simple description of a response shape - field names paired with a type such as string, number, boolean, array, or object - and generates a realistic sample JSON response matching it, without needing a real backend to exist yet.
Why Use This Tool?
Useful for frontend development against an API that is still being built, populating a UI prototype with realistic-looking data, or writing a test fixture quickly.
How to Use the API Mock Response Generator
- Define your shape as JSON, using a type name as each field's value - for example
{"id": "number", "name": "string", "active": "boolean", "tags": ["string"]}. - Click Generate to produce a mock response matching that shape.
- Click Generate again for a fresh set of sample values.
Supported Types
string, number, integer, boolean, array (as ["type"]), nested object, and a nullable variant of any type (as "string|null").
Related Tools
Once you have a mock response, use the API Response Formatter or JSON Validator to double-check its formatting.