Generates random mock JSON from a JSON Schema.
Mock JSON from Schema generates random sample JSON data from a JSON Schema you paste in. Give it a schema describing the shape you want and it walks the structure to produce a fake JSON instance, making it handy for prototyping APIs, seeding tests, or filling out UI mockups. Everything runs in your browser, so it works offline once loaded.
No. The schema you paste is parsed and the mock JSON is generated entirely in your browser using the Web Crypto API. Nothing is uploaded or stored on a server.
It handles object, array, string, integer, number, boolean, and null types, plus enum (a random value is picked from the list). Object properties and array items are resolved recursively.
Strings return a random word from a small lorem-ipsum set, integers are a random value from 0 to 1000, numbers are a random float from 0 up to 1000, booleans are random true/false, and arrays get 1 to 3 generated items. Randomness comes from crypto.getRandomValues.
Only type, enum, properties, and items are interpreted. Keywords like format, minimum, maximum, required, or pattern are ignored, and any unknown or missing type resolves to null.
The input must be valid JSON. If the schema fails to parse, the tool reports an invalid JSON Schema error; an empty input simply produces no output.