Best Free Online Developer Tools to Use in 2026
A practical, opinionated list of the best free online developer tools worth using in 2026, organized by category so you can find what you need fast.
Aug 08, 2026
JSON Schema Faker
Generate realistic mock JSON data from JSON Schema definitions. Supports nested objects, arrays, enums, and custom formats.
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What is JSON Schema Faker?
JSON Schema Faker generates realistic mock JSON data from a JSON Schema definition. Instead of manually creating test data, you define the structure with a schema and this tool produces sample data that matches your specification.
It supports all JSON Schema draft versions (draft-04 through 2020-12), nested objects, arrays with min/max items, enums, string formats (email, date, uuid, uri, ipv4, ipv6, etc.), numbers with minimum/maximum, and booleans. The generated data is deterministic but randomized — useful for testing, prototyping, and demos.
How to Use
- Paste JSON Schema — Enter a valid JSON Schema definition in the left panel. Click "Example Schema" to load a sample with nested objects, arrays, enums, and formats.
- Set Count — Choose how many mock objects to generate (1-50). For array-type schemas, count controls how many items to produce.
- Generate — Click "Generate Mock Data" to produce realistic sample data that conforms to your schema.
- Copy or Download — Use the copy button or download the generated JSON as a file for use in your tests or prototypes.
Frequently Asked Questions
What JSON Schema features are supported?
The tool supports string/ number/ integer/ boolean/ array/ object types, nested properties, required fields, enums, string formats (email, date, date-time, uuid, uri, hostname, ipv4, ipv6, json-pointer), minimum/maximum for numbers, minLength/maxLength for strings, minItems/maxItems for arrays, pattern properties, additionalProperties, and $defs/definitions references.
Is the generated data truly random?
The data uses a random seed for variety, but values are constrained by your schema constraints. Strings with format specifications (like "email" or "date") produce format-valid values. Enums randomly select from the defined values. Numbers respect minimum/maximum boundaries.
What is the difference between this and the JSON Schema Generator?
The JSON Schema Generator creates a JSON Schema from existing JSON data. This tool (JSON Schema Faker) does the reverse — it generates mock JSON data from a JSON Schema. They are complementary tools: use the Generator to create schemas from data, then use the Faker to produce test data from schemas.
Is my data stored?
No. Everything runs entirely in your browser. Your data is never sent to any server.
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