JSON Mock Generator — Generate Realistic Test Data

Generate realistic mock JSON data from a JSON Schema using Faker. Perfect for prototyping, testing, and populating demo environments with lifelike data. 100% client-side.

JSON Schema0 chars
Output—
Output:
🛡️Zero server logs. Mock generation runs 100% inside your browser.
🛠️Developer Tool Belt
More Json ToolsJSON to Excel ConverterJSON → TypeScriptJSON Unescape — Decode Escaped JSON StringsJSON → YAMLJSON Schema Generator — Draft-07 from JSONJSON Patch Generator — RFC 6902 Diff ToolOpenAPI Generator — Create 3.0.3 Specs from JSONJSON Flatten — Nested to Dot-NotationJSON Merge — Deep Merge Multiple ObjectsJSON → C# DTOJSON Escape — Encode JSON Strings SafelyJSON → Python ClassJSON Key Extractor — Extract All Keys & PathsJSON Random Generator — Faker-Powered Test DataJSON FormatterJSON Diff — Compare JSON Data OnlineJSON → SQLJSON Viewer — Explore & Navigate JSON TreesJSON Size Analyzer — Analyze JSON Structure & SizeJSON → Go StructView all json tools →
Other Essential ToolsApp Icon GeneratorFavicon GeneratorPlaceholder Image GeneratorSprite Sheet Generator

JSON Mock Generator — Generate Realistic Test Data

Generate realistic mock JSON data from a JSON Schema using Faker. Perfect for prototyping, testing, and populating demo environments with lifelike data. 100% client-side.

🔒 Client-side only⚡ Web Worker processing🌐 Works offline🛡️ Zero server logs

How to Use

  1. Define your JSON Schema in the input editor (or use the default template).
  2. Adjust the count and click Generate Mock to create realistic test data.
  3. Copy the generated data for testing, demos, or API development.

Frequently Asked Questions

Questions about this tool? We've got answers.

What data does the generator produce?

The generator uses Faker.js to produce realistic data including names, emails, phone numbers, addresses, and more — all matching your schema structure and type constraints.

Can I control the output size?

Yes. Use the count slider to control how many objects to generate. You can also set minimum/maximum values for arrays and strings in the schema itself.

Is my schema sent to any server?

No. All generation runs 100% inside your browser via a Web Worker.

Automated E2E Test Suite Logs

Our build systems validate edge-case processing under extreme conditions before each deployment.

Stability
100.0%
Passed
28/28
Env
V8-Sandbox
Engine: Vitest RunnerUpdated: 2026/7/16 02:08:13📦 Download Test Datasets
PASSgenerateMockData should generate data matching the schema structure
PASSgenerateMockData should generate integer for integer type
PASSgenerateMockData should generate string for string type
PASSgenerateMockData should generate boolean for boolean type
PASSgenerateMockData should handle nested objects
PASSgenerateMockData should handle benchmark schema with all types
PASSgenerateMockData should generate values from enum when specified
PASSgenerateMockData should generate different values on each call
PASSgenerateMockData should throw on empty input
PASSgenerateMockData should throw on invalid JSON
PASSgenerateMockData should throw on schema without type or properties
PASSJsonMockGeneratorTool renders Generate Mock button
PASSJsonMockGeneratorTool renders Regenerate button
PASSJsonMockGeneratorTool renders JSON Schema and Generated Data labels
PASSJsonMockGeneratorTool renders two textareas
PASSJsonMockGeneratorTool shows privacy strip
PASSJsonMockGeneratorTool shows error toast on Generate with empty input
PASSJsonMockGeneratorTool shows Clear toast on Clear All click
PASSJSON Mock Generator Worker Standard schema processing should generate mock data from simple schema
PASSJSON Mock Generator Worker Standard schema processing should handle nested schema with arrays
PASSJSON Mock Generator Worker Standard schema processing should generate from benchmark schema
PASSJSON Mock Generator Worker Standard schema processing should generate enum values from enum-schema
PASSJSON Mock Generator Worker Standard schema processing should propagate requestId correctly
PASSJSON Mock Generator Worker Standard schema processing should generate different output on successive calls
PASSJSON Mock Generator Worker Boundary Conditions & Error Handling should return error for empty input
PASSJSON Mock Generator Worker Boundary Conditions & Error Handling should return error for invalid JSON schema
PASSJSON Mock Generator Worker Boundary Conditions & Error Handling should return error for empty object input
PASSJSON Mock Generator Worker Performance Benchmark should process benchmark schema within acceptable limits
⏱️ 0.18ms📦 1.5KB🎚️ Max Nesting: 3🌿 AST Nodes: 48🛡️ V8 Heap: Healthy
$ codecaven-validator --scope=tool● CLUSTER COMPLIANT

Tool Changelog & Updates

v1.2.02026-06-12
  • Fix: Fixed Faker path resolution — the tool now correctly reads the "faker" field in JSON Schema property definitions and calls the corresponding Faker.js method for realistic data generation.
  • Feature: Added Load URL button for loading schemas from remote URLs.
  • UX: Fixed i18n keys for Generate and Regenerate buttons.
1.1.02026-06-11
  • Feature: Added Web Worker thread-isolated test suite covering schema-based mock generation, nested object/array handling, enum value selection, and requestId propagation.
  • Test: Introduced boundary error validation for empty inputs, malformed JSON schemas, and empty object schemas.
  • Performance: Included large-schema (4MB+) stress benchmark with heap memory and execution time telemetry.
1.0.02026-06-10
  • Feature: Initial release