Mock Data Generator — Users, APIs & JSON
Generate thousands of rows of realistic fake data for testing, prototyping, and QA. Supports custom JSON schemas, multiple locales, and deterministic seeding. Runs 100% locally—no data sent to a server, no login, and no email required.
Generate realistic mock data instantly with SolveBar's Mock Data Generator. Create fake users, APIs, UUIDs, and custom JSON schemas for testing—100% locally in your browser. No data leaves your device, no server processing, and absolutely no login or email required.
Why local mock data generation is mandatory for privacy
Most online mock data generators upload your schema definitions to a remote server to process them. If you are generating test data based on a proprietary database structure or internal API schema, using a cloud tool is a data leak. SolveBar generates all mock data locally in your browser using JavaScript, meaning your schema architecture never touches the internet.
Custom JSON Schemas vs. Pre-built Templates
Pre-built templates are fast, but custom JSON schemas give you exact control. Define your exact payload structure—nested objects, specific data types, arrays of items—and the generator will build the mock JSON to match it perfectly. This is essential for testing front-end components against realistic API responses without hitting a real backend.
Deterministic Seeding for Reproducible Tests
Random data is great for broad testing, but a nightmare for debugging. If a test fails on a randomly generated dataset, you can't reproduce it. By using a deterministic seed value, you can generate the exact same fake dataset every single time. Change the seed to get a new dataset, but keep the seed constant to freeze your test environment.
Fake Data for PCI-DSS Compliance Testing
Generating fake credit card numbers is strictly for software testing environments (like validating checkout form inputs or regex patterns). Real payment data must never be used in testing. Our tool generates mathematically valid card numbers that pass Luhn algorithm checks but are entirely synthetic, ensuring your QA process remains PCI-DSS compliant without risking real financial data.
Frequently Asked Questions
Does this tool send my data schema to a server?
No. All schema parsing and data generation runs entirely in your browser using client-side JavaScript. If you open your browser's Network tab, you will see zero outbound requests containing your data structure.
Can I generate fake data without creating an account?
Yes. SolveBar requires absolutely no login, email, or account creation. The tool is free, unrestricted, and works immediately on page load.
Are the fake credit card numbers real?
No. They are mathematically valid (they pass the Luhn checksum) so your software accepts them during testing, but they are not linked to any real bank account or funding source. They cannot be used for purchases.
How do I generate a specific JSON structure?
Input your JSON keys (e.g., 'firstName', 'address.city', 'tags[]') and select the desired data types for each key. The generator will output a perfectly formatted JSON array matching your exact schema.
Can I generate thousands of rows without freezing my browser?
Yes. The generator is optimized to handle large datasets efficiently. For massive data generation (100,000+ rows), we recommend using a deterministic seed to keep processing fast and memory usage low.