Looking for a Mockaroo alternative that doesn't cap your rows, ask for an account, or upload your schema to a server? The JSON Dev Tools Mock Data Generator generates realistic, coherent mock data — JSON, NDJSON, or CSV — entirely in your browser. It's free, has no row limit, and uses a seed so your test data is reproducible.
No signup · nothing uploaded · works offline
Why look for a Mockaroo alternative?
Mockaroo is a capable, popular tool, but because it generates data on its servers, the free tier comes with the usual trade-offs of a hosted product: a cap on how many rows you can generate per run, daily request limits, and an account for saving schemas. You also send your field definitions — and any sample data — to a third party. For quick fixtures, sensitive schemas, or large datasets, a client-side tool removes all of that friction.
JSON Dev Tools vs. a hosted generator
| JSON Dev Tools (this tool) | Hosted generators (e.g. Mockaroo) | |
|---|---|---|
| Price | Free, no tiers | Free tier + paid plans |
| Row limit | None (limited only by your RAM) | Row / daily caps on the free tier |
| Where it runs | 100% in your browser | On their servers |
| Your data | Never leaves your device; works offline | Schema & samples uploaded |
| Account | None required | Account for saved schemas / API |
| Reproducible seed | Yes — deterministic output | Varies |
| Coherent rows | Yes (email matches name, address is one place) | Varies by field setup |
| Formats | JSON, NDJSON, CSV | JSON, CSV, SQL, Excel, and more |
| Hosted mock API | No | Yes |
Mockaroo™ is a product of its respective owners and isn't affiliated with JSON Dev Tools. Plan limits and features change — check their site for current details.
What you get
- No row cap. Generate 10 rows or 1,000,000 — it runs locally, so there's no server quota.
- Private by default. Your schema and any pasted sample stay in the browser; nothing is uploaded, and it works offline once loaded.
- Coherent data. Each row holds together:
emailandusernamederive from that row's name,city/state/zip/countrycome from one real location, andupdatedAtnever precedescreatedAt. - Reproducible. Set a seed and the same schema yields byte-identical output every run — perfect for fixtures and snapshot tests.
- Three ways in. Build fields visually, paste a JSON sample to clone its shape, or paste a JSON Schema.
- Export anywhere. JSON array, NDJSON (one object per line, great for bulk import), or CSV.
How to generate mock data (no signup)
- Open the Mock Data Generator.
- Add fields with the picker (UUID, name, email, city, price, date, enum, nested objects/arrays…), or paste a real JSON sample / JSON Schema.
- Set the row count, an optional seed, and a format (JSON / NDJSON / CSV).
- Click Generate, then Copy or Download. Done — no account, nothing sent anywhere.
When Mockaroo might still be the better choice
To be fair: if you need a hosted mock REST API, server-side exports like SQL or Excel, an enormous built-in field library, or team-shared saved schemas tied to an account, Mockaroo is built for that. This tool is the right pick when you want fast, private, unlimited JSON/NDJSON/CSV generation without uploading anything or signing up.
Frequently Asked Questions
Is this Mockaroo alternative really free?
Yes. It is completely free with no account, no paywall, and no usage limits. It runs entirely in your browser, so there is no server cost to pass on — generate as many rows as your machine can handle.
Is there a row limit like Mockaroo's free tier?
No row cap. Hosted generators usually limit rows per run or per day on their free tier because generation happens on their servers. Here, generation runs locally in your browser, so you can produce thousands or millions of rows without an account — the only limit is your device's memory.
Does my data leave my browser?
No. Everything is client-side: the schema you build and any sample JSON you paste never leave your device, and the tool works offline once loaded. With a hosted service, your schema and sample data are sent to and processed on their servers.
Can I get reproducible data for tests?
Yes. Type any text into the seed box and generation becomes deterministic — the same schema and seed produce byte-identical output on any machine, which is ideal for fixtures and snapshot tests. Leave the seed blank for fresh random data each run.
Can I import an existing schema or JSON sample?
Yes. Besides the field picker, you can paste a real JSON object or array and the tool infers a generator per field, or paste a JSON Schema (draft-07 subset) and generate conforming data. Export as a JSON array, NDJSON, or CSV.
What does Mockaroo do that this doesn't?
Mockaroo is a mature hosted product with a very large field-type library, saved schemas tied to an account, REST mock endpoints, and server-side formats like SQL and Excel. This tool focuses on fast, private, unlimited generation of JSON/NDJSON/CSV in the browser; if you need hosted mock APIs or SQL export, Mockaroo may fit better.