About formatvault
Private developer tools. No uploads. No accounts.
Developer tools should not require you to trust a stranger's server with your data. formatvault is a suite of everyday utilities — formatters, converters, decoders — that run entirely inside your browser. Your input never leaves your machine. Not when you format a JWT. Not when you convert a CSV. Not when you prettify a 100 MB JSON file. The data stays in your browser tab and disappears when you close it.
Why we built this
Most online developer tools follow the same pattern: you paste your data into a textarea, it gets sent to a server for processing, and a result comes back. That's fine for public data. It's a problem for everything else.
JWTs contain live session credentials. CSV exports contain customer records. JSON payloads from internal APIs contain database IDs, email addresses, and business logic. Pasting these into a random online tool means that data passes through infrastructure you have no insight into — even if the site says it deletes it immediately.
Modern browsers are powerful enough that server-side processing is simply not necessary for these tasks. formatvault takes the server out of the picture entirely.
How it works
formatvault is a static web application. When you visit a tool page, your browser downloads a self-contained JavaScript bundle from a CDN. From that point on, all processing runs locally in your browser tab using the same JavaScript engine your applications use.
- No server round-trips for data. Every format, parse, validate, and convert operation executes locally. There is no backend that receives your input.
- Large files stay local. Files above 1 MB are processed in a dedicated Web Worker using streaming parsers. A 200 MB CSV never leaves your machine — not even temporarily.
- Input content is never written to disk. Only UI preferences (theme, indent size) are saved to
localStorage. Your data exists only in JavaScript memory and is discarded when you close the tab. - Works offline. Once the page has loaded, all tools work without a network connection. The processing libraries are bundled with the app.
You can verify all of this yourself. Open DevTools → Network, then use any tool. You'll see zero outbound requests for your data.
What's included
formatvault currently ships 27 tools across three categories:
- Formatters & validators — JSON (with JSON5, JSONPath, and streaming up to 500 MB), CSV, YAML, TOML, and SQL (with multi-dialect support)
- Format converters — all major pairs between JSON, CSV, YAML, and TOML, plus JSON → TypeScript interface generation
- Utility tools — JWT decoder, Base64 encoder/decoder, URL encoder/decoder, hash generator (MD5/SHA-256/SHA-512), regex tester, JSON Schema generator, color picker, Unix timestamp converter, cron explainer, and number base converter
The technology
We believe in transparency. Here is exactly what runs inside your browser to process your data:
Our commitment
The client-side-only architecture is not a feature we can quietly remove later — it's structural. There is no server infrastructure to route your data through. We intend to keep it that way.
We will never add server-side data processing, user accounts that store your input, or tracking that identifies individual users. If we ever add paid features, they will be for things that genuinely require a server (like saved workspaces that you explicitly opt into), and the free, private, local tools will remain free.
For a detailed breakdown of what analytics data we do collect (page view counts, no PII), see the Privacy Policy.
Contact
Questions, bug reports, or tool requests — email [email protected].