Privacy-first developer tools
Your developer toolkit, simplified.
Fast, privacy-first tools for JSON, JWT, and everyday developer workflows. Everything runs locally in your browser.
See it work
Real input, real output — running right here in your browser.
minified.json
formatted
Done in your browserComputed live by the same code the tools use — nothing is sent anywhere.
Open JSON FormatterPopular tools
The tools most people come for.
JSON Formatter
Pretty-print or minify, with 2-space, 4-space, or tab indentation.
Open toolJSON Validator
Tells you which line and column broke, and why — not just that it's broken.
Open toolJSON Diff
Compares the data, so reordered keys stop showing up as changes.
Open toolJSON → CSV
Flatten nested JSON into something a spreadsheet will open.
Open toolJWT Decoder
Splits the token and pretty-prints every claim, without sending it anywhere first.
Open toolJWT Verifier
Verifies HS256/384/512 with WebCrypto — your secret never leaves the tab.
Open toolSQL Formatter
Indents queries clause by clause for ten SQL dialects, or packs them onto one line.
Open tool
Browse by category
Every tool, grouped by what it works on.
JSON tools
Format, validate, compare and convert JSON.
JSON Formatter · JSON Validator · JSON Tree Viewer · JSON Diff
Browse JSON toolsJWT tools
Decode, verify and generate JSON Web Tokens.
JWT Decoder · JWT Verifier · JWT Expiry Checker · JWT Generator
Browse JWT toolsCode formatters
Beautify and minify SQL, HTML, CSS and JavaScript.
SQL Formatter · HTML Formatter · CSS Formatter · JavaScript Formatter
Browse Code formatters
Why ToolJar
Private by design
Every tool runs as JavaScript in your tab. What you paste is never uploaded or stored.
No sign-up
No account, no email, no paywall. Open a tool and use it.
Precise, not vague
Errors point at the exact line and column, and results update as you type.
Frequently asked questions
- Is it safe to paste production data or a real token?
- Nothing you paste leaves your browser — there is no server to send it to. You can confirm it in your browser’s network panel. A live token pasted anywhere is still worth rotating if it grants real access.
- Do the tools work offline?
- Yes. Once a page has loaded, the tool keeps working without a connection, because all the processing happens in the page itself.
- Is ToolJar free?
- Yes. There are no accounts, subscriptions or usage limits.