The last JSON tool you'll ever need.
Format, validate, minify and visualize JSON as a tree or grid. Query with JSONPath, diff two documents and generate realistic samples — 100% in your browser, no data ever leaves your machine.
- Client-side only
- Zero telemetry
- RFC 8259 compliant
- 5 tools · 1 place
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- Nothing you paste leaves your device.
- Instant validation with line and column errors.
Built by developers who were tired of ad-choked, sketchy formatter sites
DevToolAI started as a personal collection of scripts for formatting JSON payloads while debugging APIs. Most of the "free online JSON formatter" sites we found were slow, buried the actual tool under three screens of pop-ups, or silently uploaded whatever you pasted to a server we had no reason to trust. We wanted something we could point a teammate to without a warning label, so we built our own and kept adding to it.
Every tool on this site runs entirely in your browser using standard JavaScript APIs. There is no backend call that receives your JSON, your Base64 string, or your JWT — the parsing, validation and formatting all happen locally on your machine. The only exceptions are the AI-powered tools under /ai, which explicitly send your prompt to Google's Gemini API to generate a response, and we say so on every one of those pages.
We keep the interface deliberately plain: monospaced labels, keyboard shortcuts, and no dashboards you didn't ask for. If you have a tool you wish existed, or you found a bug in one of the existing ones, the fastest way to reach us is by opening an issue on GitHub.
Common questions
For the standard developer tools — JSON, Base64, JWT, UUID and Hash — no. All parsing and formatting happens in your browser using JavaScript. The only tools that send data anywhere are the AI-powered tools under /ai, which send your prompt to Google's Gemini API to generate a response, and this is disclosed on those pages.
No. There is no sign-up flow and no account system. Every tool works the moment the page loads.
The site is supported by a small amount of display advertising and optional reader tips. There are no paid tiers, so the tools stay the same for everyone.
The core developer tools work offline once the page has finished loading, since they run entirely client-side. The AI tools require an internet connection because they call an external API.
The formatter and validator follow RFC 8259 and report every syntax error it finds in a document, not just the first one, along with the line and column where each error occurs.
Ship faster with AI-powered helpers
Six task-specific tools powered by Google Gemini. Streaming answers, zero setup.
Every dev utility, one keystroke away
Handcrafted, keyboard-first, private by default. Each opens on its own page with a short guide.
JSON Formatter & Validator
Most ImpactBeautify, minify, validate and inspect JSON with a rich Tree Viewer and Grid Viewer.
Base64 Encoder / Decoder
Encode text and files to Base64 or decode Base64 back to text — instantly.
JWT Decoder
Decode and inspect JSON Web Tokens — header, payload, expiry, and claims.
UUID Generator
Generate cryptographically strong UUID v1 / v4 / v7 — single or in bulk.
Hash Generator
MD5, SHA-1, SHA-224, SHA-256, SHA-384, SHA-512 hashes — client-side & safe.
Six reasons developers pick DevToolAI
Every developer tool and AI tool is completely free. No sign-up, no credit card, no usage caps, and no "pro tier" hidden behind a paywall.
JSON, Base64, JWT, UUID and Hash tools run 100% client-side in your browser. Even our AI tools never persist your code on our servers after the response is generated.
Keyboard-first, mono-spaced UI designed to get out of your way. Global search with ⌘K, and every output is copy-paste ready without extra clicks.
Six task-specific AI tools stream answers token-by-token so you never wait on a blank spinner wondering if the request went through.
JSON tools follow RFC 8259 strictly, with multi-error validation that points to the exact line and column where your document breaks.
Source is on GitHub, pricing is predictable (free), and there are no dark patterns. Feature requests and bug reports are always welcome.
Bookmark it. Share it. Save 100 hours a year.
One keyboard shortcut opens the global search. Everything else is one click away.