Your JSON never leaves your browser.
JSON Formatter App is built differently from most online JSON tools. Everything happens on your device. No servers receive your data, no databases store it, no public feeds expose it.
Why this page exists
In November 2025, security researchers at watchTowr Labs disclosed that JSONFormatter.org and CodeBeautify.org had been publicly exposing user-pasted data for years through their "Recent Links" feature. The dataset they captured contained over 80,000 files — including API keys, SSH private keys, cloud credentials, and corporate secrets pasted by users who assumed the tools were private.
That breach was not a hack. It was the design: those tools round-trip your input through a server to generate a shareable link, and the resulting pages were publicly indexable. JSON Formatter App has no such feature, because it has no such server. That is a deliberate choice.
The architecture, in one picture
"100% client-side" is easy to claim and hard to verify. Here is the actual data flow: your browser on one side, no server on the other, and three structural guarantees that make a leak impossible by construction.
Three structural guarantees
- No backend, no API
There is no server that receives your JSON. Formatting, validation, schema checks, jq execution and conversion all run as JavaScript inside your browser tab.
- No upload
The HTTPS request boundary stops at serving the page itself. Your input never crosses the network — you can confirm this in the DevTools Network panel.
- No localStorage persistence
Your JSON lives only in component state for the current session. Close the tab and it is gone. We do not write your input to localStorage, IndexedDB, or any other client store.
Contrast with server-side tools: a tool that offers a "Save / Share link" feature must POST your input to a server and store it under a URL. That is exactly the architecture behind the November 2025 JSONFormatter.org / CodeBeautify leak. We do not have that feature, because we do not have that server.
What we do (and don't do)
No backend, no servers
Every byte of JSON you paste is parsed, formatted, validated, and converted entirely inside your browser tab. There is no API that receives your data — because there is no API at all.
Nothing is saved, ever
We do not store your input, do not generate share links, do not keep history on a server. Close the tab and the data is gone. Unlike tools with public "Recent Links" feeds, your JSON cannot leak because it is never written anywhere.
No tracking cookies
We use a single analytics cookie (Google Analytics) for anonymous traffic stats, and localStorage to remember your theme. We do not fingerprint your content, sell data, or run third-party trackers over your JSON.
HTTPS everywhere
The site is served exclusively over HTTPS with HSTS. What you type into the editor stays inside the encrypted browser session on your device.
Safe for secrets
Because processing is local, you can safely paste API responses, config files, and even JSON containing credentials. Nothing is transmitted. (We still recommend redacting secrets out of habit.)
Open and auditable
The processing logic runs from publicly served, minified JavaScript you can inspect in DevTools. No hidden server roundtrips, no obfuscated data collection.
How to verify this yourself
Do not just take our word for it. Here is what you should see in your browser's DevTools when you format JSON on this site:
Run the same test yourself in four steps:
- Open your browser's DevTools → Network tab.
- Paste a large or sensitive JSON document into the editor.
- Click Format, Validate, Convert — anything. Watch the Network panel: you will see zero requests carrying your JSON. Only the initial page load and static asset fetches.
- Try the same on a tool that saves "Recent Links". You will see a POST with your full payload.
That difference is the entire point of this project.
Ready to format JSON without the risk?
No signup. No upload. Just open and use.
Open the editor