Format, validate and minify JSON instantly
Paste JSON to prettify it with clean indentation or minify it to the smallest possible size. Syntax errors are reported with the exact line and column.
How it works
Paste your JSON
Nothing is transmitted — it stays in this tab.
Choose an action
Prettify for readability or minify to save space.
Check for errors
Invalid input is reported with an exact location.
It is processed on your machine
This is the kind of content people are most nervous about pasting into a website. Here nothing is transmitted: your browser reads the input, the tool works on it in the tab, and the result is handed straight back. Close the tab and it is gone.
- Opened from your disk by your browser — not sent anywhere first.
- Held in the tab while the tool works, then dropped.
- Saved to your device by your browser, not by a link to a server.
- Closing the tab clears the working copy completely.
- No account, so nothing is ever attached to an identity.
- No tracking of what you worked on or what was inside the file.
There is no queue and no retention policy to read. Whatever you pasted is released the moment the tab closes. See how your data stays inside the tab for the full picture, or follow the DevTools check to verify your file never leaves.
What people use it for
Reading a response that arrived on one line
Prettifying adds the indentation that makes a nested payload legible.
Checking something before you ship it
A quick pass in the browser is faster than wiring up a build step for a one-off job.
Working on a machine you do not control
Because nothing is transmitted, it is safe to use on a shared or locked-down computer.
Handling data you are not allowed to upload
Customer records, keys and internal names often may not leave the organisation at all. Here they do not.
Formats & limits
What this tool accepts, what it produces, and what it will never ask you for.
- Input
- paste or type JSON
- Output
- Formatted or minified JSON
- Maximum file size
- Set by your device, not by a plan
- Files per run
- Not applicable — nothing is uploaded
- Sign-up required
- None
- Watermark
- Never added
- Works offline
- Yes, once the page has loaded
- Supported browsers
- Any current Chrome, Edge, Firefox or Safari
When something goes wrong
Invalid input stops with a plain message that points at the exact problem, rather than a spinner that never finishes.
The content is not in the shape this tool expects. Check for a missing bracket or an extra character and try again.
Why not an online service
A hosted version of this tool means your input is transmitted to a server you have no relationship with. Removing that step removes the whole category of risk.
A typical upload site
This tool
Questions
Is my JSON sent to a server?
No. Formatting and validation happen entirely in this browser tab. Your data never leaves your device.
What is the difference between prettify and minify?
Prettifying adds indentation and line breaks so the structure is easy to read. Minifying removes all unnecessary whitespace to produce the smallest possible file, which is what you want for production.
Does minifying change my data?
No. Whitespace between tokens carries no meaning in JSON, so the parsed data is identical. Only the formatting changes.
Does it work without an internet connection?
Yes, once the page has loaded. Nothing is fetched while you work, so a dropped connection does not interrupt a run.
Do I need an account or an email address?
No. There is nothing to sign up for, and nothing is ever attached to an identity because no file leaves your device.
Can I use the result commercially?
Yes. Nothing produced here carries a watermark or a licence restriction, and no account is attached to the output.