JSON Formatter & Validator
Turn a one-line blob of JSON into readable, indented text — or squeeze it back into a single line. Syntax errors are pinned to a line and column, and you're warned before large integers lose digits in the process.
Paste here
Result
Base64 · URL
Decode a JWT
The signature is not verified — that needs the key, and pretending otherwise is worse than not doing it. This only decodes the contents.
Hash
MD5 is not included. Browsers don't offer it, and it should not be used for anything new.
UUID · time
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Passwords
Color conversion
- HEX
- —
- RGB
- —
- HSL
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Contrast ratio (WCAG)
This is how text looks in that pair
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Color palettes
Page details
Tags to paste
Paste code
Result
Only comments and whitespace are removed. Names are left alone — renaming without scope knowledge silently breaks code, and it does not make the code unreadable anyway.
Paste HTML
The pasted code is never executed and never leaves your browser — it is only read.
Result
Units
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Pyeong ↔ square meters
1 pyeong is 400/121 m² (about 3.3058 m²). Type in either box and the other updates.
Apartment exclusive area
Apartment sizes quoted in pyeong in Korea usually mean supply area (exclusive area plus stairs and hallways), so they're larger than the exclusive area converted.
Year · sexagenary cycle
Japanese era (wareki) ↔ Gregorian
Short forms like R1.5.1 or H31 work. In a year when the era changed, enter the full date to get a single answer.
Number to Korean words
Used when writing amounts on contracts and quotes — the number and the words together make tampering harder.
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Korean name romanization
Follows the Revised Romanization of Korean. Sound changes inside a given name aren't reflected, as the standard requires. A passport's English name is hard to change, so if you already use a spelling, keep it.
Enter the name in Hangul.
Naming style
Internationalized domain
See the form a non-ASCII domain is actually registered as (xn--). Uses the browser's own standard conversion.
Regular expression
Result
After replacement
Original
Revised
What changed
YAML support covers the widely used subset — where anchors, tags, or multiple documents appear, this stops and says so rather than misreading them.
Result
Cron expression
Next runs
Computed in this browser's time zone. Server cron usually runs in UTC, so these times can differ from what your server will do.
About this tool
How to use it
- 1 Paste your JSON into the left box. The JSON tab is already open, so it's formatted as you paste.
- 2 Pick an indent: 2 spaces, 4 spaces or Minify (one line).
- 3 Copy the result. If something can't be read, the line and column appear above the output.
Good to know
- The page audit reads HTML you paste — use the Link checker to follow a link
- YAML support covers the widely used syntax only
- JWT decoding unpacks the contents; it does not verify the signature
Frequently asked questions
It says there's an error — where is it?
Look near the line and column shown. The usual culprits are a trailing comma after the last item, single-quoted strings and unquoted keys.
A large number changed after formatting.
JavaScript numbers can't hold integers beyond 2^53 exactly, so the last digits shift. You're warned when that happens — wrap the value in quotes to keep it as a string.
Is the JSON I paste sent to a server?
No. Formatting and validation happen inside this browser.
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