JSON formatter, validator and converter
Format, minify and validate JSON with a precise error position, then convert it to YAML, XML or CSV and check the structure at a glance.
- Line and column error positions
- YAML, XML and CSV output
- Byte and depth statistics
- Nothing is uploaded
Validate, inspect, convert
The validator reports the line and column of the first error, the structure panel counts keys and depth, and the converters reuse the same parsed value so nothing is re-read from text.
Paste JSON
Validation reports the exact line and column of the first error.
Structure
- Keys
- 14
- Max depth
- 4
- Arrays
- 1
- Objects
- 4
- Strings
- 6
- Numbers
- 3
- Minified
- 213 B
- Saving
- 35.8 %
Minified vs formatted
Output
Copy or download — no request leaves this tab.
How it works
Data tools that run in your tab
No uploads, no sign-ups and nothing to wait for: parsing and formatting happen inside this page, so the result appears while you type.
1. Paste the data you already have
A CSV export, a JSON payload, a one-line query. It stays in page state: the same textarea you typed into is what the parser reads.
2. Shape it with explicit options
Delimiter, header row, column filter, indentation, dialect, keyword case. Nothing is guessed silently — every choice is a control you can see and change.
3. Watch the output update as you type
Parsing is debounced so a large paste does not freeze the page, and the preview, the statistics and every export are produced from one parse.
4. Check it before you trust it
Warning rows, token counts and byte savings are shown next to the result, so a broken quote or a lost token is visible instead of silent.
Privacy by architecture
Nothing is uploaded — and you can verify it
Privacy claims are cheap, so this one is falsifiable: the app has no upload code path at all.
No upload endpoint exists
None of these tools has a POST route, a storage bucket or a proxy. Open DevTools → Network while you convert a file: the only requests are the page assets.
Your data stays in memory
Files, queries and column choices live in React state inside the tab and are never persisted. Close the tab and they are gone — nothing survives, because nothing was stored.
Deterministic output, byte for byte
The serialisers are hand-written and never consult the locale or the clock, so the same input produces exactly the same export every time you run it.
Free forever, no account required — the tools are static pages that run entirely on the client.
JSON formatter FAQ
Error positions, statistics, minification and the YAML, XML and CSV conversions.
How does the JSON validator report errors?
It parses with the platform's strict JSON parser and converts the thrown message into a line and column, which is far easier to act on than a raw character offset. The error banner stays visible while you fix it and disappears as soon as the document parses.
What do the JSON statistics count?
Keys (every object property), max depth, arrays, objects, strings, numbers, the minified byte size and the size saved by minifying. Byte sizes are UTF-8 byte counts rather than string lengths, so multi-byte characters are measured correctly.
How do I minify JSON?
Choose the Minify option in the indentation row. Whitespace is removed while the data is preserved exactly — key order is untouched unless you also turn on alphabetical sorting.
How is JSON converted to YAML?
Objects become indentation-based mappings, arrays become block sequences and scalars are quoted only when they would otherwise be ambiguous (a value that looks like a number, a boolean or a reserved word such as yes or null).
How is JSON converted to XML or CSV?
For XML, arrays become repeated <item> elements, keys that are not valid XML names are sanitised and text is entity-escaped. For CSV, an array of objects becomes one row per object using the union of the keys as the header, a single object becomes one row, and nested values are written as compact JSON inside their cell.
Will it reformat very large JSON files?
Yes, with the same caveat as the other tools: a few megabytes is comfortable, and the work happens on the main thread after a short debounce. If a document is too large the tab will feel slow rather than fail, and nothing is ever sent to a server.
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In development