jsondevv1.0
input.json

Drop a .json, .yaml or .txt file here

or start typing — everything is parsed in your browser

⌘⇧F format⌘⇧M minify⌘⇧S sort⌘⇧E repair

Formatted output, the tree explorer and conversions appear here.

Waiting for inputPaste, drop, or load JSON to validate
No input0 B0 lines— keysProcessed locally

Online JSON formatter, validator & auto-repair tool

JsonDev is a free, fast JSON studio for developers. Beautify or minify JSON, validate it with exact error locations, repair broken or AI-generated JSON automatically, explore it as a tree, and convert it to YAML, CSV or XML. It runs entirely in your browser — no sign-up, no uploads.

Features

  • JSON formatter & beautifier

    Pretty-print JSON with 2 spaces, 4 spaces or tabs. Numbers keep their exact digits, so 64-bit IDs never lose precision.

  • JSON validator

    Validates as you type and lists every syntax error with its exact line and column — click an error to jump straight to it.

  • Auto-repair broken JSON

    Fixes trailing commas, single quotes, unquoted keys, comments, missing brackets, Python True/False/None and JSON pasted from ChatGPT or other AI tools.

  • JSON tree viewer

    Explore large documents as a collapsible tree, filter keys and values, and copy the path of any node, like store.books[0].title.

  • Convert JSON to YAML, CSV & XML

    Turn JSON into YAML, a CSV spreadsheet or well-formed XML in one click. Upload a .yaml file to convert YAML to JSON.

  • Minify JSON

    Compress JSON to a single line for APIs, configs and payloads — whitespace is removed, nothing else changes.

  • Sort JSON keys

    Sort object keys alphabetically at every level to make diffs and reviews easier. Array order is preserved.

  • Private by design

    Everything runs in your browser. Your JSON is never uploaded to a server, so it's safe for tokens, logs and customer data.

How to format and validate JSON

  1. 1Paste JSON, drop a .json or .yaml file onto the editor, or load it from a URL.
  2. 2Read the diagnostics panel — every error shows its line and column. Press Auto-Repair to fix them all.
  3. 3Format, minify or sort keys, explore the tree, or convert to YAML, CSV or XML.
  4. 4Copy the output or download it. Your session is saved in this browser automatically.

Frequently asked questions

›Is my JSON sent to a server?

No. JsonDev parses, validates, formats and converts JSON entirely in your browser. Nothing you paste or upload leaves your device. The only network request involving your data is when you choose to load JSON from a URL.

›How do I fix invalid JSON?

Paste it into the editor. Every problem is listed in the diagnostics panel with its line and column. Click Auto-Repair (or press Ctrl/⌘ + Shift + E) to fix trailing commas, single quotes, unquoted keys, comments, missing brackets and similar issues in one step. Repair can be undone.

›Can it fix JSON generated by ChatGPT or other AI tools?

Yes. Auto-Repair strips markdown code fences and surrounding text, converts Python literals like True, False and None, and closes truncated objects and arrays — the most common problems in AI-generated JSON.

›How large a JSON file can I open?

Files up to 256 MB. Documents over 1 MB are processed in a background thread so the editor stays responsive, and very large documents ask before building the tree view.

›How do I convert JSON to CSV, YAML or XML?

Load valid JSON, then choose CSV, YAML or XML in the toolbar. Arrays of objects become CSV rows with nested fields flattened into columns like address.city. Copy the result or download it with the correct file extension.

›Does it work offline?

Once the page has loaded, formatting, validation, repair, the tree view and the converters all work without a network connection.