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JSON formatter & beautifier
JSON formatter online—beautify or minify, validate syntax, copy result. Local-first. No signup.
What is a JSON formatter?
What you can do here
JSON beautify: Pretty-print nested objects and arrays with 2- or 4-space indentation.
JSON minify: Collapse whitespace for compact API payloads and config files.
JSON validator: Catch syntax errors before you ship; see parse messages with line hints when available.
Copy and download: Copy formatted JSON or save a .json file in one click.
How to format JSON online
Paste your JSON
Drop minified JSON from an API response, log, or config file.
Choose beautify or minify
Pick indentation and optional key sorting for readable diffs.
Copy the result
When validation passes, copy or download the formatted JSON.
Tips for JSON formatting
- 01
Use double quotes
JSON requires "strings". Single quotes and trailing commas are invalid.
- 02
Watch trailing commas
Objects like {"a":1,} fail validation—remove the last comma.
- 03
Sort keys for diffs
Enable sort keys when comparing two API responses side by side.
- 04
Keep secrets local
Prefer this local-first formatter when JSON includes tokens or PII.
Great for
API debugging
Beautify responses from Network tabs and HAR exports.
Config review
Make package and CI JSON files readable before editing.
Payload prep
Minify fixtures for compact request bodies.
Why use this JSON formatter
Local-first
No upload—JSON stays in the browser session.
Free to use
Unlimited format / beautify / minify with no signup.
Validator included
Know immediately when the document is not valid JSON.
Works with large nests
Handles nested objects and arrays as long as the browser can parse them.
Technical notes
- Engine
- Uses the browser JSON.parse and JSON.stringify APIs for validate + format.
- Indent
- Beautify supports 2-space or 4-space indentation; minify emits a single line.
- Sort keys
- Optional deep alphabetical key sort before stringify for stable diffs.
- Privacy
- All formatting runs client-side—no network upload.
Sources & References
“JSON is a text format that facilitates structured data interchange between all programming languages.”
ECMA-404 — The JSON Data Interchange Syntax: Defines the syntax this JSON validator and formatter accepts and re-emits. json.org/json-en.html
“The JSON.parse() method parses a JSON string, constructing the JavaScript value or object described by the string.”
MDN — JSON.parse(): Used to validate input before beautify or minify. developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/parse
“The JSON.stringify() method converts a JavaScript value to a JSON string.”
MDN — JSON.stringify(): Produces the pretty-printed or minified output you copy from this tool. developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/stringify