Online JSON formatter: beautify, minify, validate JSON with one click. Convert to TypeScript/Go/Java. Unicode-safe, supports Chinese and Emoji.
TL;DR: Free online JSON formatter to beautify, minify, and validate. One-click convert to TypeScript, Go, and Java. Unicode-safe with full Chinese and Emoji support, runs locally.
For local tools, open DevTools → Network and search your input — it should not appear in requests.
Next steps
Usage Guide
Formatting turns a minified machine-friendly JSON payload back into an indented, human-readable structure — the first step of debugging API responses and reviewing config files. Everything here runs locally in your browser; your input never touches a server.
1. Format in three steps
Multi-line input and arbitrary whitespace are fine; trailing newlines are ignored. Key order is preserved — use "Sort Keys" when you need alphabetical ordering.
- Paste your JSON into the left editor (straight from an API response, a log, or a config file).
- Hit "Format" — the right side instantly renders a standard 2-space indented structure; syntax errors appear below the buttons with the offending position.
- Copy the result from the output toolbar, or download it as a .json file.
2. Understanding validation errors
"Validate" checks syntax without reformatting and reports the line and position of the first error. In practice 90% of failures fall into three buckets:
- Trailing commas after the last key or array element (legal in JavaScript objects, illegal in JSON).
- Quote errors: single quotes or unclosed strings — JSON only accepts double quotes.
- Smart quotes pasted from docs or chat apps ("") — replace them with straight quotes.
3. One-click type generation
The "TypeScript", "Go" and "Java" buttons translate the current JSON structure into types: objects become interfaces/structs/classes, arrays infer their element type from the first item. Handy when modelling from a sample API response — review nested array types manually afterwards.
4. Power tips
- "Minify" collapses the structure back to one line for smaller configs or CLI arguments.
- Chinese and Emoji survive the round-trip — no \uXXXX escaping appears in output.
- Validate first when inspecting API payloads; formatting is a separate step.
- Your input persists in local storage across refreshes; the clear button wipes it immediately.
5. JSON syntax in five minutes
JSON has exactly six value types: object, array, string, number, boolean and null. Three rules earn memorizing. First, keys must be double-quoted strings — single quotes and bare identifiers are the number-one parse error when pasting from JavaScript object literals. Second, string escapes are limited to \" \\ \/ \b \f \n \r \t \uXXXX; a literal backslash must double. Third, numbers have no octal, no leading zeros, no NaN/Infinity. The subtle trap is precision: most implementations parse JSON numbers as IEEE 754 doubles, silently corrupting integers beyond 2^53-1 — passing IDs as strings is the industry-wide workaround.
6. The follow-up chain after formatting
- Chain into jq: once formatting confirms valid syntax, jq '.data.items[0].id' extracts values in one line — far faster than eyeballing.
- Key-path extraction: the JSON toolkit on this site extracts every key path in one click; reuse the output for config maps or JSONPath authoring.
- Cross-format conversion caveats: YAML multi-documents (---) and anchors have no JSON equivalent, and TOML dates degrade to strings.
- Type generation: only feed format-verified JSON into TypeScript type generators; a syntax error skews the entire inference result.
FAQ
Yes. The TypeScript, Go, and Java buttons translate the current JSON structure into an interface, struct, or class; for arrays, element types are inferred from the first item. Output is structure inference, so review nested array types by hand when you need tighter definitions.
Not here. Most JSON implementations parse numbers as IEEE 754 doubles, so integers above 2^53-1 silently lose precision — the reason passing IDs as strings is the industry convention. This tool's parser is lossless: even huge integers are preserved exactly as written.
Roughly nine out of ten errors fall into three buckets: trailing commas (allowed in JavaScript object literals, forbidden in JSON), single or unclosed quotes (JSON accepts only double quotes), and full-width quotes (“”) copied from documents or chat logs. Error messages carry the line number and position, so you can fix them one by one.
No — processing is Unicode-safe throughout. Formatting also preserves the original key order instead of re-sorting keys alphabetically.
Neither. The page works as soon as it opens: formatting, minifying, and validating all run inside your browser, with no usage caps and no personal information collected.
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