JSON Formatter & Validator

JSON (JavaScript Object Notation) is a lightweight, text-based data format for exchanging structured data between applications. It is defined by RFC 8259 and is the default choice for REST APIs, configuration files, log pipelines, and message queues.

JSON supports objects {}, arrays [], strings, numbers, booleans, and null. It is human-readable when formatted and easy for machines to parse with JSON.parse() in JavaScript or equivalent libraries in every major language.

Minified JSON from production APIs is valid but hard to review during debugging. Beautifying (pretty-printing) inserts indentation and line breaks so you can spot missing keys, wrong types, and nested structure at a glance.

• Code reviews and pull requests are faster with readable payloads.
• Diff tools show meaningful line-by-line changes on formatted JSON.
• Documentation and blog posts need consistent 2- or 4-space indent.
• Before committing config to Git, format once so teammates share the same style.

When you are done inspecting, minify again to reduce bytes for storage or transport — our tool handles both directions in one click.

Strict JSON (RFC 8259) requires:

• Double quotes around all object keys and string values — single quotes are not valid.
• No trailing commas after the last element in an object or array.
• No comments (// or /* */) — use our Repair button to strip them if pasted from config files.
• Numbers without leading zeros (except 0.x) and no NaN or Infinity.
• Escape special characters inside strings: \n, \t, \", etc.

Our validator runs the same rules as your browser's JSON.parse() and reports the exact line and column when syntax fails.

Beautify expands JSON with your chosen indent (2 spaces, 4 spaces, or tabs) so nested objects and arrays align visually. Use it when reading API responses, OpenAPI examples, or exported database rows.

Minify removes all unnecessary whitespace and produces a single line — ideal for HTTP bodies where every byte counts, or for embedding JSON inside HTML script tags.

Sort keys recursively orders object keys A→Z at every level, which makes diffs stable when two payloads differ only in key order. Pair it with beautify before committing to version control.

Large documents are easier to explore in a collapsible tree than in a flat textarea. Expand objects and arrays, search keys and values, and copy a path like $.users[0].email to use in documentation, jq filters, or API testing tools.

Switch to Preview mode for syntax-highlighted formatted output — strings, numbers, booleans, and keys use distinct colors so structure pops without running a separate highlighter.

Stats under the editor show character count, total keys, max nesting depth, and type breakdowns (objects, arrays, strings) so you can sanity-check payload size before sending to production.

• Unexpected token — often a missing comma between properties, an extra comma before }, or a single-quoted string.
• Unexpected end of JSON input — truncated copy/paste, unclosed bracket, or cut-off API response.
• Bad control character — raw newlines or tabs inside a string instead of escaped sequences.
• Duplicate keys — valid in some parsers but undefined behavior; last value wins in JSON.parse.

Use Go to line on the error banner to jump straight to the problem row in the editor, then fix and watch the tree update live.

Real-world payloads often include trailing commas from JavaScript object literals or // comments from JSONC config files. Our Repair action safely strips comments (without touching strings) and removes trailing commas, then beautifies if the result parses.

Repair is a best-effort helper — it does not convert single quotes to double quotes or fix unquoted keys. For those cases, fix manually or paste from a source that exports strict JSON.

This formatter runs 100% in your browser. Nothing you paste is uploaded, logged, or sent to our servers. Auto-save uses only your device's localStorage and can be cleared with the Clear button or by wiping site data.

Still treat pasted JSON as sensitive: API responses may contain access tokens, emails, or internal IDs. Avoid sharing formatted output in public tickets or screenshots when the payload is confidential.

For JWT payloads specifically, use our JWT decoder which understands header, signature, and claim semantics.