JSON Error Repair

Turn a broken JSON blob into valid, pretty-printed JSON — privately, with no upload.

100% private — your files never leave your device. Every tool on this page runs entirely in your browser. Files are processed locally and are never uploaded to any server, never stored, and never shared.

JSON Error Repair

Paste broken JSON or load a file. The tool finds where it breaks and auto-fixes trailing commas, comments, single quotes, and unquoted keys.

🔧
Click or drop a .json file
Nothing is uploaded

Result

The repaired, formatted JSON appears here.

When to use this

JSON breaks constantly in real workflows: a backend returns a log line with a trailing comma, a config file was written by hand with single quotes, an API sample in docs uses comments, or a teammate pasted JS object syntax into a .json file. Strict JSON.parse rejects all of those. This tool applies the safe, common fixes and tells you exactly where anything remains broken.

Worked example

You paste { name: "test", items: [1, 2,], }. The tool strips the trailing commas, quotes the unquoted keyname, and returns valid JSON with two-space indentation. If something deeper is wrong — say a missing brace — it reports the position so you can fix it by hand instead of guessing.

What it fixes and what it won’t

It auto-handles: line/block comments, trailing commas, single-quoted strings, and unquoted object keys. It will not invent missing data or untangle fundamentally different structures (e.g., a value that should be an array but is an object). Always review the output — auto-fixing changes meaning in edge cases, so treat the result as a strong first pass, not gospel.

FAQ

Is my JSON uploaded? No. Parsing and repair run entirely in your browser tab.

It couldn’t fully repair my file. The remaining error and its position are shown. Open the result, find the position, and fix the structural issue (often a missing quote, brace, or bracket) by hand.

Will it change my data values? No. It only touches syntax (quotes, commas, comments), never the values themselves.

Related tools from our network

A focused set of free calculators and guides across related topics — no account required.