JSON Repair - Turn Messy Drafts into RFC 8259 JSON

Input - invalid draft

{a:1,}

Output - RFC 8259 JSON, pretty-printed

{
  "a": 1
}

Salvaging a JavaScript object literal from a console.log

DevTools often prints objects with unquoted keys. Copying that dump into a formatter fails. Paste it here first. If the dump included functions or undefined, repair may still fail or drop those slots - read the output and do not treat a console object as a serialization format.

Fixing trailing commas from hand-edited config

People edit settings.json-shaped files as if they were JavaScript. The last property keeps a comma because the next line might arrive tomorrow. RFC 8259 forbids that comma. Repair removes it. If your toolchain actually wants JSONC (VS Code settings), comments will disappear here; use a JSONC-aware path instead of converting.

Converting single-quoted strings from mixed language dumps

Python repr, some logs, and copy-pasted snippets use single quotes. JSON does not. The heuristic often rewrites them to double quotes. Nested quotes inside strings are the usual footgun - confirm the pretty print still has the same characters you care about.

Closing truncated model or log output (with limits)

Language models and log shippers cut JSON at a byte limit. jsonrepair sometimes closes open braces. That can invent an incomplete object that parses but is missing the tail of the data. Use it to unblock a parser, then treat the result as damaged until you have the full payload. Do not load a 40 MB truncated log into this textarea.

Cleaning concatenated objects from log lines

Two objects stuck together {a:1}{b:2} are not one JSON value. Repair may wrap or join them. If you needed NDJSON, split on newlines yourself. This page is one document in, one document out.

Recovering a draft so a formatter will accept it

The JSON formatter must refuse invalid input or it would silently invent structure. Repair is the step before format. After you agree with the object, format or minify on that page. Keep the jobs separate so you can see what the heuristic changed.

Turning Python True / None dumps into JSON literals

Naive Python prints use True, False, and None. JSON wants lowercase true / false / null. Many drafts convert. Nested Python datetime objects will not. Prefer json.dumps at the source when you control the exporter.

Preparing a broken vendor export for schema validation

Vendor “JSON” is often JSON5-ish. Schema validators expect RFC 8259. Repair, read, then validate on the JSON Schema validator. If validation fails on types, that is a data problem, not a quote problem. Diff the repaired file against a known-good fixture on JSON compare.

What kinds of malformed JSON can be repaired?

Typical draft mistakes: unquoted keys, trailing commas, single quotes, comments, concatenated objects, and Python-style True/False/None in many cases. The default {a:1,} becomes {"a":1}.

Is repaired JSON always what I meant?

No. Repair is heuristic. A missing comma might join two values. Always read the pretty-printed output. Schema validation is a separate step on the JSON Schema validator.

Does JSON repair replace the JSON formatter?

No. The formatter pretty-prints valid JSON and must refuse invalid input. Repair exists because formatters cannot guess quotes and commas. Pretty-print after repair on the JSON formatter if you want a chosen indent.

Is my broken file uploaded?

No. jsonrepair runs entirely in the browser. The draft is stored in localStorage on this device for up to 30 days and is never sent to a server.

Can jsonrepair fix truncated files?

Sometimes it closes open brackets. A file cut in the middle of a string may still fail. Use the JSON file processor only for valid large files, not as a second repair pass.

When should I use JSON5 instead of repair?

JSON5 is a defined dialect that allows comments and unquoted keys on purpose. If you want to keep that dialect, validate it on the JSON5 validator instead of converting it to strict JSON.

What happens if JSON.parse still fails after repair?

The page shows the first parse error with a line and column, and may still display the heuristic text. That means the library could not produce RFC 8259 JSON. Simplify the draft or fix the remaining syntax by hand.

Does repair keep comments?

No. Strict JSON has no comments. Repair strips or rewrites comment-like text so JSON.parse can succeed. If comments must survive, you are writing JSON5 or JSONC, not JSON.

Can I repair NDJSON (one value per line)?

Not reliably. Newline-delimited JSON is many documents, not one. This tool may wrap or merge lines incorrectly. Split lines yourself, repair each value, then join them again.

Is this JSON repair tool free?

Yes. There is no registration, no repair quota, and no premium auto-fix. Run jsonrepair as often as you need on drafts that fit in the textarea.