Data study
The State of Broken JSON
Across 43 repairs since May 23, 2026, 18.6 % of the JSON people pasted was already valid and the most common fault was trailing commas (16.2 % of counted faults).
Counted in the browser after each repair as numbers only: the categories the engine applied, never the text. Updated hourly. A small sample so far (43 of the 500 repairs this study waits for before it is cited).
What breaks JSON, all time
One repair can carry several faults; the counts are faults, not documents. 37 faults counted.
- Trailing commas6 · 16.2 %
- Comments inside JSON5 · 13.5 %
- Python literals (True, False, None)5 · 13.5 %
- BOM, null bytes or invisible characters4 · 10.8 %
- Markdown code fences around the JSON4 · 10.8 %
- Missing commas4 · 10.8 %
- Single or smart quotes3 · 8.1 %
- Unquoted keys2 · 5.4 %
- Truncated output (unclosed strings or brackets)2 · 5.4 %
- Several JSON documents run together1 · 2.7 %
- Malformed numbers1 · 2.7 %
Last 28 days
The same count over the last four weeks, so a new model or tool that breaks JSON in a new way shows up here first.
- Trailing commas6 · 16.2 %
- Comments inside JSON5 · 13.5 %
- Python literals (True, False, None)5 · 13.5 %
- BOM, null bytes or invisible characters4 · 10.8 %
- Markdown code fences around the JSON4 · 10.8 %
- Missing commas4 · 10.8 %
- Single or smart quotes3 · 8.1 %
- Unquoted keys2 · 5.4 %
- Truncated output (unclosed strings or brackets)2 · 5.4 %
- Several JSON documents run together1 · 2.7 %
- Malformed numbers1 · 2.7 %
Repairs per week
The last twelve weeks, Monday to Sunday; the current week is green and still counting.
How the numbers are made
The repair engine runs in the browser. After each run the page sends three fields to the site: whether the result was valid, whether the input was already valid, and the list of repair categories applied. Nothing else leaves the browser; the JSON itself is never sent. The API counts its own repairs the same way. The categories are the engine's fifteen repair stages, from stripping Markdown fences to closing truncated structures.
Because one broken document often carries several faults, the category chart counts faults, not documents. “Already valid” means the pasted text parsed before any repair; people paste valid JSON to format or inspect it.
Use the data
Cite the page with a link; the numbers are CC BY 4.0. The raw aggregates are at /api/stats as JSON. For the faults themselves, each has a guide under JSON errors, and the repair itself is one paste away.
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