AI JSON Repair Tool
Fix broken LLM JSON: strip markdown fences, trailing commas, single quotes, and more.
Related Tools
Extract and fix JSON from mixed LLM output — handles prose, markdown, and concatenation.
Visually build JSON schemas for AI function calling and structured output.
Validate AI JSON output against a JSON Schema — check types, required fields, enums.
Parse and pretty-print SSE stream chunks from OpenAI and similar APIs.
Generate a structured output prompt from a JSON example or schema.
Learn More
FAQ
- What types of JSON errors does this tool fix?
- The tool fixes: markdown code fences (```json ... ```), trailing commas before closing brackets or braces, single-quoted strings replaced with double quotes, unquoted object keys, missing closing brackets/braces (counted by comparing opens vs closes), and JavaScript-style comments (// line comments and /* block comments */).
- Why do LLMs produce broken JSON?
- Language models generate text token by token without a formal JSON parser. Common mistakes include wrapping output in markdown code blocks, using Python-style single quotes, adding trailing commas, or truncating the output mid-structure if the context window is exhausted.
- What is the difference between AI JSON Repair and AI JSON Fixer?
- JSON Repair applies targeted fixes assuming the input is mostly JSON. JSON Fixer is more aggressive — it first extracts the JSON substring from mixed text (finding the first { or [ and its matching closer) and then applies the same repairs. Use JSON Fixer when the model wrapped JSON in prose.
Automatically repair malformed JSON commonly produced by language models. Handles: stripping markdown code fences (```json...```), removing trailing commas before } or ], replacing single quotes with double quotes, adding quotes to unquoted keys, adding missing closing brackets and braces, and removing JavaScript comments (// and /* */). Each applied fix is listed below the output.