Repair broken JSON instantly
Paste messy output from ChatGPT, Claude, Gemini or n8n and get clean, valid JSON back in under a second — with a plain-English explanation of every fix.
Free · No signup · Everything runs in your browser
```json
{
"user": {
"name": "Alice",
"active": True,
"score": 98,
"tags": ["admin", "editor",],
// user joined last month
}
}
```Your repaired JSON will appear here, with a clear report of every fix.
Need more than repair? Open the full JSON Studio for format, validate, tree, diff and convert.
One toolkit
Everything you need to work with JSON
Built for the JSON that AI tools actually produce
LLMs wrap JSON in markdown, leave trailing commas, use Python True/False, and cut off mid-stream. We fix all of it automatically.
```json
{
'user': "Alice",
active: True,
"tags": [1, 2,],
}{
"user": "Alice",
"active": true,
"tags": [1, 2]
}Three steps
From broken to valid in seconds
Paste your JSON
Drop a file or paste raw output from any AI tool, API, or workflow. No account, no upload.
We repair it
A 16-stage engine fixes fences, commas, quotes, Python literals, truncation and more — locally in your browser.
Copy the result
Get valid, formatted JSON plus a clear report of every change. Copy or download in one click.
In short
A JSON fixer repairs invalid JSON so it parses correctly. AI JSONMedic takes broken output from ChatGPT, Claude, Gemini or n8n — markdown code fences, trailing commas, single quotes, Python True/False, comments, and truncated responses — and returns valid, formatted JSON in under a second, entirely in your browser, with a plain-English explanation of each change. Free, no signup.
Why You Need a JSON Fixer for AI Output
Large language models like ChatGPT, Claude, and Gemini frequently generate invalid JSON that breaks your applications. Whether you need to fix JSON online from an API response or repair JSON from a chatbot, the problem is the same: AI models produce output that looks right but fails standard JSON parsers.
Common issues include markdown code fences (```json), Python-style booleans (True/False), trailing commas, and truncated responses from streaming APIs. A standard JSON validator only tells you it's broken — our JSON fixer actually repairs it.
Streaming responses create another class of problems: when an LLM hits its token limit mid-response, the JSON is simply cut off — leaving unclosed brackets, arrays, and strings. You need a JSON repair tool that understands these AI-specific failure patterns.
How Our Online JSON Fixer Works
AI JSONMedic is the most advanced JSON fixer online. Unlike generic validators, it understands AI-specific error patterns and repairs them automatically in a 16-stage pipeline:
- Strip markdown code fences and prose prefixes
- Remove encoding artifacts (BOM, null bytes, zero-width characters)
- Straighten smart / curly quotes (“ ” ‘ ’)
- Strip JavaScript and Python comments
- Merge concatenated & NDJSON values into a single array
- Convert Python-style booleans (True/False/None)
- Replace invalid values (NaN, Infinity, undefined)
- Normalize invalid numbers (hex
0x1F, leading+, malformed decimals) - Convert single-quoted strings to double-quoted
- Quote unquoted object keys
- Remove trailing commas
- Insert missing commas between values
- Repair truncated/incomplete JSON structures
- Validate, with a fallback repair pass for anything remaining
- Format the result
- Detect duplicate keys (warning)
Every stage tracks exactly what it changed, so you always get a complete repair report — not a black box.
Who Uses This JSON Fixer
Thousands of developers use AI JSONMedic to fix JSON online every day — from backend engineers integrating LLM APIs, to automation builders fixing JSON in n8n and Make.com workflows, to data engineers repairing JSON from AI pipeline output. If you've ever pasted ChatGPT output into your code and got a parse error, this JSON repair tool is built for you.