Input — paste anything

⚡ Auto-fixed issues see changes ↓
Ready — paste JSON or any text containing JSON
🌳
Tree view appears here after processing
Click nodes to copy JSONPath • Single-click a leaf to copy value
Formatted output appears here...
Process JSON to generate code...
Insights appear after processing
Shows what JSONBlitz changed to fix your JSON. Process some broken JSON first.
No changes recorded yet.
⌘↵ fix & copy   ⌘⇧V paste & fix   ⌘K actions   click copy value   dblclick copy path © 2026 JSONBlitz

JSONBlitz — Fix Invalid JSON Instantly. Free Online JSON Formatter & Validator 2026.

JSONBlitz is a free, 100% private, client-side JSON formatter, validator, and repair tool. Paste messy JSON, console logs, API responses, or stack traces — JSONBlitz finds the JSON, fixes it automatically, and gives you clean output plus TypeScript interfaces, Zod schemas, and Python TypedDict code. Nothing ever leaves your browser.

How to Fix Invalid JSON Online Free

Paste any broken JSON into JSONBlitz. Common errors like trailing commas, single quotes instead of double quotes, unquoted keys, and JavaScript comments are all fixed automatically in one click. The status bar shows exactly what was repaired.

Fix Trailing Comma JSON Error

Trailing commas in JSON objects and arrays are one of the most common errors when copying JSON from JavaScript code. JSONBlitz removes trailing commas automatically and shows you what changed in the Before/After tab.

Extract JSON from Console Logs and Error Messages

Paste a full console log, stack trace, terminal output, or Slack message that contains JSON. JSONBlitz automatically detects and extracts the JSON portion, even if it is buried in surrounding text. Works with ChatGPT and Claude AI output too.

Free TypeScript Interface Generator from JSON

Paste any JSON and click the TS+Zod tab to instantly generate recursive TypeScript interfaces, Zod validation schemas, and Python TypedDict classes. No signup required. Works completely offline.

100% Private JSON Tool — Safe for API Keys and Production Data

JSONBlitz processes everything locally in your browser — your JSON never leaves your device. No data is transmitted anywhere. Safe for API keys, authentication tokens, credentials, and sensitive production data.

Frequently Asked Questions

How do I fix trailing commas in JSON?
Paste the invalid JSON into JSONBlitz. Trailing commas are removed automatically as part of the silent fix engine.
Is my JSON private and secure?
Yes. Your JSON never leaves your browser — all processing happens locally in JavaScript. No data is transmitted anywhere.
Can it extract JSON from console logs or error messages?
Yes. Paste full logs, stack traces, Slack messages, or AI output. JSONBlitz finds and cleans the JSON automatically.
How does the TypeScript generation work?
Process your JSON and click the TS+Zod tab. JSONBlitz generates recursive TypeScript interfaces and Zod schemas ready to copy into your codebase.
Does JSONBlitz work offline?
Yes. Once loaded, JSONBlitz works completely offline thanks to PWA support and can be installed as a desktop or mobile app.
Is JSONBlitz free?
Yes. The core tool is completely free with no signup and no limits.
How is JSONBlitz different from other JSON tools?
JSONBlitz is built for real-world messy data — logs, errors, buried JSON — with smart auto-repair, instant code generation, and a strict privacy-first approach. Your data never leaves your browser.
Can I share fixed JSON with teammates?
Yes. The Share Link button creates a URL with your JSON encoded directly in it. No server, no storage required.

© 2026 JSONBlitz — jsonblitz.dev — Free JSON formatter — Fix invalid JSON online — JSON repair tool — JSON validator — TypeScript generator from JSON — Zod schema generator

Frequently asked questions

What is JSONBlitz?

A free, privacy-first JSON repair tool. Paste any broken JSON — including AI output, log files, or API responses — and JSONBlitz fixes it instantly in your browser. No data leaves your device.

Is my JSON data private?

Yes. Your JSON never leaves your browser — all processing happens locally in JavaScript. No data is transmitted anywhere. Safe for API keys, credentials, and production data.

What errors does it fix automatically?

Trailing commas, single quotes, unquoted keys, JavaScript comments, Python True/False/None, smart quotes, invalid escape characters, unterminated strings, and truncated JSON. Also extracts JSON from surrounding text.

Can it fix ChatGPT or Claude JSON output?

Yes. LLM-generated JSON commonly includes markdown fences, trailing commas, and missing closing brackets. JSONBlitz strips the fences, repairs the syntax, and shows exactly what changed in the Diff tab.

Does it generate TypeScript and Zod schemas?

Yes. The Types and Schemas tab generates TypeScript interfaces, Zod schemas, Python TypedDict classes, and JSON Schema draft-07 — all ready to copy into your codebase.

How is it different from JSONLint?

JSONLint validates and tells you what is wrong. JSONBlitz repairs automatically and shows a diff of every change. It handles real-world messy inputs — AI output, logs, traces — not just nearly-valid JSON.

Recent Sessions