JSON Formatter & Validator (Free Online)
Beautify messy JSON code and validation syntax errors. The essential validation tool for developers.
β¨ Convert
- Real-time syntax validation
- Toggle between Prettify / Minify modes
- Auto-insert sample JSON
- One-click copy result
- Error message display
- Collapsible nodes (in viewer mode)
π‘ Info
**Secure your sensitive data** Do you hesitate to use online tools for JSON containing API keys or customer info? This tool runs purely in your browser; your text is never sent to any server.
**Strict JSON Standard Compliance** Unlike JavaScript objects, JSON keys must be double-quoted ("). This tool catches even these subtle errors precisely.
π Usage
- 1
Paste your JSON text into the left input box.
- 2
It will automatically format (Prettify) or show error messages.
- 3
Click the 'Copy' button to get the clean code.
Overview
This tool is designed for fast, local processing with no server upload. It focuses on clarity and repeatable results.
When to use it
- β’ When you need a quick result without installing software.
- β’ When you must keep files on your device for privacy.
- β’ When you want a predictable output for reuse or sharing.
How it works
Your file is processed in the browser. The workflow is deterministic and optimized for common document patterns.
Best practices
- β’ Start with a small sample to confirm output expectations.
- β’ Keep file names simple to avoid OS-specific edge cases.
- β’ If results look off, try the tool again after a page refresh.
Common mistakes
- β’ Uploading encrypted or corrupted files without preparing them first.
- β’ Assuming a tool will fix formatting issues outside its scope.
- β’ Closing the tab before the download completes.
β οΈ Limits
- β’ Large JSON files (10MB+) may cause browser lag.
- β’ Non-standard JSON with comments (//) may cause parsing errors.
π₯ Inputs & Outputs
Inputs
- JSON Text Input Formats: n/a
Outputs
- Formatted Result Formats: n/a
π Privacy & Security
- β’ All text entered remains within your browser.
π Troubleshooting
I get an 'Unexpected token' error.
Your text contains characters invalid in JSON. Common causes are missing commas or trailing commas.
I can't paste very large data.
This may be due to browser memory limits. For files over 5MB, we recommend using a local editor like VS Code.
The result is all on one line.
Check if 'Minify' mode is on. Click 'Prettify' to apply indentation.
β FAQ
Is this free?
Yes, it is completely free for developers.
Is my code saved?
No, it disappears upon refresh and is never sent to a server.
Does it support YAML?
Currently, we only support JSON.
Is there a dark mode?
We currently provide the default theme only.
What is the indentation standard?
We apply a default 2-space indentation.
Are comments preserved?
Standard JSON does not support comments, so they may be removed or cause errors.