JSON Viewer — Format & Explore JSON Files Online, Free
Open a .json file and explore it as a collapsible tree or pretty-printed raw text — validated and formatted entirely in-browser.
1. Choose or drop a file
2. View instantly
3. Download when done
What this viewer does
- Collapsible tree view for nested objects/arrays
- Pretty-printed raw text view with syntax highlighting
- Instant validation with clear error location on invalid JSON
- Search keys and values
- Copy any node or the whole document
How it's rendered
Custom tree renderer. Parsed with the browser's native JSON parser; rendered as a virtualized collapsible tree.
Nothing about this file is ever sent to a server — open your browser's DevTools Network tab while using this viewer and you'll see no request carrying your file's contents.
100% Private
Files never leave your device. There is no server that ever receives your file's contents.
No Uploads
Every format is decoded and rendered locally via WebAssembly or JavaScript. Open your browser's Network tab and confirm nothing is sent.
No Storage
Nothing is written to a server or database. Memory clears the moment you close or reload the tab.
GDPR-friendly by design
There's no file data collection to comply with in the first place — no account, no tracking of file contents, no analytics on what you view.
JSON viewer — FAQ
Can it handle large JSON files?
Yes, large files render efficiently with a virtualized tree; extremely large files are bounded by device memory.
Will it tell me if my JSON is invalid?
Yes, invalid JSON is flagged immediately with the line and character position of the error.
Can I search inside the JSON?
Yes, the search box highlights matching keys and values in the tree.
Is this the same tool as your JSON formatter?
It shares the same battle-tested parsing/formatting logic as realonlinejsonformatter.com, adapted for file viewing.
Is the file uploaded anywhere?
No, parsing and formatting happen entirely client-side.