Frequently Asked Questions
Answers to common questions about JSON Online.
1 Is my data safe?
Absolutely. JSON Online processes everything locally in your browser. No data is ever sent to a server. You can verify this by opening the Network tab in your browser's Developer Tools — you'll see zero outbound requests with your data.
2 Can I use this offline?
Yes! JSON Online is a Progressive Web App (PWA). Install it from the browser's address bar or the install button, and it works offline — perfect for development on the go.
3 What JSON size can it handle?
JSON Online can handle files up to several megabytes. Performance depends on your browser and device, but typical API responses and config files work instantly.
4 What does Auto-Fix repair?
Auto-Fix handles the most common mistakes: trailing commas, single quotes instead of double quotes, unquoted keys, JavaScript comments (// and /* */), BOM characters, and JS-only literals like undefined, NaN, and Infinity.
5 How does timestamp detection work?
In the Tree Viewer, numeric values that look like Unix timestamps (seconds or milliseconds) and ISO 8601 date strings are automatically shown with a human-readable date tooltip. No configuration needed.
6 Is it really free?
Yes, JSON Online is completely free with no hidden fees, no signup, and no ads. It's built for developers who just want a fast, clean JSON tool.
7 Does JSON Online support dark mode?
Yes. JSON Online automatically detects your system color scheme preference. It switches between light and dark mode to match your OS settings, reducing eye strain during late-night debugging sessions.
8 Can I use JSON Online on mobile devices?
Absolutely. JSON Online is fully responsive and works on phones and tablets. The editor and all tools adapt to smaller screens, so you can validate or format JSON on the go.
9 What keyboard shortcuts are available?
You can use Ctrl/Cmd+Shift+F to format JSON, Ctrl/Cmd+Shift+M to minify, and Ctrl/Cmd+C to copy. The Tab key inserts spaces instead of changing focus, making the editor behave like a real code editor.
10 How do I import a JSON file from my computer?
Click the upload icon in the toolbar or drag and drop a .json, .jsonl, .geojson, or .txt file into the editor. The file will be loaded instantly without being uploaded to any server.
11 Can I save multiple JSON documents?
Yes. JSON Online supports tabbed editing, allowing you to work on multiple JSON documents simultaneously. All documents are saved locally in your browser using IndexedDB.
12 What is the difference between the editor and tree viewer?
The editor provides a text-based editing experience with syntax highlighting and code folding. The tree viewer displays JSON as a collapsible tree structure, making it easier to explore deeply nested data and see types at a glance.