JSON Formatter & Visualizer – Format, Validate & View JSON
Paste messy JSON and get it back clean: pretty-printed with your choice of indentation, checked for errors with the exact line and column pointed out, and laid out as a collapsible tree you can explore key by key. It all runs in your browser — your data is never uploaded.
Developers, data analysts and anyone working with APIs meets raw JSON every day — usually as one unreadable line, or worse, with a hidden syntax error. This formatter beautifies it with 2-space, 4-space or tab indentation, can sort keys A–Z, and can minify it back to one line. The validator does not just say “invalid”: it shows the error and works out the line and column. The tree view turns nested objects and arrays into expandable rows with type labels and counts, so you can understand a payload's shape at a glance, then copy or download the cleaned result.
How to use it
Paste your JSON — type or paste it into the box, or open a .json file from your device.
Choose indentation — 2 spaces, 4 spaces or tabs, and optionally sort keys A–Z.
Format, minify or validate — Format beautifies and validates; Minify compacts; Validate only just checks and reports.
Explore and export — browse the tree view, expanding and collapsing branches, then copy the formatted JSON or download it as a .json file.
What you get
Format & beautify — syntax-highlighted pretty JSON with 2-space, 4-space or tab indentation.
Honest validation — invalid JSON gets the real parser error plus the line and column where it breaks.
Collapsible tree view — objects and arrays expand and collapse, with item counts and type labels.
Useful extras — minify, sort keys A–Z, key/object/array counts and depth stats, copy and .json download.
Frequently asked questions
How do I format JSON online?
Paste your JSON into the box above and press Format / beautify. Valid JSON comes back pretty-printed with your chosen indentation, syntax highlighting and a tree view; invalid JSON returns an error pointing at the line and column that need fixing.
What makes JSON invalid?
The usual causes are a trailing comma after the last item, single quotes instead of double quotes, keys without quotes, or a missing comma, bracket or brace. The validator message and location help you find which one.
Is my JSON uploaded anywhere?
No. Formatting, validation and the tree view all run in your browser with JavaScript — the JSON you paste never leaves your device.
Can I minify JSON or sort its keys?
Yes. Minify removes all optional whitespace for the smallest valid output, and the Sort keys A–Z option reorders every object's keys alphabetically, including nested ones.