Validate, clean, and beautifully format raw JSON with real-time syntax checking and error detection.
Formatted JSON will appear here.
What this formatter actually checks, how to open, create, and edit JSON files with no extra software, and answers to the questions we get asked most.
JSON is the standard format for API responses, config files, and data exchange between systems, and it has strict, unforgiving syntax rules — a single missing comma or an unquoted key makes the whole file invalid. This formatter parses every token in your file, checks it against those rules, and reports exactly where it breaks if it does, then re-applies consistent indentation so nested structures are readable at a glance.
A .json file is plain text, so it opens in any text editor — Notepad, TextEdit, VS Code, or a browser tab — with no special software required.
Right-click the file and choose "Open with," then pick any text or code editor; double-clicking it may instead launch whatever app your operating system has associated with .json files, which is sometimes a browser. If you just want to read it comfortably rather than open it in an editor, pasting the contents into the box above and clicking Format & validate gives you indented, color-coded output and a collapsible tree view without installing anything.
Write valid JSON text in any editor and save the file with a .json extension — that's the entire requirement, since JSON has no binary format or special file header.
Start from {} for an object or [] for a
list, add your key-value pairs with double-quoted keys, and save. If
you're not sure the syntax is right, paste it into the formatter above
before saving — it will catch a missing comma or bracket immediately
rather than after your program fails to load the file.
Open the file in a text editor, make your change, and validate the result before saving over the original — JSON's strict syntax means one stray character can break a file that an application depends on.
A code editor with JSON syntax highlighting (like VS Code) catches some mistakes as you type, but it won't catch everything — a duplicate key, for instance, is valid syntax that most editors won't flag even though only the last value survives. Running the edited file through this formatter's validate step, and checking the duplicate-key warning, is a quick safety check before you overwrite a file something else depends on.
JSON is plain text — open, create, or edit a .json file in any browser tab or text editor, no install required.
Syntax errors are reported with the exact line and column, not just a generic "invalid JSON" message.
Parsing and formatting happen entirely in your browser — nothing you paste is ever sent to a server.
{} or [], add double-quoted
keys and values, and validate it in the formatter above before
saving to catch syntax mistakes early.