JSON Formatter
Pretty-print messy JSON, validate it, or minify it for production — with clear error messages when it is broken.
What is this tool?
JSON is the language of modern APIs, config files and data exports, but the raw output from a server is often one unreadable line — or worse, subtly broken. This JSON formatter validates your data and reprints it with clean indentation so you can actually read the structure, spot the missing comma, and confirm exactly what an API returned.
Choose two-space indentation (the most common style in US software teams) or four spaces, or minify valid JSON down to a single compact line for production use. Validation error messages point to the problem so you can fix it fast. Everything parses locally in your browser, which makes the tool safe for API responses and config files you would not paste into a random server.
How to use it
- Paste your JSON into the box.
- Click Format to pretty-print it, Validate to only check it, or Minify to compress it.
- Read the status message — errors describe exactly what is wrong.
Formula & method
Worked example
A one-line API response like {"name":"Ada","skills":["math","code"]} becomes a readable, indented document where the nested array is obvious at a glance — and a trailing comma, the most common JSON mistake, is flagged immediately.
Frequently asked questions
Why does my JSON fail validation?
The usual culprits are trailing commas, single quotes instead of double quotes, unquoted keys, or comments — strict JSON allows none of them. The error message here will name the issue.
What is the difference between formatting and validating?
Validating only checks that the JSON is legal and leaves it untouched. Formatting also rewrites it with consistent indentation so it is easy to read and diff.
Is it safe to paste API keys or private data?
The formatter never sends your text anywhere — parsing happens in your browser. Still, good practice is to redact secrets before pasting data into any tool.