A JSON formatter (also called a JSON beautifier) takes compact or messy JavaScript Object Notation and lays it out so humans can read it. The same parser can minify valid JSON for APIs. This page is a free format JSON online tool: paste, tap Format or Minify, copy the result. It also acts as a JSON validator — if the input is not valid JSON, you get the parse error instead of a pretty print.
When to pretty print JSON
API responses, Next.js configs, and export files from a speed-test dashboard all tend to arrive as one line. Pretty print JSON when you need to find a nested key, compare two payloads, or paste an example into documentation. Minify when you are putting JSON back into a request body and every extra byte is noise.
What this tool does not do
It does not “fix” JSON that is actually JavaScript (unquoted keys, trailing commas). It does not evaluate code. It does not talk to the internet speed test. For other browser utilities see the tools section, including a Base64 encoder and a URL encoder.
Common questions
Does this JSON formatter send my data to a server?
No. Formatting, minifying and validation run in your browser. SpeedMetric does not store the JSON you paste.
What is the difference between format and minify?
Format pretty-prints with indentation so you can read the structure. Minify removes extra whitespace so the payload is smaller for APIs or config files.