Guide

How to Format JSON

A step-by-step way to format and validate JSON without changing its values.

Formatting JSON step by step: confirm the input is valid before you reformat it, then check that values did not change.

01Steps

  • Paste the document and run validation first.
  • Choose an indentation width and format the document.
  • Compare large integers and strings against the original.
  • Copy the result only after the validation pass is clean.

02Limitations

This procedure assumes syntactically valid JSON as input and cannot repair invalid documents.

Frequently asked questions

Do I need to validate before formatting?
Yes. Validating first tells you whether a change in the output came from your input or from the formatter.

Sources

  1. RFC 8259: The JavaScript Object Notation (JSON) Data Interchange Format — IETF (accessed 2026-09-01)