Question 1

What is the difference between formatting, minifying, and validating JSON?

Accepted Answer

Formatting re-indents JSON for readability without changing its data. Minifying does the opposite — it strips every insignificant space and newline to make the output as small as possible. Validating does neither; it only checks whether the JSON is syntactically correct and tells you where it breaks if not. This page gives you all three as tabs over the same input.

Question 2

Does this formatter support JSON5, JSONC, or trailing commas?

Accepted Answer

No — it parses strict JSON only (RFC 8259), the same rules as JSON.parse. Comments, trailing commas, single-quoted strings, and unquoted keys will all fail validation. If you need to work with JSON5 or JSONC (common in config files like tsconfig.json), strip the comments first.

Question 3

Is there a size limit on how much JSON I can format?

Accepted Answer

It's been benchmarked with a 50MB JSON string and stayed responsive with no dropped frames — inputs over 200KB automatically run in a background Web Worker so the tab never freezes while formatting.

Question 4

Does any of my JSON get sent to a server?

Accepted Answer

No. Parsing and formatting both happen entirely in your browser, in JavaScript — nothing you paste here is ever transmitted anywhere, which also means it keeps working if you go offline.

Question 5

Why do I get a "Line X, Column Y" error instead of just "invalid JSON"?

Accepted Answer

Standard JSON.parse errors are often vague (e.g. "Unexpected token") and don't say where the problem is. This tool locates the exact character offset the parser failed on and converts it to a line and column number, so you can jump straight to the broken bracket, quote, or comma instead of scanning the whole document.

JSON Formatter

Ultra Fast

Local Processing

Syntax Rich

Frequently Asked Questions