JSONLint is the classic JSON validator -- paste JSON, click Validate, see if it is valid. It works. It is also a bare-bones tool that has not changed much in years, runs ads, and only validates on button click rather than in real time.

This is a comparison of JSONLint with the JSON Formatter at Ultimate Tools, which validates and formats as you type.

What JSONLint does

JSONLint validates JSON and reports the line and position of the first error. It does basic pretty-printing with indentation. The interface is minimal -- textarea in, result out. It has been useful since 2010 and still serves its core purpose.

Feature comparison

Feature JSONLint Ultimate Tools JSON Formatter

JSON validation Yes Yes

Error location (line/col) Yes Yes

Real-time validation No (button click) Yes

Pretty-print / format Yes Yes

Minify / compact No Yes

Syntax highlighting No Yes

Tree view No Yes

Copy formatted output Manual One-click

Dark mode No Yes

Ads Yes No

Account required No Never

Real-time vs button-click…