JSON Formatter & Validator
Paste JSON to validate it, format it with two-space indentation, or minify it. Error messages include the line and column where parsing stopped.
Good to know
- Formats with JSON.parse + JSON.stringify, so 1.0 becomes 1 and duplicate keys collapse; formatted output is re-serialised, not byte-preserved.
Common questions
What does the validator catch?
Syntax errors, with the line and column where JSON.parse stopped. It reports the first error only.
Why did 1.0 become 1 after formatting?
JSON does not distinguish 1 from 1.0. Formatting re-serialises the parsed value, so number formatting and duplicate keys collapse.
Can it handle very large JSON?
Files of a few megabytes work in the tab; much larger documents can be slow on phones with limited memory.
Is this tool really free?
Yes. There is no account, no paywall and no usage limit. Tools App is funded by aumenso, the studio behind it.
Is anything I enter uploaded?
No. The tool runs in your browser tab; what you enter is never sent to us and never stored.
Need this built for your business?
aumenso builds websites, branding, SEO, GoHighLevel funnels and custom software for agencies and businesses across North America and Europe. These tools are the same team's work, given away free.