JSON
JSON (JavaScript Object Notation) is a text format for objects, arrays, strings, numbers, booleans, and null. It is defined by ECMA-404 / RFC 8259. It is not JavaScript, even though the syntax looks related.
Common uses
- HTTP APIs and configuration files
- Browser storage and structured logs
- Interchange between languages that all have a JSON library
Strengths
- Parsers exist everywhere
- Maps cleanly onto objects and arrays
- Diffable in version control when pretty-printed
Weaknesses
- No comments in the standard
- No date type; people invent ISO strings
- Numbers are often IEEE floats in practice
- Trailing commas are invalid
Compatibility. Any modern language. UTF-8 is the interoperable encoding. UTF-16 and UTF-32 exist in the spec but are a bad idea on the wire.
Size and quality. Verbose compared with binary. Minify for embedding; compress on the wire with gzip or Brotli.
How to open it. Open it in any text editor. Format it with the JSON formatter if it arrived as one line.
How to convert it. Use JSON to YAML, JSON to CSV, JSON to XML, JSON to TOML, or JSON to .env depending on the target. CSV conversion needs an array of objects.
Security and privacy. JSON is data. The danger is executing it as JavaScript, interpolating it into HTML, or logging secrets. ConvertPass never evals JSON.
Related tools
- JSON formatter
Pretty-print JSON locally with clear parse errors and a one-click copy.
- JSON validator
Check whether text is valid JSON, with a useful error location.
- JSON to YAML
Turn JSON into readable YAML without leaving your machine.
- JSON to CSV
Turn a JSON array into CSV without dropping nested values on the floor.
Related comparisons
Last reviewed 16 August 2026.