TOML to JSON converter
Convert TOML to JSON: Cargo.toml, pyproject.toml or any TOML 1.0 file becomes JSON, with dates and times as ISO 8601 strings and errors reported with their line.
Waiting for input
What you get
- Convert TOML to JSON for any TOML 1.0 file: Cargo.toml to JSON, pyproject.toml to JSON, or app config.
- Dates and times become ISO 8601 strings, and big integers are flagged before JavaScript can round them.
- Strict TOML 1.0 parsing: duplicate keys and redefined tables are reported with their line.
- Private and free: everything runs in your browser, nothing is uploaded, and there is no sign-up.
How each result is checked
- Your TOML is parsed with a TOML 1.0 parser; errors show the line number.
- The JSON is parsed back and compared with the parsed TOML, value by value.
What can't convert exactly
- JSON has no date type, so TOML dates become ISO strings.
- Comments are not carried over.
Questions
Can I convert Cargo.toml or pyproject.toml?
Yes. Paste the file as it is.
How do I convert TOML to JSON online?
Paste your TOML or open a file on the left (or click Example). The JSON appears on the right as you type, already checked. Copy it, or download it as a file. Nothing is uploaded.
Can the JSON output be wrong?
Every result is checked before it is shown (the checks are listed on this page). If a check fails, the page says "Review needed" and why, instead of presenting the output as correct, and anything that cannot convert exactly is named in the notes.