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Convert JSON to TOML

Paste your JSON and this tool converts it to TOML instantly, right in your browser. JSON (JavaScript Object Notation) is the lingua franca of web APIs: compact, strictly typed, and supported everywhere. TOML is a configuration format with clear sections and types, used by Cargo, pyproject.toml, Hugo and many tools.

The conversion is completely client-side: there's no upload, no queue, and no account. Big files are converted in the background with a Cancel button, the options for the lossy steps are one click away, and your last conversion is remembered.

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JSON to TOML Converter — frequently asked questions

How do I convert JSON to TOML?
Paste your JSON, or open or drop a file, and the TOML appears instantly. Copy it, download it (named after your file), or open it in another tool. Errors point to the line and column. Everything happens in your browser.
What doesn't fit in TOML?
TOML needs a table at the top, so a list is placed under "items", and it has no null, so null values are left out (the converter says so). Dates and big integers come through exactly.
Is my data uploaded to a server?
No. The conversion runs entirely in your browser — your data never leaves your device, so it's safe to convert configuration, API payloads, and other sensitive files. You can even go offline once the page has loaded.
Is this converter really free?
Yes. No sign-up, no payment details, no file-size paywall, and no watermark on the output.

All format converters

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