UsefulTab

TOML Converter

Convert TOML to JSON, JSON to TOML, or TOML to YAML.

Runs locally in your browser Report an issue
Output

Paste TOML or JSON to convert it

Choose a direction — TOML to JSON, JSON to TOML, or TOML to YAML — and the input is validated first, then converted. It all runs in your browser.

Runs entirely in your browser

Convert TOML to JSON, JSON, or YAML, locally

Paste TOML and convert it to JSON or YAML, or paste JSON and turn it back into TOML. Pick the direction and the input is parsed and validated first, so a syntax error is reported clearly instead of producing broken output. The TOML engine is written from scratch with no dependencies and covers the parts you actually meet in config files: tables like [server], arrays of tables like [[servers]], inline tables, arrays, quoted and literal strings, integers in decimal/hex/octal/binary, floats, booleans, and datetimes kept as strings. YAML output uses a well-known YAML library loaded in your browser. Everything runs on your device, so a config that holds hostnames, keys, or internal settings is never uploaded.

Common questions

Which directions are supported?

Three: TOML → JSON, JSON → TOML, and TOML → YAML. Pick the one you need with the direction buttons. TOML → JSON and JSON → TOML round-trip the same data structure.

Which TOML features does it handle?

A pragmatic subset covering real config files: tables ([a.b]), arrays of tables ([[x]]), inline tables ({ x = 1 }), arrays (including nested and multi-line), basic and literal strings, integers in decimal, hex, octal, and binary, floats (including inf and nan), booleans, and datetimes. Datetimes are preserved as strings rather than Date objects.

Why is a datetime shown as a string in JSON?

JSON has no datetime type, so a TOML datetime like 1979-05-27T07:32:00Z is carried through as a string. This keeps the value intact and lossless when you convert back.

What happens with input it cannot parse?

The converter validates the input first. If the TOML or JSON cannot be parsed, it shows a clear error — including a line number for TOML — instead of emitting partial or broken output.

Is my data uploaded anywhere?

No. TOML and JSON are parsed and converted entirely in your browser tab, and the YAML library is loaded and run on your device too. Nothing is sent to a server, so it works offline and your config stays private.