YAML to TOML converter

Q: How is a two-step conversion checked?

Your input is converted to JSON first, then to the target format. Each step has its own independent check, and both must pass. The checks of both steps are listed under every result.

Q: Is my data uploaded?

No. Everything runs in your browser, in a background worker. Nothing is sent to a server.

Q: How do I convert YAML to TOML online?

Paste your YAML or open a file on the left (or click Example). The TOML appears on the right as you type, already checked. Copy it, or download it as a file. Nothing is uploaded.

Q: Can the TOML 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.

Convert YAML to TOML 1.0, for example to move a config to Cargo.toml or pyproject.toml.

Converter

Key for non-object input

YAML

Open file

TOML

Waiting for input

What you get

Convert YAML to TOML online, for example to move settings into Cargo.toml or pyproject.toml.
Anchors and merge keys are expanded, and nested maps become [tables].
Checked twice: YAML read strictly, then the TOML parsed back with an independent parser and compared.
Private and free: everything runs in your browser, nothing is uploaded, and there is no sign-up.

How each result is checked

Step 1: Your YAML is parsed strictly as YAML 1.2: duplicate keys and syntax errors are rejected with the line number.
Step 1: The JSON output is parsed back and compared with the parsed YAML, value by value.
Step 2: Your input is parsed with a strict, standards-compliant parser.
Step 2: The TOML output is parsed back with an independent TOML parser.
Step 2: The parsed-back data is compared with your original, value by value. Any difference is reported with its exact path.

What can't convert exactly

Anchors (&), aliases (*) and merge keys (<<) are expanded into full copies, because JSON has no references.
Comments and custom tags such as !Ref are not data, so they are not carried over. You get a warning when this happens.
Several documents separated by --- become one JSON array.
TOML has no null, so null values are left out (with a warning).
A TOML file must be a table, so a top-level array is placed under a key you choose.
Numbers are written by value: 1.0 becomes 1 (a TOML integer) and -0.0 becomes 0. The result names any number whose written form changes.

Questions

How is a two-step conversion checked?

Your input is converted to JSON first, then to the target format. Each step has its own independent check, and both must pass. The checks of both steps are listed under every result.

Is my data uploaded?

No. Everything runs in your browser, in a background worker. Nothing is sent to a server.

How do I convert YAML to TOML online?

Paste your YAML or open a file on the left (or click Example). The TOML appears on the right as you type, already checked. Copy it, or download it as a file. Nothing is uploaded.

Can the TOML 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.