YAML ↔ TOML Converter

Convert YAML to TOML and TOML to YAML without losing types

YAML and TOML describe the same kind of data — nested keys, lists, strings, numbers, booleans and dates — but tools disagree about which one they read. Hugo, Netlify, Cargo, Poetry and pyproject want TOML; Kubernetes, GitHub Actions, Docker Compose and Helm want YAML. This YAML to TOML converter moves a configuration between the two in either direction, keeps the types intact and shows the JSON it passes through so you can see exactly what was understood.

It is built for the awkward parts: TOML tables become nested YAML maps, YAML lists of maps become [[arrays of tables]] with their sub-tables, date-only, local and offset date-times survive as TOML dates rather than quoted strings, and multi-line YAML block scalars come out as """ strings instead of one long escaped line.

Parsing uses two open-source libraries loaded in your browser — js-yaml 4.1.0 (MIT) for YAML and smol-toml 1.9.1 (BSD-3-Clause) for TOML 1.0 — and the text never leaves your device.

How to use the YAML ↔ TOML Converter

1. Choose the direction: YAML → TOML or TOML → YAML. JSON is valid YAML, so it can be pasted on the YAML side too.
2. Paste the document into the input, drop a .yaml, .yml or .toml file on it, or press Load file — the direction follows the file extension. Sample loads a worked example for the current direction.
3. Read the result on the right; it updates as you type. Any syntax error is reported with its line and column.
4. Adjust the options: indent width for the YAML and JSON output, """ blocks for multi-line strings, dropping of null values (TOML has none) and sorted keys.
5. Open the JSON panel to check how dates, numbers and nesting were interpreted, then Copy result or Download as .toml / .yaml.
6. Press Swap to feed the result back in the other direction and confirm the round trip.

YAML ↔ TOML Converter features

How YAML and TOML values map to each other

Worked example: a Hugo menu

A YAML menu with a list of entries:

menu:
  main:
    - name: Home
      url: /
      weight: 1
    - name: Posts
      url: /posts/
      params: {icon: book}

becomes TOML arrays of tables, one [[menu.main]] per entry, with the inline params map written as a sub-table:

[[menu.main]]
name = "Home"
url = "/"
weight = 1

[[menu.main]]
name = "Posts"
url = "/posts/"

[menu.main.params]
icon = "book"

Things to check after converting

For JSON-specific needs use the YAML ↔ JSON Converter; to tidy the YAML side first, the YAML Formatter reports YAML 1.1/1.2 ambiguities such as unquoted yes and no. The JSON Formatter validates the JSON panel output if you copy it elsewhere.

• Version numbers and IDs: YAML reads 1.10 as the float 1.1 and 0755 as 755 (YAML 1.2 core schema). Quote them in the source if they are strings.
• Dates you meant as text: an unquoted 2026-03-15 becomes a TOML date. Wrap it in quotes to keep a string.
• Comments and key order: comments are gone, and keys keep their original order unless Sort keys is on.
• Large floats and integers beyond 2⁵³ lose precision in JavaScript; check them by eye.