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TOML to YAML Converter

Convert TOML configuration to YAML: [tables] become nested maps, [[arrays of tables]] become lists, and values YAML would misread are quoted automatically.

Quick presets

Indent

Start with ---

TOMLOpen file

YAML

Runs in your browser — nothing you enter is uploaded or stored.

ToolFeather · TOML → YAML

Scratchpad auto-saved

Stored in this browser (localStorage)

Step-by-step~40s read

How it works — in four simple steps

No signup and nothing to install — it all runs in your browser.

Add your TOML

Paste it into the left box, press Open file, or drag a .toml file onto it. Sample loads a realistic example.

Set the options

Adjust the options above the boxes — the output updates instantly as you change them.

Check the result

Read the status line: it reports rows, keys and any value that couldn't be represented in YAML.

Copy or download

Copy the YAML or download it as a .yaml file. Nothing was uploaded at any point.

Pro tip

Dates are written as quoted ISO strings so every YAML parser reads them identically.

Features

Document marker

Optionally start the file with --- for tools that expect an explicit YAML document.

Private by design

Parsing and conversion run in your browser with JavaScript — your data is never uploaded, logged or stored.

About the TOML to YAML Converter

TOML and YAML are both human-friendly configuration formats, but they organise nesting differently: TOML uses section headers like [server.tls], YAML uses indentation. The data model underneath is nearly the same — maps, lists, strings, numbers, booleans and dates — so converting TOML to YAML is lossless for almost every real file.

The TOML is parsed with a strict TOML 1.0.0 parser (tables, dotted keys, inline tables, arrays of tables, every string form), then written as block-style YAML with two-space indentation. An array of tables like [[workers]] becomes a YAML sequence of maps under workers:. TOML's date-times are written as quoted ISO strings so every YAML parser reads them back identically — unquoted dates are auto-converted to date objects by some YAML libraries but not others.

TOML comments are not carried across, since parsers don't expose them; re-add any that document important settings. If you're migrating a tool's config, check that the target tool reads the same key names — the converter keeps names exactly, including dashes.

Examples

A Hugo site configuration with nested menu tables, an array of tables and parameters.

TOML input

baseURL = "https://example.org/"
title = "Feather Notes"
paginate = 10

[params]
description = "Small notes on data formats"
showReadingTime = true

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

[[menu.main]]
name = "About"
url = "/about/"
weight = 2

YAML output

baseURL: https://example.org/
title: Feather Notes
paginate: 10
params:
  description: Small notes on data formats
  showReadingTime: true
menu:
  main:
    - name: Blog
      url: /posts/
      weight: 1
    - name: About
      url: /about/
      weight: 2

This output was produced by the converter on this page with the default options — load it with the “Hugo config” preset above and change any option to see the effect.

How TOML maps to YAML

In TOML	Becomes in YAML
`[server]` / `port = 8080`	`server:` / `port: 8080`
`[[workers]]`	`workers:` list of maps
Inline table `{ read = 30 }`	nested map
`started = 2026-10-21T09:30:00Z`	`started: "2026-10-21T09:30:00Z"`
Multi-line `"""…"""`	`\|` block scalar (longer text)
`enabled = true`	`enabled: true`

Things that trip people up

Comments are lost. Neither format's parsers expose comments, so they can't be converted. Copy important ones by hand.
Dates are quoted. That's deliberate: unquoted YAML dates become date objects in PyYAML but strings in many JavaScript parsers. Quoted, they're consistent everywhere.
Float formatting. 3.0 in TOML is the number 3 and is written as 3. If a consumer needs a float, it should parse it as one; YAML itself treats 3 and 3.0 as the same value in most loaders.
Key names with dots. A quoted TOML key like "a.b" = 1 is a single key; it's written as a.b: 1, which YAML also treats as one key.

TOML vs YAML at a glance

Property	TOML	YAML
Specification	TOML 1.0.0 (2021)	YAML 1.2.2 (2021)
File extension	.toml	.yaml / .yml
Media type	application/toml	application/yaml (RFC 9512)
Data types	string, integer (64-bit), float, boolean, date-time, array, table	string, int, float, bool, null, map, sequence (+ dates in many parsers)
Comments	Yes #	Yes #
Nesting	Tables and dotted keys	Unlimited (indentation)

TOML: There is no null in TOML, and the document root must be a table (key/value map), not an array.
YAML: YAML 1.2 is a superset of JSON; YAML 1.1 parsers (still common) also read yes/no/on/off as booleans — the “Norway problem”.

Frequently asked questions

5 answers

Is TOML to YAML conversion lossless?

For the data, yes — tables, arrays, strings, numbers, booleans and dates all have YAML equivalents. Comments and formatting are not kept.

How are [[array of tables]] converted?

Into a YAML list of maps under the table's name, one list entry per [[…]] block.

Why are dates in quotes?

So every YAML parser reads them as the same string. Unquoted, some parsers would turn them into date objects and others wouldn't.

Can I convert YAML back to TOML?

Yes, with YAML to TOML. Values with no TOML equivalent, like null, are reported.

Is my data uploaded anywhere?

No. The TOML is parsed and converted by JavaScript in your browser tab; nothing is sent to a server, so it is safe for internal exports, customer lists and configuration files with secrets.