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YAML to TOML Converter

Convert YAML to TOML online, for free, right in your browser. This YAML to TOML converter migrates configuration written in .yaml or .yml into TOML's table-based syntax, commonly used by Rust, Python, and modern CLI tools. Nested mappings become TOML tables, and arrays of mappings become array-of-tables.

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Supports .yaml and .yml files, processed entirely on your device

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YAML →JSON
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What to expect

  • Nested objects are written as [section.subsection] tables.
  • Arrays of mappings become [[array-of-tables]] entries.
  • Null values are written as empty strings, since TOML has no native null.

Example

Input (YAML)
site:
  name: Aperture Docs
  version: 1.4.2
  active: true
tags:
  - web
  - cli
  - tools
author:
  name: Jane Doe
  email: jane@example.com
Output (toml)
tags = ["web", "cli", "tools"]

[site]
name = "Aperture Docs"
version = "1.4.2"
active = true

[author]
name = "Jane Doe"
email = "jane@example.com"

When TOML is the better config format

TOML was designed for configuration files that humans edit, and it has become the default in several ecosystems: Cargo.toml for Rust, pyproject.toml for Python packaging, and config files for tools such as Hugo and Netlify. If you are moving a project into one of those ecosystems, converting your existing YAML settings is faster than retyping them.

Unlike YAML, TOML doesn't depend on indentation. Structure comes from explicit [table] headers, which removes a whole class of whitespace mistakes. The trade-off is that deeply nested data can look repetitive, which is why this converter uses dotted headers and arrays of tables to keep the result tidy.

  • Python packaging

    Draft the settings for pyproject.toml from an existing YAML-based tool config.

  • Rust and Cargo

    Move structured settings into a format Cargo and its tooling already understand.

  • Static site generators

    Port a Hugo or similar site configuration between YAML and TOML.

  • Avoiding indentation bugs

    Switch a fragile whitespace-sensitive file to explicit table headers.

How YAML maps to TOML

These are the exact rules this converter applies. Each result below was generated by the tool itself, so it matches what you will see in the output panel.

Top-level values and tables

Plain keys come first, then each nested mapping becomes a [table] section.

YAML
title: App
server:
  port: 8080
TOML
title = "App"

[server]
port = 8080

Deep nesting uses dotted headers

Intermediate tables that hold only other tables are collapsed into a single dotted header.

YAML
a:
  b:
    c: 1
TOML
[a.b]
c = 1

Lists of mappings become arrays of tables

Each item gets its own [[double-bracket]] header, repeated once per entry.

YAML
users:
  - name: ada
  - name: alan
TOML
[[users]]
name = "ada"

[[users]]
name = "alan"

Simple lists stay inline

Lists of scalars are written as inline arrays on one line.

YAML
ports: [80, 443]
regions:
  - eu
  - us
TOML
ports = [80, 443]
regions = ["eu", "us"]

A trickier example: nulls, nested tables and job lists

This deployment-style config mixes nested tables, an inline array, a null certificate and a list of job definitions.

Input (YAML)
title: Deploy config
server:
  host: 0.0.0.0
  ports: [80, 443]
  tls:
    enabled: true
    cert: null
jobs:
  - name: build
    steps: 3
  - name: test
    steps: 5
Output (TOML)
title = "Deploy config"

[server]
host = "0.0.0.0"
ports = [80, 443]

[server.tls]
enabled = true
cert = ""

[[jobs]]
name = "build"
steps = 3

[[jobs]]
name = "test"
steps = 5

TOML has no null type, so the missing certificate is written as an empty string and flagged in the notes. The nested tls table keeps its full dotted path, and each job gets its own array-of-tables entry.

Conversion notes for this example
  • TOML has no null value; null fields were written as empty strings.

Reading the TOML in your code

Python 3.11 and later include a TOML parser in the standard library. Note that the file must be opened in binary mode:

python
import tomllib

with open("config.toml", "rb") as f:
    config = tomllib.load(f)

print(config["server"]["host"])
for job in config["jobs"]:
    print(job["name"], job["steps"])

YAML vs TOML at a glance

TOML trades YAML's flexibility for predictability.

FeatureYAMLTOML
StructureIndentationExplicit [table] headers
Null valuesSupported (null or ~)Not supported
Comments# comment# comment
Dates and timesParsed as strings hereNative date-time type
Typical usePipelines, Kubernetes, CIPackage and tool settings

Things to watch for when converting to TOML

  • TOML has no null, so null fields become empty strings; decide whether to remove those keys instead.
  • The document root must be a table, so a top-level YAML list is wrapped under a single "value" key.
  • YAML comments are not carried over; re-add any explanatory comments in the TOML file by hand.
  • Dates and timestamps are written as quoted strings rather than native TOML date-times.

YAML to TOML Converter FAQ

Does TOML support null values?

No. TOML has no null type, so null fields are written as empty strings and flagged in the conversion notes.

How are nested YAML objects handled?

Nested mappings are converted into dotted TOML table headers, such as [server.database].

Is my configuration file uploaded anywhere?

No. Parsing and conversion both happen locally in your browser.

Why was my null value turned into an empty string?

TOML does not define a null type, so there is no faithful way to express it. The converter writes an empty string and notes the substitution; you may prefer to delete the key altogether.

Will the output work in pyproject.toml or Cargo.toml?

The syntax is valid TOML, but those files expect specific table names such as [project] or [dependencies]. Convert your data, then arrange it under the headers your tool requires.

How are lists of objects written?

Each object in a list becomes its own [[array.of.tables]] block, repeating the header once per item, which is the idiomatic TOML way to represent a list of records.

Is there a difference between .yml and .yaml?

No. ".yml" and ".yaml" are just two file extensions for the exact same format — this converter accepts either one, so a "yml to TOML" conversion and a "yaml to TOML" conversion produce identical results.

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Getting an error? Check your input with theYAML Validator, or tidy it first with theYAML Formatter. You can also browse all YAML converters.