Home/ Glossary/ YAML ↔ TOML
Konverter

YAML ↔ TOML

The YAML ↔ TOML Converter translates between YAML and TOML configuration formats in both directions. This tool is useful when migrating a project between toolchains that favor different config formats – for example, converting a YAML GitHub Actions workflow variable file to TOML for use in a Rust project, or converting a Cargo.toml to YAML for an Ansible inventory.

YAML vs TOML – comparison

YAML (YAML Ain't Markup Language) uses indentation-based structure and is the standard format for Kubernetes, Docker Compose, Ansible, GitHub Actions, and many CI/CD systems. It supports comments, anchors, and complex data types but is sensitive to indentation and has type coercion quirks. TOML (Tom's Obvious Minimal Language) uses section-based syntax ([table]) and explicit types, making it less error-prone for simple configuration. TOML is standard for Rust (Cargo.toml) and Python packaging (pyproject.toml). Both formats support comments, but TOML's stricter grammar avoids many of YAML's foot-guns.

How does the converter work?

The conversion route is YAML → parsed data tree → TOML (or TOML → parsed data tree → YAML). The tool uses a YAML 1.2 parser and a TOML serializer/parser. YAML anchors and aliases are resolved during parsing. YAML null values (~) cannot be represented in TOML and are either omitted or reported as incompatible. Mixed-type YAML arrays (e.g. [1, 'two', true]) are invalid in TOML and will produce a conversion warning. YAML multi-line strings are converted to TOML multi-line strings using triple-quote syntax.

Typical Use Cases

  • Converting a YAML Docker Compose environment variable file to TOML for a Rust service
  • Migrating a project configuration from YAML to TOML when adopting a TOML-native toolchain
  • Comparing YAML and TOML syntax for the same configuration to choose a format
  • Generating TOML configuration templates from existing YAML-based documentation

Step-by-step Guide

  1. Step 1: Paste your YAML or TOML content into the input field.
  2. Step 2: Select the conversion direction: YAML → TOML or TOML → YAML.
  3. Step 3: Review the output and any warnings about incompatible values.
  4. Step 4: Copy or download the converted configuration.

Example

Input
database:
  host: localhost
  port: 5432
Output
[database]
host = "localhost"
port = 5432

Tips & Notes

  • Remove YAML null values before converting to TOML, since TOML has no null type.
  • YAML boolean shorthands (yes/no/on/off) are resolved to true/false by the YAML parser before TOML output.
  • TOML array of tables ([[table]]) is the idiomatic way to represent YAML sequences of mappings.

Frequently Asked Questions

Can YAML's null values be represented in TOML?
No. TOML does not have a null type. During YAML-to-TOML conversion, null-valued keys are either omitted with a warning or converted to an empty string, depending on the tool setting.
Are YAML comments preserved in TOML output?
Both YAML and TOML support comments, but comments are not part of the parsed data tree. They are dropped during conversion and cannot be automatically transferred.
What if my YAML has anchors?
YAML anchors and aliases are resolved to their actual values during parsing. The resulting inlined values are then written to TOML without any reference mechanism.
YAML ↔ TOML
Convert YAML to TOML and TOML to YAML — live and bidirectional with full syntax validation.
Open Tool
Similar Tools
TOML ↔ YAML
YAML ↔ JSON
TOML ↔ JSON
JSON ↔ YAML
YAML Formatter