DevToolKit

YAML to TOML Converter

Convert YAML to TOML instantly with automatic anchor and alias resolution, configurable null value handling, and Date-to-ISO conversion. Runs entirely in your browser.

Config Converter

YAML → TOML

Configuration

Null HandlingStrip null keys
Anchor Resolution

YAML anchors (&name) and aliases (*name) are automatically expanded during parsing. The output TOML contains the fully resolved data with no anchor syntax.

YAML Input
TOML Output
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How to Use

The YAML to TOML Converter transforms YAML configuration files into valid TOML 1.0.0 output. It handles anchor resolution, null values, and date conversion automatically.

How to use this tool

  1. Paste YAML: Enter your YAML configuration into the left-hand textarea. Click Load Sample to try a Docker Compose-style example with anchors, dates, and null values.
  2. Configure null handling: TOML has no null type. Toggle between Strip (removes null keys entirely) or Empty String (converts null to "") depending on your application's requirements.
  3. Review output: The converted TOML appears instantly in the right panel. YAML anchors and aliases are fully expanded, and dates are output as ISO 8601 strings.
  4. Copy and use: Click the copy button to grab the TOML for your config.toml, Cargo.toml, pyproject.toml, or other configuration files.

About This Tool

YAML vs TOML: Key Differences

YAML and TOML serve similar purposes as human-readable configuration formats, but they differ in important ways. YAML uses indentation-based nesting and supports features like anchors, aliases, and multi-document streams. TOML uses explicit section headers ([table]) and dot-separated keys, making structure unambiguous without relying on whitespace.

Anchor and Alias Resolution

YAML anchors (&name) and aliases (*name) let you define a block of data once and reference it elsewhere. TOML has no equivalent feature. During conversion, this tool fully expands all anchors and aliases so the resulting TOML contains the complete, duplicated data at each reference point. The merge key (<<:) is also resolved, combining inherited fields with any overrides.

Null Value Handling

YAML supports explicit null values using null, ~, or an empty value. TOML 1.0.0 has no null type. This converter offers two strategies: Strip removes keys with null values entirely from the output, which is appropriate when your application treats a missing key as "no value." Empty String converts null to "", preserving the key's presence when your application needs to distinguish between "not set" and "missing."

Why Use This Tool

When to Migrate from YAML to TOML

TOML is becoming the default configuration format in Rust (Cargo.toml), Python (pyproject.toml), Hugo, and Deno. If you are migrating a project from a YAML-based configuration to one of these ecosystems, this converter handles the structural translation automatically. TOML's explicit syntax eliminates the indentation-related bugs that are common in YAML files, especially in CI/CD pipelines and Kubernetes manifests.

Privacy-First Processing

Configuration files often contain sensitive data like API keys, database credentials, and internal endpoints. This converter runs entirely in your browser using JavaScript. Your YAML content is never sent to any server, making it safe for converting proprietary configuration files, environment variables, and infrastructure-as-code manifests.

FAQ

How does this tool handle YAML anchors and aliases?
YAML anchors (&anchor) and aliases (*anchor) are automatically resolved during parsing. The js-yaml parser expands all references into their full values before conversion, so the resulting TOML contains the complete data without any anchor syntax.
What happens to null values during conversion?
TOML has no native null type. This tool offers two strategies: Strip removes any key with a null value entirely from the output, while Empty String converts null values to empty strings (""). Choose based on whether your application treats missing keys differently from empty values.
Can I convert YAML files with dates?
Yes. YAML date values (like 2024-03-15 or 2024-03-15T10:30:00Z) are parsed as JavaScript Date objects by js-yaml and then converted to ISO 8601 strings in the TOML output, ensuring full compatibility with TOML datetime parsing.
Why does conversion fail with a root array?
TOML requires the root value to be a table (equivalent to a YAML mapping or JSON object). If your YAML document is a top-level array or scalar, wrap it in a named key first. For example, change '- item1' to 'items:\n - item1'.
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