Free online tool to convert between YAML, JSON, and TOML formats.
YAML, JSON, and TOML are all popular formats used for configuration files and data serialization. JSON is primarily used for web APIs, YAML's high readability makes it common in CI/CD configuration, and TOML is widely used in project configurations like Rust's Cargo.toml.
YAML is an indentation-based, human-readable format that supports comments and is widely used in CI/CD pipeline configurations (GitHub Actions, Docker Compose, etc.). JSON uses curly braces and quotes in a strict format, mainly used for web API data exchange. YAML is a superset of JSON, meaning valid JSON is also valid YAML in most cases.
TOML (Tom's Obvious Minimal Language) is similar to INI files and is widely used in project configuration files like Rust's Cargo.toml, Python's pyproject.toml, and Hugo's config.toml. Its section-based structure is well-suited for writing intuitive and explicit configuration files.
Auto-detection analyzes the first character or syntax patterns of the text. It identifies JSON if it starts with { or [, TOML if it has many = signs, and YAML otherwise. If detection is incorrect, clicking a conversion button will show a parse error message that helps identify the correct format.
This tool uses a lightweight parser running directly in the browser. For YAML: basic key-value, nested objects, arrays, and string/number/boolean/null types. For TOML: basic key-value, [sections], [[array tables]], and inline arrays. Advanced features like anchors, aliases, and multi-line strings are not supported.
JSON (2001) is a lightweight data interchange format derived from JavaScript object notation that became the standard response format for REST APIs. YAML (2001), standing for "YAML Ain't Markup Language," is a configuration language that maximizes readability. TOML (2013), created by GitHub co-founder Tom Preston-Werner as a "clear and minimal" configuration language, is widely used especially in the Rust ecosystem.
JSON is the standard for REST APIs and web services. YAML is preferred for Docker Compose, GitHub Actions, and Kubernetes manifests. TOML is used in Rust projects (Cargo.toml), Python packaging (pyproject.toml), and Hugo sites (config.toml). Choose the appropriate format based on your project ecosystem and team conventions.
All data types are preserved when converting from JSON to YAML. When converting from TOML, section structures are converted to nested objects. Comments (#) are supported in YAML and TOML but are removed when converting to JSON. Date/time types are natively supported in TOML but are handled as strings in JSON.