What is YAML? What is JSON?
YAML (YAML Ain't Markup Language) is a human-friendly data serialization format that uses indentation instead of braces and brackets. JSON (JavaScript Object Notation) is a lightweight data-interchange format that is easy for machines to parse and generate. Both formats represent structured data as key-value pairs and arrays, but they differ in syntax and readability.
YAML favors human readability: it uses indentation for nesting, supports comments with #, and eliminates the need for quotation marks around most strings. JSON is stricter: every key must be double-quoted, no comments are allowed, and structure is defined entirely by braces {} and brackets [].
Why Convert Between YAML and JSON?
Many tools and platforms accept one format but not the other. Kubernetes manifests, Docker Compose files, and GitHub Actions workflows use YAML. APIs, package manifests (package.json), and configuration endpoints typically use JSON. Converting between them is a daily task for developers working across these ecosystems.
Common scenarios include: transforming a Kubernetes YAML manifest into JSON for an API call, converting an API response into readable YAML for documentation, or migrating configuration between systems that expect different formats.
YAML Syntax Basics
YAML uses indentation (spaces, not tabs) to denote structure. A key-value pair is written as key: value. Lists use a dash prefix: - item. Nested objects are simply indented further. Unlike JSON, YAML allows comments with #, multi-line strings with | (literal) or > (folded), and does not require quotes around most strings.
Common pitfalls include mixing tabs and spaces (YAML requires spaces only), forgetting the space after a colon, and accidentally creating strings that look like booleans (yes, no, true, false are all interpreted as boolean values in YAML).
How to Use This Converter
- Paste your YAML or JSON into the input panel.
- Click Auto Convert to automatically detect the format and convert to the other. Or use the explicit YAML to JSON / JSON to YAML buttons.
- Review the output, then click Copy to copy it to your clipboard.
- The URL updates as you type, so you can share your conversion by copying the address bar.
Frequently Asked Questions
What is YAML?
YAML (YAML Ain't Markup Language) is a human-readable data serialization standard commonly used for configuration files. It uses indentation to represent hierarchy, supports comments, and is designed to be easy to read and write by hand. It is widely used in DevOps tools like Kubernetes, Ansible, Docker Compose, and CI/CD systems.
Can YAML have comments?
Yes. YAML supports single-line comments using the # character. Everything after # on a line is treated as a comment and ignored by parsers. This is one of the key advantages YAML has over JSON, which does not support comments at all.
What's the difference between YAML and JSON?
JSON uses braces, brackets, and double-quoted keys with strict syntax rules. YAML uses indentation for structure, allows comments, does not require quotes around most strings, and supports advanced features like anchors and aliases. JSON is better for machine-to-machine communication; YAML is better for human-edited configuration files.
Why use YAML over JSON?
YAML is preferred when humans need to read and edit files regularly. Its cleaner syntax, support for comments, and lack of excessive punctuation make configuration files more readable. JSON is preferred for APIs and data interchange where strict parsing and broad language support matter more.
Is YAML a superset of JSON?
Technically, since YAML 1.2, valid JSON is also valid YAML. A YAML parser should be able to parse any JSON document. However, YAML has many features that JSON lacks (comments, anchors, multi-line strings), so YAML is not a subset of JSON.
What are common YAML errors?
The most frequent YAML errors are: using tabs instead of spaces for indentation, missing the space after a colon in key-value pairs, incorrect indentation levels, and unquoted strings that are interpreted as other types (e.g., yes becoming a boolean). Always use consistent 2-space indentation and quote ambiguous values.