Convert YAML to JSON and JSON to YAML online for free. Bidirectional conversion with syntax validation — perfect for Kubernetes configs, Docker Compose, and API work.
YAML to JSON Converter is a free online tool that translates between YAML (YAML Ain't Markup Language) and JSON (JavaScript Object Notation) formats. YAML is a human-friendly data serialization standard commonly used in configuration files, while JSON is the dominant data interchange format for web APIs. This tool performs bidirectional conversion, allowing you to convert YAML to JSON and JSON to YAML with a single click. It uses the industry-standard js-yaml library for accurate parsing and serialization, handling complex nested structures, arrays, multiline strings, and special YAML features with full fidelity.
Use the YAML to JSON Converter when migrating configuration files between formats, converting API payloads from JSON to YAML for readability, or preparing data for tools that accept only one format. It is especially useful when working with Kubernetes manifests, Docker Compose files, GitHub Actions workflows, or Swagger/OpenAPI specifications that may need to exist in both formats. The tool saves time versus rewriting configurations manually and reduces conversion errors.
DevOps engineers and developers frequently use this converter to transform Kubernetes YAML manifests into JSON for programmatic manipulation, convert CI/CD pipeline configurations between formats, translate Ansible playbooks into JSON for API consumption, convert Swagger specifications from YAML to JSON for compatibility with code generators, prepare configuration data for import into databases that expect JSON, and quickly format data for documentation purposes. It is also handy for learning how YAML structures map to JSON and vice versa.
Essential terms and definitions related to YAML to JSON Converter.
A human-readable data serialization format that uses indentation to represent structure instead of brackets or tags. YAML supports comments (#), complex data types (maps, sequences, scalars), and references (anchors/aliases). It is the standard format for Kubernetes manifests, Docker Compose files, Ansible playbooks, and CI/CD pipeline configurations.
A lightweight data interchange format using key-value pairs and arrays with strict syntax rules: double-quoted keys and strings, no comments, no trailing commas. JSON is the dominant format for REST APIs and web data exchange due to its simplicity and universal language support.
YAML's special notation for multi-line strings. The literal block scalar (|) preserves line breaks exactly as written — ideal for scripts and code. The folded block scalar (>) joins lines with spaces — good for long text paragraphs. Adding a - (e.g., |-) strips trailing newlines. These have no JSON equivalent and are lost during conversion.
No. YAML comments (lines starting with #) are lost during conversion to JSON because JSON does not support comments. If you convert back to YAML, the original comments will not be restored.
The tool processes single YAML documents. If your file contains multiple documents separated by ---, you should convert each document individually. Multi-document YAML is commonly used in Kubernetes manifests.
Basic YAML anchors (&) and aliases (*) are resolved during conversion to JSON. The referenced values are expanded inline in the JSON output, producing a fully self-contained JSON document.
The tool validates the YAML syntax before conversion and displays a clear error message indicating the line and position of the syntax error. This helps you quickly identify and fix issues in your YAML content.
Common errors developers encounter and how to resolve them.
YAMLException: bad indentation of a mapping entry at line X YAML is sensitive to indentation using space characters and does not accept tabs. This error typically occurs when there is a tab-space mix or inconsistent indentation levels. Set your editor to "spaces only" mode and verify that all indentation levels consistently use either 2 or 4 spaces. Use your editor's "show whitespace" feature or grep to find any existing tab characters.
YAMLException: duplicate key "apiVersion" at line X The YAML specification does not allow duplicate keys at the same level. This is commonly encountered in Kubernetes manifest files due to copy-paste errors. Check your YAML file for multiple keys with the same name and either remove the duplicates or rename them.
Special characters in string values corrupted during JSON to YAML conversion Characters like colon (:), hash (#), and exclamation (!) have special meaning in YAML. When string values containing these characters are written without quotes, they can cause parsing errors. After conversion, verify that such values are enclosed in double (") or single ('') quotes. URLs, file paths, and API keys are especially susceptible to this issue.
Multiline string conversion error: |- and > block scalars YAML block scalar notations (|- literal block, > folded block) are converted to plain string values in JSON. The |- notation preserves line breaks, while > converts line breaks to spaces. When converting back from JSON to YAML, these special formats are not automatically restored; you may need to manually add the block scalar notation if needed.