Convert YAML to JSON and JSON to YAML online. Bidirectional conversion with validation.
The YAML ↔ JSON Converter performs bidirectional conversion between YAML and JSON formats using the js-yaml library, with instant validation and detailed error messages. It is the go-to tool for DevOps engineers, backend developers, and cloud practitioners who work with configuration files for Kubernetes, Docker Compose, CI/CD pipelines, and APIs. All conversion runs client-side so sensitive configuration data never leaves your browser.
This tool uses the js-yaml library (loaded from jsDelivr CDN) to parse YAML input into a JavaScript object tree, then serialises that tree to a JSON string using the browser's native JSON.stringify with two-space indentation. The reverse direction parses the JSON string with JSON.parse and serialises the resulting object back to YAML using js-yaml's dump function. Both directions validate the input and surface detailed error messages if the syntax is malformed.
Yes. After the js-yaml library is loaded from the CDN on first visit, all parsing and conversion runs entirely in your browser with no data transmitted to any server. Configuration files often contain sensitive values such as database passwords, API keys, and private hostnames, so the client-side approach is a deliberate privacy-first design decision. You can go offline after the page has loaded and the tool will still work for the current session.
js-yaml supports YAML 1.2 core schema, including nested mappings and sequences, multi-line strings (literal and folded block scalars), anchors and aliases, and most common YAML data types. Limitations include no support for YAML merge keys in all edge cases, and YAML-specific types such as !!python/object tags that have no JSON equivalent are rejected or lose their type information. Multi-document YAML streams (files with multiple --- documents) are not supported - only the first document will be parsed.
YAML has several subtle type inference rules that can produce surprising results: unquoted values like yes, no, on, and off are parsed as booleans in YAML 1.1 (the legacy default used by many tools), and bare numbers in octal notation like 010 may be interpreted as the decimal value 8. js-yaml defaults to YAML 1.2 core schema, which is stricter and less surprising, but if your YAML was written for a YAML 1.1 parser (such as PyYAML or Go's gopkg.in/yaml.v2), you may see type differences in the output.
Command-line tools like yq or scripts using PyYAML offer advanced features such as querying, in-place file editing, and batch processing of multiple files, making them superior for automation pipelines. However, they require installation, environment setup, and command-line knowledge. This browser tool requires nothing beyond a modern browser, produces immediate results with a clean UI, and is the fastest option for one-off conversions and ad-hoc debugging of individual configuration blocks.