YAML/JSON Converter
Convert between YAML and JSON formats
Free Online YAML to JSON and JSON to YAML Converter
YAML vs JSON: key differences and when to use each format
YAML (YAML Ain't Markup Language) is a data serialization format designed specifically to be readable by humans. The main differences from JSON are that YAML uses indentation instead of braces and brackets, supports # comments, offers cleaner syntax for complex structures, allows multiline strings without escaping, and supports anchors for reusing data. JSON is preferred for data interchange between systems, REST APIs and any case where fast parsing matters. YAML is ideal for configuration files such as Docker Compose, Kubernetes manifests, Ansible playbooks, GitHub Actions workflows and CI/CD pipelines.
Which YAML features does JSON not support?
YAML offers advanced capabilities that JSON lacks: # comments for documenting configuration, anchors (&name) and aliases (*name) for reusing blocks of data without duplication, native support for multiple documents in a single file separated by ---, multiline strings with | (literal) or > (folded) that need no escaping, and extended data types such as dates (2024-01-15), binary values and sets. That flexibility comes at a cost: parsers are more complex, and careless indentation can introduce syntactic ambiguity.
What is bidirectional YAML-JSON conversion good for?
This converter is useful for turning Kubernetes or Docker YAML configuration into JSON for JavaScript and TypeScript applications, converting JSON API responses into YAML for more readable configuration files, migrating configuration between tools that use different formats, validating YAML by round-tripping it through JSON, and generating configuration programmatically in JSON before converting it to the YAML that DevOps teams prefer to read.
If you work with this tool, you will probably also find these useful JSON to CSV, CSV to JSON, JSON Formatter, Markdown Preview.
Frequently asked questions
Is any data lost when converting YAML to JSON?
The structural data is preserved in full, but a few YAML-specific elements do not survive: comments disappear because JSON has no equivalent, anchors and aliases are expanded into their full values (duplicating data), special YAML types such as dates become ISO strings, and multiline string formatting collapses into strings containing \n. The semantic information is kept; the documentation and reuse metadata is not.
Why is indentation so critical in YAML files?
YAML uses indentation to define the hierarchy of the data, much like Python. The rules that matter: you must use spaces, because tabs are forbidden by the specification; indentation has to be consistent, typically 2 or 4 spaces; and a change in indentation changes the nesting level. Wrong indentation can silently change the meaning of the document or cause parse errors, so always validate your YAML after editing it.
Is JSON a valid subset of YAML?
Yes. Since YAML 1.2 (2009) every valid JSON document is also valid YAML, and a YAML 1.2 parser can read JSON without modification. That allows mixing the two syntaxes in some cases, although it is rarely a good idea for readability. The practical implication is that you can use YAML tooling to validate and process JSON files, and migrate gradually from JSON to YAML while staying compatible.