JSON vs YAML: When to Use Which
JSON and YAML both describe the same underlying data — objects, arrays, strings, numbers, booleans, null — they just look different on the page. JSON is a strict, minimal syntax originally lifted from JavaScript object literals: every string is quoted, every object key is quoted, commas separate everything, and there’s no way to add a comment. YAML is a superset built for humans to read and edit directly: no required quotes for simple strings, indentation instead of braces, and full support for comments with #.
Where each one wins
JSON wins as a wire format — it’s what almost every HTTP API returns, it parses in one line in every language, and its lack of ambiguity (no tabs-vs-spaces indentation issues, no implicit type coercion surprises) makes it a safe default for machine-to-machine data. YAML wins as a format humans hand-edit directly — Kubernetes manifests, GitHub Actions workflows, Docker Compose files and Ansible playbooks are all YAML because config that a person edits by hand benefits from comments, less punctuation noise, and multi-line string support.
The gotcha to know
YAML’s implicit typing is its sharpest edge: an unquoted yes, no, on, off, or a bare NO country code, can silently parse as a boolean instead of a string in older YAML parsers (the "Norway problem"). If a value must stay a literal string, quote it explicitly.
Need to go from one to the other right now? Use the JSON to YAML or YAML to JSON converter.
Frequently asked questions
Is YAML a superset of JSON?
Nearly — valid JSON is valid YAML in most parsers (YAML 1.2 formalizes this), though some strict YAML 1.1 parsers have edge-case differences.
Which is faster to parse?
JSON, generally — its grammar is simpler and every language has a fast native or standard-library parser; YAML parsing is more complex and typically slower.
Can JSON have comments?
No, standard JSON has no comment syntax at all — some tools support JSON5 or JSONC as an extension, but plain JSON does not.