YAML vs JSON: Which Should You Use?

YAML and JSON represent the exact same data model — objects, arrays, strings, numbers, booleans, null — so converting between them never loses information. What's actually different is who's expected to read and edit the file, and that's what should decide which one you reach for.

What YAML adds

YAML uses indentation instead of braces and brackets, drops most of the quoting JSON requires, and supports comments with # — something JSON has no syntax for at all. A YAML file describing a config is noticeably shorter and easier to scan than the equivalent JSON, which is exactly why it took over as the format of choice for anything a person is expected to hand-edit: Kubernetes manifests, CI pipeline definitions, Docker Compose files.

What that readability costs you

Indentation-sensitivity means a misplaced space silently changes structure instead of throwing an obvious syntax error the way a missing brace does in JSON. YAML also has a genuinely famous gotcha nicknamed the "Norway problem": an unquoted no or yes in a YAML file parses as the boolean false or true, not the string, which has broken real configs where country: no (Norway's ISO code) silently became country: false. JSON's stricter, more verbose syntax makes that class of bug impossible — a string is always quoted, full stop.

Where each one actually wins

YAML wins wherever a human is the primary editor and comments help explain why a setting is set the way it is. JSON wins wherever a program is writing or reading the data without a person in the loop — API responses, data interchange between services, anything parsed by code far more often than it's read by eyes. JSON's stricter grammar is also easier to parse correctly and unambiguously across different languages and tools, which matters more the more machines are involved.

The practical rule

If people will regularly hand-edit the file and benefit from comments, use YAML. If the file is primarily produced and consumed by code, use JSON — you lose nothing structurally by choosing either one, since the underlying data model is identical.

Our YAML to JSON and JSON to YAML converters handle both directions instantly in your browser.