DevFormat
Back to Guides

JSON vs YAML: Which Format Should You Use?

The battle of the configuration formats. JSON is strict and ubiquitous; YAML is clean and powerful. Here is how to choose.

At a Glance

FeatureJSONYAML
CommentsNoYes (`#`)
SyntaxBraces and QuotesIndentation (whitespace)
Parsing SpeedVery FastSlower (complex grammar)
Primary UseAPIs, Web DataConfiguration, DevOps

Detailed Breakdown

1. Readability

YAML wins here. Its lack of brackets and quotation marks makes it look like a natural outline. This is why it is preferred for configuration files (Docker Compose, Kubernetes) that are manually edited by humans.

JSON

{
  "name": "John",
  "age": 30,
  "skills": ["dev", "ops"]
}

YAML

name: John
age: 30
skills:
  - dev
  - ops

JSON is denser. While improved by pretty-printing, the visual noise of punctuation can make large files harder to scan.

2. Features

YAML is a superset of JSON, meaning it can do everything JSON can do, plus more. YAML supports:

  • Comments: Essential for documenting why a configuration value is set.
  • Anchors & Aliases: Allow you to define a block of data once and reference it multiple times (dry).
  • Complex Types: YAML can explicitly tag data types.

3. Safety & Parsing

JSON parsers are simple, fast, and secure.

YAML parsers are complex. The "Norway Problem" is a famous example where the country code `NO` (Norway) was interpreted as the boolean `false` by some YAML parsers.

Conclusion

  • Use JSON for APIs, data interchange between services, and when you need maximum performance and compatibility.
  • Use YAML for configuration files, CI/CD pipelines, and scenarios where humans will read and write the file frequently.

Need to switch? Use our free JSON to YAML Converter.