Comparison · Formats · Guide

JSON vs
YAML

Both describe the same data; they only differ in syntax and tooling. Here is a practical field guide for choosing between them.

JSON
{
  "name": "my-service",
  "replicas": 3,
  "ports": [80, 443],
  "env": {
    "LOG_LEVEL": "info",
    "FEATURE_FLAG": true
  }
}
YAML
name: my-service
replicas: 3
ports:
  - 80
  - 443
env:
  LOG_LEVEL: info
  FEATURE_FLAG: true

JSON vs YAML: Which Should You Use?

JSON and YAML are two popular text formats for structured data. JSON is strict, minimal, and ships with every programming language. YAML is more human-readable but has corner cases that trip up newcomers. Choosing between them comes down to who writes the file and what reads it.

When JSON Wins

JSON is the right call for machine-produced data: REST and GraphQL payloads, log exports, analytics events, inter-service messages, and any format a server generates and a server consumes. It parses in a single line of code everywhere, there is no indentation to break, and the specification fits on a postcard.

When YAML Wins

YAML shines when humans write the file: Kubernetes manifests, GitHub Actions workflows, CI/CD pipelines, Ansible playbooks, docker-compose, dotfiles, and configuration you expect people to review and edit. Comments, anchors, and multi-line strings make YAML genuinely nicer for config.

Common Pitfalls

  • YAML's Norway problem: country: NO parses as boolean false in YAML 1.1 — quote the string
  • Tabs: YAML disallows tabs for indentation; use spaces
  • JSON duplicate keys: parsers may silently drop them; linters help
  • YAML version differences: 1.1 vs 1.2 handle booleans differently
  • Floating-point surprises: both formats inherit JavaScript/Python number quirks

Interoperability

Every JSON document is also valid YAML. Converting YAML back to JSON is lossless as long as you avoid YAML-only features (anchors, non-string keys, complex tags). Use our JSON ↔ YAML converter to flip between the two instantly in your browser.

Decision Rule

If a machine writes it, pick JSON. If a human writes it and will review it in a pull request, pick YAML. For anything in between — mixed authorship, strict schemas, large files — JSON with a formatter is usually the safer bet.

JSON for machines

APIs, logs, exports — fast, strict, universal.

YAML for humans

Config files reviewed in PRs — comments and anchors help.

Convert either way

Any JSON is valid YAML; use a converter when systems disagree.