JSON vs YAML: which data format should you use for configs, APIs, and devops?
JSON and YAML are the two dominant human-readable data serialization formats, but they serve different philosophies. JSON is strict, fast, and universally supported by every programming language. YAML is more readable, supports comments and anchors, and has become the default for infrastructure-as-code and CI/CD pipelines.
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JSON's strength is its simplicity: six data types, no surprises, every parser produces the same result from the same input. It's the native format of REST APIs and the lingua franca of web development. YAML's strength is its readability for humans: significant whitespace, comments, multi-line strings, and anchors that let you reuse configuration blocks. The trade-off is that YAML's spec is enormously complex (the 1.2 spec is 84 pages) and different parsers can interpret the same YAML differently, which has led to security vulnerabilities in Kubernetes and Ansible.
Verdict
Use JSON for APIs, data interchange between systems, and anywhere a machine is the primary consumer. Use YAML for configuration files that humans write and maintain, especially in DevOps (Docker Compose, Kubernetes, Ansible, GitHub Actions). For app config, TOML is increasingly preferred over both as a simpler middle ground.
Frequently asked questions
Is YAML a superset of JSON?
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