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How do I convert JSON to YAML or YAML to JSON online?

Paste JSON on one side to convert it to YAML, or paste YAML to convert it to JSON. The tool handles nested objects, arrays, multiline strings, and comments. Conversion is instant and runs entirely in your browser with no data sent to a server.

Convert JSON config to YAML
Input
{"server":{"host":"localhost","port":3000},"debug":true}
Output
server:
  host: localhost
  port: 3000
debug: true
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JSON ↔ YAML Converter

Convert between JSON and YAML formats. Perfect for Kubernetes configs, CI/CD pipelines, and configuration files.

About JSON ↔ YAML Conversion

  • JSON (JavaScript Object Notation) — strict syntax with quoted keys, used for APIs and data exchange.
  • YAML(YAML Ain't Markup Language) — human-friendly format using indentation, popular for configs (Kubernetes, Docker Compose, GitHub Actions, etc.).
  • Swap button carries output to input for round-trip conversion.
  • Sample data uses a Kubernetes Deployment manifest — a real-world use case for this tool.
  • Everything runs in your browser — no data is sent over the network.

Tips & Best Practices

Common Pitfall

YAML has dangerous implicit type coercion

In YAML, the value no is parsed as boolean false, not the string "no". Similarly: on/off, yes/no, true/false, and even country codes like NO (Norway) become booleans. Version numbers like 1.0 become floats (losing the trailing zero). Always quote strings that could be misinterpreted: country: "NO", version: "1.0".

Security Note

YAML deserialization can execute arbitrary code

YAML supports language-specific tags like !!python/object that can instantiate objects during parsing. This has led to critical RCE vulnerabilities in Ruby on Rails, Python, and Java applications. Always use safe loaders: yaml.safe_load() in Python, YAML.safe_load() in Ruby, js-yaml's safeLoad() in JavaScript.

Pro Tip

JSON is valid YAML (mostly)

YAML 1.2 is a superset of JSON — any valid JSON document is valid YAML. This means you can use JSON syntax within YAML files for complex nested structures while keeping simple top-level config in YAML format. However, JSON with duplicate keys may behave differently in YAML parsers.

Real-World Example

Use JSON for machine-to-machine, YAML for human-edited config

JSON's strict syntax (required quotes, no comments) makes it ideal for APIs and data interchange — there's no ambiguity in parsing. YAML's comments, anchors, and clean syntax make it better for config files (docker-compose, Kubernetes, CI/CD). Don't use YAML for data storage or API responses.

Frequently Asked Questions

What is the difference between JSON and YAML?
JSON uses braces, brackets, and quotes with a strict syntax — it is great for machine parsing and APIs. YAML uses indentation-based syntax with no braces or quotes for most values — it is easier for humans to read and write. JSON does not support comments; YAML does. JSON has fewer data types; YAML supports dates, timestamps, and multi-line strings natively. YAML is a superset of JSON — all valid JSON is valid YAML. JSON is the standard for APIs and data exchange. YAML is preferred for configuration files (Kubernetes, Docker Compose, GitHub Actions, Ansible).
How do I convert JSON to YAML?
Paste your JSON into DevBolt's JSON-YAML Converter and click the YAML output tab. The converter transforms JSON objects into YAML mappings, arrays into YAML sequences, and preserves data types. Nested objects become indented blocks. Strings that could be ambiguous (containing special YAML characters) are automatically quoted. The output is valid YAML that can be used directly in Kubernetes manifests, Docker Compose files, CI/CD configs, and other YAML-based tools. You can also convert YAML back to JSON with the reverse operation.
Why do Kubernetes and Docker use YAML instead of JSON?
Kubernetes and Docker Compose use YAML because it supports comments (essential for documenting complex configs), is more readable for deeply nested structures (indentation vs braces), requires less syntax for the same content, and supports multi-line strings without escaping. YAML reduces configuration errors because the structure is visually apparent. However, Kubernetes actually accepts both JSON and YAML — you can submit JSON manifests to kubectl. Many teams write YAML for readability but generate it from code or templates in JSON-native languages like JavaScript and Go.

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