YAML Tutorial — Syntax, Examples, and Common Errors

YAML (YAML Ain't Markup Language) is a human-readable data format used mostly for configuration files. If you've worked with Docker, Kubernetes, GitHub Actions, or any CI/CD tool — you've written YAML.

Basic YAML Syntax

name: Mani
age: 29
city: Atlanta
skills:
  - JavaScript
  - Swift
  - Python
active: true

No curly braces. No quotes needed for simple strings. Indentation defines structure.

YAML Data Types

# String
name: tinkrkit.dev

# Number
version: 1.0

# Boolean
enabled: true

# Null
value: null

# List
tools:
  - JSON
  - XML
  - YAML

# Nested object
database:
  host: localhost
  port: 5432

Most Common YAML Errors

1. Wrong indentation

YAML uses spaces — never tabs. Mixing them breaks everything.

# Wrong
parent:
	child: value  # tab used here — INVALID

# Correct
parent:
  child: value  # 2 spaces — valid

2. Missing space after colon

# Wrong
name:Mani

# Correct
name: Mani

3. Unquoted special characters

# Wrong — colon in value breaks parsing
message: Hello: World

# Correct
message: "Hello: World"

YAML vs JSON

YAML is a superset of JSON — valid JSON is valid YAML. But YAML is more readable for config files and supports comments (JSON doesn't).

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Use our free YAML Formatter and Validator to check your YAML for errors, format it cleanly, and convert it to JSON. No login required. 100% browser-based.