YAML Formatter & Validator

What is a YAML formatter and validator?

A YAML formatter and validator parses YAML for syntax errors, pretty-prints with consistent indentation, and exports JSON—free in your browser, no upload.

Paste → Format YAML → Copy. Invalid YAML shows line, column, and a fix hint before you commit or kubectl apply.

Quick answers

Concise answers for common searches — definitions, steps, and comparisons.

How to use YAML Formatter & Validator

1. 1

   Paste your YAML

   Paste or drop a .yaml file into the editor. With Format on paste enabled, output appears automatically after a large paste.

2. 2

   Click Format YAML

   Press Format YAML or Ctrl+Enter in the editor to pretty-print with consistent indentation. Validation runs in the same step.

3. 3

   Fix errors if needed

   Use Jump to line to scroll to the problem. Strict mode (More → Settings) adds duplicate-key and tag warnings.

4. 4

   Copy or export

   Copy formatted YAML from the output panel, toggle Diff to see what changed, download .yaml, or use More → Copy as JSON.

Who uses a YAML formatter?

Common real-world scenarios where this tool saves time.

Workflow guides

Step-by-step chains that connect related tools for common tasks.

YAML Formatter & Validator examples

services:
  web:
    image: nginx
  ports:
    - '80:80'

Error at line 4 — ports aligned at root, not under web

apiVersion: apps/v1
kind: Deployment
metadata:
name: api
spec:
  replicas: 3

Consistently indented 2-space YAML with metadata.name nested under metadata

name: CI
on: [push]
jobs:
build:
  runs-on: ubuntu-latest

jobs.build indented under jobs with runs-on nested correctly

---
apiVersion: v1
kind: ConfigMap
---
apiVersion: v1
kind: Secret

Two documents separated by --- with consistent spacing

country: NO
enabled: yes

Hint: quote NO and yes if they must be strings in YAML 1.1 parsers

server:
  host: localhost
  port: 8080

{
  "server": {
    "host": "localhost",
    "port": 8080
  }
}

How YAML formatting and validation work

Validation calls yaml.parse on your input after normalizing tabs to spaces. The first parse error yields line and column coordinates mapped to CodeMirror's error gutter and the error panel. Formatting uses Prettier's YAML plugin with your chosen tab width (2 or 4 spaces). The formatted string is semantically equivalent to the parsed document—only whitespace and quoting style may change. JSON export parses to a native object tree, then JSON.stringify with 2-space indent. Strict mode adds non-blocking hints for duplicate keys and risky unquoted scalars (yes/no, octal-looking numbers). Live validation debounces while you type; full Prettier format runs on Format YAML, paste-auto-format, or Ctrl+Enter.

Reference tables

When to use YAML Formatter & Validator vs related tools

Use this formatter for human-edited YAML configs. Switch tools when your source format is JSON or TOML, or when you need schema-level validation.

Best practices

Common mistakes to avoid

Troubleshooting

When this tool isn't the right choice

What to do next

Continue the workflow with the right follow-up tool.

• Document config shape withJSON Schema Generator after exporting JSON from a golden manifest.
• Format TOML configs withTOML Formatter when switching from YAML to TOML in a service.
• Compare two versions withText Diff after copying each formatted output.
• Validate embedded JSON fragments withJSON Validator when CI steps output JSON strings.
• Encode secrets for K8s withBase64 Encoder —still store real secrets in a vault, not git.

Frequently Asked Questions

Privacy, accuracy, and trust

Limitations: Syntax validation confirms parseability. Run kubectl apply --dry-run=server or kubeconform for Kubernetes schema checks.

For development and triage—pair with JSON Schema Generator when documenting config shapes for microservices.

Related Tools

More free tools for the same workflow.