formatter.input (YAML)
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formatter.yaml.advancedOptions
formatter.output
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YAML looks simple. Until it isn't.
A single wrong indentation level. A tab character where a space should be. A colon with no space after it. Any of these can silently break your Kubernetes deployment, your GitHub Actions workflow, or your Docker Compose stack. That's what this tool is for. Paste your YAML above, and get instant formatting, validation, and error feedback — before your pipeline does it for you the hard way.
YAML (YAML Ain't Markup Language) was designed to be the most human-friendly data serialization format available. But that same simplicity hides a minefield of edge cases that trip up even experienced developers:
Unlike JSON or XML, whitespace defines structure. Two spaces vs four spaces isn't a style choice — it changes the meaning of your document entirely.
YAML explicitly forbids tab characters. Copying YAML from Slack, email, or PDFs can silently introduce invisible invalid characters.
NO becomes false. 1.0 becomes a float. Implicit type conversions can cause hard-to-find configuration bugs.
Special characters like :, #, and * need quoting. Forgetting quotes causes parser errors or unexpected behavior.
Normalize indentation, align keys, and fix formatting instantly. Turns messy, inconsistent YAML into clean, readable code.
Checks against YAML 1.2 spec. Flags duplicate keys, bad indentation, tabs, and unclosed quotes with clear error messages.
Convert YAML to JSON instantly. Perfect for generating API payloads, configs for tools that require JSON, or debugging.
Transform YAML into well-formed XML for enterprise systems and legacy integrations without writing manual transformation code.
Strip comments and unnecessary whitespace to reduce file size while preserving the exact structure and values.
Your keys, secrets, and configs never leave your browser. 100% local processing for maximum security.
YAML is the language of modern infrastructure. Here's where our tool helps:
# Example: Kubernetes Deployment
apiVersion: apps/v1
kind: Deployment
metadata:
name: my-app
labels:
app: my-app
spec:
replicas: 3
selector:
matchLabels:
app: my-app
template:
metadata:
labels:
app: my-app
spec:
containers:
- name: my-app
image: my-app:1.0.0
ports:
- containerPort: 8080Every resource is YAML. A misaligned field can deploy incorrectly configured containers. Validate before `kubectl apply`.
Indentation errors in `.github/workflows/` break pipelines. Validate workflow files locally to save broken commits.
Service definitions, volume mounts, networks — all YAML. Keep complex Compose files readable and valid.
Ansible uses YAML for everything. Validating playbooks before running against production infrastructure is critical.
Colon must be followed by a space.
name: Alicename:Alice (error)Use spaces only. Never tabs. Indent children consistently.
server: host: localhost port: 8080
List items denoted with a dash and space.
tags: - developer - python
Quote special chars: : # * etc.
desc: "Port: 8080"title: My AppUse # for comments. Ignored by parsers.
# Database Config
host: localhostQuote ambiguous values.
country: "NO"
active: "true"Best for: Infrastructure & CI/CD.
Human-readable, supports comments, multi-line strings, anchors. Whitespace sensitive.
Best for: APIs & Data Exchange.
Strict, universal, easy to parse. No comments, verbose brackets/commas.
Best for: App Configuration.
Explicit and easy to read. Less widely supported in major DevOps tools.
Use anchors (&) and aliases (*) to define a value once and reuse it throughout the document. This drastically reduces repetition in complex configs.
In the example, service-a and service-b both inherit all values from defaults.
defaults: &defaults environment: production region: us-east-1 timeout: 30 service-a: <<: *defaults name: auth-service service-b: <<: *defaults name: payment-service
Syntax validity != Semantic correctness. We check syntax (indentation, structure). We can't know if your Kubernetes manifest property names are correct for your API version.
YAML 1.2 fixed booleans (only true/false are boolean). In 1.1, yes/no/on/off were also boolean. Most modern tools use 1.2, but be careful with older parsers.
No. The specification forbids it. We detect them and flag them as errors.
In YAML 1.1 'NO' is a boolean false. In 1.2 it's a string. Always quote country codes like "NO" to be safe.
Yes. Use the convert option. We preserve all data structures.
Yes. Processing is local to your browser. Nothing is sent to our servers. Be mindful of your own clipboard/screen.
Yes. Documents separated by `---` are handled correctly.
Start of a document. Optional for single files, required for multi-doc files.
Yes. Responsive design works on phones/tablets.
Designed for readability. Less visual noise, assuming consistent indentation.
Paste your YAML config and catch errors in seconds
Free, private, and works right in your browser.