Validate YAML syntax
Paste YAML and catch the errors that break CI pipelines and Kubernetes manifests — tabs used for indentation, inconsistent spacing, and bad quoting — with the line where it fails.
Open the tool, then paste the sample input below. Everything runs locally in your browser.
The problem
YAML is whitespace-sensitive, so a tab character or an off-by-one indent makes a CI config or a Kubernetes manifest fail to parse, often with a cryptic error. Validating it first points you at the exact line so you can fix it before the pipeline does.
Sample input
name: build
on:
push:
branches: [main]Expected output
Error on line 4: found a tab character where indentation must use spacesLine 4 is indented with a tab. YAML forbids tabs for indentation; replace it with spaces and the document parses.
How to do it
- Paste the YAML document.
- Validate it.
- Read the error and its line number.
- Fix the indentation, tabs, or quoting.
- Re-validate until it parses.
Common mistakes
- Using tabs instead of spaces for indentation.
- Inconsistent indentation between sibling keys.
- Unquoted values that YAML reads as booleans, like yes or no.
- A missing space after a colon in a key/value pair.
- Bad list indentation so items attach to the wrong key.
Related tools
Related guides
FAQ
How do I validate YAML syntax?
Paste the YAML and validate it. If it does not parse, the validator reports the error and the line number so you can find and fix the problem.
Why can I not use tabs in YAML?
YAML forbids tab characters for indentation; it requires spaces. A tab produces a parse error, so replace tabs with spaces.
Why is my value read as a boolean?
YAML interprets bare words like yes, no, on, and off as booleans. Quote the value if you mean the literal string.
What commonly breaks Kubernetes YAML?
Inconsistent indentation, tabs, and missing spaces after colons. Validating first catches these before kubectl rejects the manifest.
Is my YAML uploaded?
No. Validation runs locally in your browser. Your document is not sent to a server.
YAML validation runs locally in your browser. Nothing is uploaded.
Validate and convert YAML and JSON, generate manifests, and format payloads — grouped in one place.