YAML Validator Online
Check, Format And View YAML

What A YAML Validator Online Does For You

YAML runs a lot of the modern web. Config files, build pipelines and cluster settings all use it. But one wrong space can break a whole deploy, and the error message is often vague.

This tool tells you exactly what is wrong. First, paste your YAML and the tool checks it at once. If there is an error, you see the message and the line. Then one click takes you to that spot.

It also finds problems that a parser alone would miss. For example, an unquoted no can turn into false. A number with a leading zero can turn into octal. These checks save real debugging time.

Besides checking, the page has four more modes. It formats and sorts the file, draws a tree, parses it to JSON, and encodes it as Base64. All of them share one box.

Everything runs in your browser. Your YAML never leaves your device. That matters, because config files often hold hostnames, tokens and other private details.

YAML Checker With Clear Errors

First, the validator reads your file the way a real parser does. If it finds an error, it names the line. It explains the problem in plain words, such as a tab used for indentation or a bracket that never closes.

Every error comes with a button called Show me where. It selects the spot in your text. So you fix it in seconds, not minutes. Then the check runs again on its own.

When the file is valid, you still get notes. The notes list risks, such as unquoted yes and no, anchors, comments and trailing spaces.

For more detail, see: YAML 1.2 specification.

YAML Formatter Online

First, switch to Format to tidy the file. Then the formatter rewrites it with clean two or four space indents. It also quotes the values that need quotes, and it keeps block text as a block.

You can sort the keys from A to Z. Sorted files are easy to compare and easy to review. Also, tabs and trailing spaces disappear. Finally, you can paste the clean file back into your project.

This yaml formatter online reads the whole file first. So it never writes broken output. If the YAML has an error, it tells you instead.

YAML Viewer Online As A Tree

Long YAML is hard to read. So the tree mode shows it as branches. Then you can open only the part you need. Each key opens and closes, and the number of items shows beside it.

Strings, numbers and booleans have their own colours. As a result, you see at a glance what the parser thinks each value is.

Parse YAML To JSON

Many tools want JSON, not YAML. So parse mode converts the file at once. The tool expands anchors and merge keys, so the JSON holds the final values.

Then you can copy the JSON or save it as a file. Sorting works here too.

YAML To Base64 And Back

Kubernetes secrets and many CI tools store files as Base64. So this mode encodes your YAML, and it decodes Base64 back to YAML. Also, it works with Unicode text, such as accents and emoji. A URL-safe option swaps the plus and slash characters.

After decoding, the tool checks the text. If it is not valid YAML, you get a note.

The Yes And No Trap

In YAML 1.1, the plain words yes, no, on and off mean true and false. In YAML 1.2, they are text. So the same file can mean different things in two tools. That is why one deploy works and another fails.

For example, the classic case is the country code NO, which turns into false. The validator warns you and suggests quotes. Quoted values are safe in every parser.

Indentation Rules

YAML uses spaces to show structure. YAML forbids tabs. Every child must sit deeper than its parent, and siblings must line up exactly.

Then the tool catches both mistakes and names the line. In short, you never hunt for a stray space by eye.

Also, a key and its value need a space after the colon. A list item needs a space after the dash. These small rules cause many errors, and the tool points at each one.