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YAML Validator

Check YAML parses and find the line where the indentation goes wrong.

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Quick Tool Overview

The YAML Validator reports the line where parsing stops, and — more usefully — shows the structure it actually read as JSON, which is where a key indented one level too far or a port that became a boolean becomes obvious.

What it does
Validates YAML and previews what it parsed to
You give it
Any YAML file
You get back
A pass or a line number, plus the parsed structure
Best for
Debugging CI pipelines and deployment manifests
Developer Tools Free, unlimited use No sign-up Runs in your browser

About the YAML Validator

Almost every YAML failure is an indentation failure, and the error messages real parsers give for one are notoriously unhelpful. This validator reports the line, and it also shows you the structure it actually read — which is usually where the surprise is.

Seeing the parsed result matters more than the pass or fail. A file can be perfectly valid YAML and still be wrong: a key nested one level too deep, a list that became a string because the dash lost its space, a port number that became a boolean because the value was on rather than 443. The JSON preview makes all three obvious at a glance, which reading the YAML does not.

Key features of the YAML Validator

The structure preview

Valid-but-wrong is the real YAML failure mode. Seeing the parsed result as JSON exposes a key nested under the wrong parent instantly.

Type surprises visible

A port that became true, or a version that became a number, shows in the preview where reading the YAML would not.

Errors by line

Parsing stops with the line number rather than a generic complaint about the document.

Indentation problems named

Tabs, a missing space after a colon or a dash, and inconsistent sibling indentation are each reported as themselves.

Live as you type

Both the verdict and the preview update on every keystroke, so a fix is confirmed immediately.

How to use the YAML Validator

  1. 1

    Paste your YAML

    Any config file — Compose, CI, Kubernetes, Ansible or your own.

  2. 2

    Read the verdict

    Green means it parses; red names the line where parsing stopped.

  3. 3

    Check the structure

    The JSON preview shows what the parser actually built, which is where most real bugs show up.

  4. 4

    Fix and re-check

    Both the verdict and the preview update as you type.

Frequently asked questions

That is exactly what the structure preview is for. A key indented one level too far is valid YAML in the wrong place, and the preview shows it nested under the wrong parent.

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