YAML Frontmatter Validator & Fixer
Validate and auto-fix YAML front matter instantly — no upload, fully private. 100% free.
Built for Obsidian, Hugo, Jekyll, and CI pipelines.
How to use
- Paste your full note (including the --- front matter --- block) into the box.
- Click Validate to check it, or Fix & beautify to auto-correct and reformat it.
- The fixed version appears on the right, with a list of exactly what changed.
Paste a whole note and this tool validates only the YAML between the --- delimiters, ignoring the body text. Click Fix & beautify to auto-correct common issues.
Example
---
title: My First Note
date: 2026-08-21
tags: [yaml, notes]
draft: false
---
# Heading
Body text that is not YAML and is safely ignored by the validator.✓ VALID — YAML frontmatter parsed successfully.
Front matter lines: 4
File line range: 1 to 6
No warnings. Your front matter looks good.When this works best
It only understands the YAML between --- delimiters; it will not validate the Markdown body, and it cannot auto-fix syntax that never parses at all.
How it differs from related tools
The YAML Validator checks any YAML document, while this tool is specialized for the --- front matter block of Markdown notes and can also auto-fix it.
Frequently asked questions
Does this validate the whole markdown file?
No. It only checks the YAML between the --- delimiters and ignores the note body, so markdown text never causes false errors.
Is it private?
Yes. Validation runs entirely in your browser; nothing is uploaded.
Will it complain about my Markdown body?
No. Only the YAML between the --- delimiters is checked, so normal Markdown text never causes false errors.
Can it fix tab indentation?
Yes. Click Fix & beautify and TAB characters are replaced with spaces so the block parses.