If you use Obsidian, Hugo, or Jekyll, you've probably seen this error:
YAML front matter parsing error: ...
It usually shows up right when you need the note most. And the worst part? The error message tells you something is wrong, but rarely where.
The three mistakes I kept making
After way too many broken notes, I noticed the same culprits:
- Tabs instead of spaces. YAML forbids tabs for indentation. One pasted tab and the whole block fails.
-
A missing closing
---. You open front matter and forget to close it. -
Unquoted
yes/no/ numbers like007. YAML silently turnsyesintotrueand007into7. For Obsidian tags or version fields, that's a silent data change.
(There's a longer catalog of these at yamltoolbox.com/yaml-errors if you want the full list.)
Why I didn't want to paste my notes into "just any" validator
Most online YAML validators ask you to paste your content into their server. For a config file that's fine. For private Obsidian notes — reading lists, daily journals, work-in-progress — I didn't love the idea.
So I built one that runs 100% in the browser. Nothing is uploaded. You paste the note, it checks only the --- block (so the Markdown body never causes false errors), and shows the exact broken line.
👉 YAML Frontmatter Validator & Fixer
What "fix" actually does
It doesn't rewrite your note into something clever. It does the conservative stuff:
- adds the missing closing
--- - trims trailing whitespace that breaks parsing
- quotes
yes/no/007so they stay strings - reports every change it made, line by line
Before:
---
title: My Note
tags: a, b
draft: yes
---
After:
---
title: My Note
tags:
- a
- b
draft: "yes"
---
The draft field stays "yes" instead of becoming a boolean. Small thing, but it's the difference between a note that renders and one that doesn't.
Validate the rest of your YAML too
The same no-upload rule applies to the plain YAML Validator — handy right before you commit a GitHub Actions or Docker Compose file.
Why I'm writing this
Third-party write-ups get cited far more than your own site does. I'm not claiming this is the only fixer out there — but if you've lost an afternoon to a missing ---, it might save you the next one.
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