OKF Validator
Check whether frontmatter parses correctly.
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OKF YAML frontmatter
YAML frontmatter is the metadata block that lets an OKF Markdown file describe what concept it contains before the body is read.
What YAML frontmatter does in OKF
Frontmatter gives readers, reviewers, and tools a small structured summary before they load the Markdown body. In OKF files, this metadata helps identify the concept type, readable title, summary, source resource, tags, and freshness signal.
Required fields
typenames the concept category. This is the field this site treats as required from the public draft direction.- Use a human-readable value such as
Website Page,API Endpoint,Documentation Topic,Data Table, orAgent Context. - Keep type consistent across related files so bundles are easier to browse.
Optional fields
titlegives the file a readable display name.descriptionsummarizes the concept in one sentence.resourcepoints to the canonical URL, URN, or stable asset identifier.tagsgroups the file with related concepts.timestamprecords the last meaningful update when your workflow has a real date.
Copy-ready frontmatter example
---
type: Documentation Topic
title: API rate limits
description: Explains public API rate limit rules and retry behavior.
resource: https://openknowledgeformat.online/sample/api-rate-limits/
tags: [api, okf, limits]
timestamp: 2026-06-21T00:00:00Z
---Bad example vs fixed example
The bad example below has no valid type field, an empty description, and tags that are not an inline array.
---
title API rate limits
description:
tags: api, okf
---
# API rate limits
This file has broken frontmatter and missing type.Fixed frontmatter example
---
type: Documentation Topic
title: API rate limits
description: Explains public API rate limit rules and retry behavior.
resource: https://openknowledgeformat.online/sample/api-rate-limits/
tags: [api, okf, limits]
timestamp: 2026-06-21T00:00:00Z
---
# API rate limits
Write the reviewed rate limit explanation here.Validation checklist
- Does the file start with
---before the first heading? - Is
typepresent and specific? - Are
titleanddescriptionreadable without opening the body? - Does
resourcepoint to a stable source? - Are
tagswritten as an inline array? - Have you checked the file with the OKF Validator?
FAQ
Common questions
Is YAML frontmatter the same as the Markdown body?
No. Frontmatter is metadata at the top of the file; the Markdown body contains the explanation and source context.
What OKF frontmatter field should I add first?
Add type first, then fill title, description, resource, and tags for clearer previews and validation.
Can tags be a comma-separated string?
This site's validator expects an inline array such as [okf, api, limits].
Where should I see a complete file?
Use the OKF file example guide for a full Markdown file.
Related pages
Check your frontmatter
Paste one Markdown file and fix the metadata before adding the file to a bundle.
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