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SEOCode Rules Update v1.3.6

#release #rulesupdate #newrules 
---
title: "Rule Engine Update 1.3.6: HTML Is the SEO Standard, Not Markdown"
date: 2026-06-18
version: 1.3.6
slug: rule-engine-update-1-3-6
description: "SEOCode 1.3.6 adds one new informational rule clarifying that Markdown files served as content carry no SEO advantage over HTML, per Google's own guidance."
tags:
  - rule-engine
  - changelog
  - technical-seo
  - html
  - markdown
---
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Rule Engine Update 1.3.6: HTML Is the SEO Standard, Not Markdown

Version 1.3.6 adds one new informational rule based on explicit guidance from Google: serving content as Markdown files provides no SEO advantage over HTML, and HTML remains the canonical document format for Google Search.

New Rules

html-standard-for-seo — Markdown files have no SEO advantage over HTML

Severity: Info

Category: Technical

What the rule checks

This rule flags cases where content is being served directly as Markdown files — for example, .md files exposed at a public URL, or llms.txt-style Markdown documents intended to carry indexable content. It surfaces a warning when your repository appears to be routing Markdown files as primary content endpoints rather than rendering them as HTML before serving.

Why it matters for SEO

Google has stated directly that HTML is the standard for SEO, not Markdown. Google's crawlers and ranking systems are built around HTML as the document format of the web. A Markdown file served at a URL is not treated as an equivalent substitute for a properly structured HTML page. If you are publishing content you want to rank — articles, documentation, landing pages — and that content is being delivered as raw Markdown rather than rendered HTML, you are working against how Google's systems are designed to process and evaluate pages.

This rule complements the existing llms-txt-not-required rule. That rule addresses the specific pattern of creating llms.txt files for AI crawlers. This rule addresses the broader question: even setting aside AI-specific files, Markdown as a general content delivery format is not a recommended or advantaged format for SEO.

What you need to do

If this rule fires on your PR, check whether the files being added or modified are:

  1. Served directly as .md files at a public URL — If so, consider whether those files should be rendered to HTML before being served. Most static site generators (Jekyll, Hugo, Eleventy, Next.js, etc.) do this automatically. Verify your build pipeline is not accidentally exposing raw Markdown at canonical URLs.
  2. Intended only as source files — If the .md files are build inputs that get compiled to HTML, and the HTML output is what gets served and indexed, no action is needed. The rule is informational and may not apply to your setup.
  3. Intended as AI-readable documents — See llms-txt-not-required for guidance on that specific pattern.

No code change is required if your Markdown files are already being rendered to HTML by your build process. This rule exists to catch cases where that rendering step is missing or bypassed.

Sources & References

  1. Search Engine Roundtable — "Google: HTML The Standard For SEO, Not Markdown Files" (scraped 2026-06-18)

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