The H1 tag is the primary heading of a page - it tells both users and search engines what the page is about. When a page has no H1 tag, search engines lose a key signal for understanding the page’s topic, and users lose the visual hierarchy that helps them scan content quickly.

This guide shows you how to find every page missing an H1 tag using the crawler.sh CLI.

Step 1: Install crawler.sh CLI

Install the CLI with a single command:

curl -fsSL https://install.crawler.sh | sh

This downloads the correct binary for your operating system and architecture, places it in ~/.crawler/bin/, and adds it to your PATH. Restart your terminal or run source ~/.bashrc (or ~/.zshrc) to pick up the new PATH entry.

Verify the installation:

crawler --version

Step 2: Crawl the target website

Run a full crawl of the website you want to audit:

crawler crawl https://example.com

The crawler checks for H1 tags on every page it visits. Results are saved as an NDJSON file (.crawl) in the current directory. For larger sites:

crawler crawl https://example.com --max-pages 5000

Step 3: Run SEO audit

Run the SEO analysis on your crawl data:

crawler seo example-com.crawl

The missing H1 check flags every page where no <h1> element was found in the HTML.

Step 4: Identify missing H1 tags

Look for the Missing H1 section in the SEO report. Pages commonly missing H1 tags include:

Pages where the H1 is rendered via JavaScript and not in the initial HTML
Pages that use H2 or other heading levels for the main heading
Landing pages that rely on images or styled divs instead of semantic headings
Pages built with visual editors that skip heading structure
Error pages and utility pages

Step 5: Fix and re-crawl

Add a single, descriptive H1 tag to every flagged page:

Use the H1 for the page’s main topic - it should match or closely relate to the title tag
Keep it concise - between 10 and 70 characters
Use only one H1 per page - use H2–H6 for subheadings
Ensure it is in the HTML source - not just rendered by JavaScript

After fixing, re-crawl to verify:

crawler crawl https://example.com
crawler seo example-com.crawl

Why missing H1 tags matter for SEO

The H1 is one of the strongest on-page SEO signals after the title tag. Search engines use it to understand the page’s primary topic and match it to search queries. The H1 also serves as the main heading for screen readers, making it critical for web accessibility. Adding proper H1 tags improves both search rankings and the experience for all users.