Heading Checker (H1–H6)
Paste a fragment of HTML, markdown-style hashes, or lines such as H2: Section name. The outline lists H1 through H6 in the order they appear. A 300 KB limit keeps a very large paste from locking the tab.
Paste HTML or markdown-style headings to build an outline.
Outline
No headings yet. The field is empty, not broken.
When to use a heading outline
Use it after you have a draft article and you want to see the heading tree without opening a full audit. If two H1 headings appear, treat that as a note about structure: readers may not see which line is the page title. The checker does not fetch a URL and does not grade the document.
Examples from this checker
Questions
What formats does the checker read?
It reads <h1> through <h6>, lines that start with one to six hash marks, and lines that begin with H1: through H6:.
Is more than one H1 a penalty?
This page does not assign a penalty. It reports the count so you can decide whether the outline is clear.
What happens with a huge HTML dump?
Pastes over 300 KB are refused with a message. Trim the document to the heading region.