What does shifting heading levels do?

It rewrites the # prefixes so every heading moves up or down by the chosen amount — useful when embedding one doc inside another.

Yes. Levels are clamped between H1 and H6, so you can't accidentally produce ####### headings (which aren't valid Markdown).

Does it update the TOC and anchors?

Heading text is unchanged, so existing anchors keep working. Regenerate the TOC after shifting if your doc relies on one.

Is the document sent to a server?

No. The shift runs entirely in your browser.

bulk-shift # ## ### levels up or down

Shift Markdown heading levels

Promote or demote every heading by N levels in one pass — perfect when embedding a doc inside a larger document or splitting one out.

Heading Leveler

Input

129 B

17 lines

Output

133 B

17 lines

Status

ready

live

Ratio

1.03×

out/in

input · markdown

output · re-leveled

## Project

Intro paragraph.

### Section A

Some text.

#### Subsection A.1

More text.

### Section B

```md
# ignored in fence
```

Quick Start

How to shift heading levels

Adds or removes # characters from every heading line, clamping at H1 (1 #) and H6 (6 #). Fenced code blocks are left untouched.

01
Paste Markdown
Any doc with mixed heading levels.
Parsing runs through marked with GFM extensions enabled — tables, task lists, strikethrough, and fenced code blocks all match GitHub’s rendering.
inputGFMmarkedCommonMarklive
input · markdownmd · GFM
```
# Title
## Sub
```
loaded · GFMGFM · ready
02
Pick shift
+1 to demote, -1 to promote, etc.
Soft-break behaviour is configurable: by default a single newline becomes a space (CommonMark), toggle on for chat-style <br> insertion.
shiftsoft-breaksoptionsconfiglive
mode · options+1 · live
```
shift=+1
```
options applied · livelive
03
Apply
Each heading line gets the level adjustment, clamped to 1–6.
The preview is scoped under a .mde class so its CSS doesn’t bleed into the rest of the page. Output HTML is whitespace-controlled for clean diffs.
applypreviewscoped CSSrenderstable
out · renderedmd · ready
```
## Title
### Sub
```
rendered · liverendered
04
Drop into parent doc
Embed cleanly beneath an outer H1.
Export covers both raw Markdown and rendered HTML; downloads stream as text/markdown or text/html via Blob + object URL.
exportclipboard.md.htmlblob
✓ · exportedfit · done
```
✓ embedded
```
shipped · ready to shipsuccess

Pro tips

Author Markdown that renders everywhere

GFM is the safe default

GitHub-Flavored Markdown is the de-facto baseline (tables, task lists, strikethrough). CommonMark is stricter but ubiquitous as a fallback.

Soft-break behaviour varies

A single newline is a space in CommonMark, a <br> in GFM. Toggle soft breaks when source matters.

Escape inside code fences

Backticks inside fenced blocks need a longer fence — three becomes four. Use ~~~ if your content has many backticks.

Anchors are slugified

GitHub lowercases, strips punctuation, and joins with hyphens. Duplicate headings get -1, -2 suffixes.

Tables need a header row

The dash row sets alignment (:---, :-:, ---:). Use Table Aligner for diff-friendly columns.

Front matter is YAML

Triple-dash blocks at the top of files are parsed by static-site generators. Use the Front-Matter Validator to catch syntax errors.

Use Cases

When to shift heading levels

Adjust structure when documents move around.

README inclusion

Demote a sub-package README before including in a parent. Render path uses marked with GFM extensions enabled (tables, task lists, strikethrough, autolinks), so what you preview matches what GitHub publishes bit-for-bit. Soft-break behaviour is configurable for chat-style vs prose Markdown.

GFM-compliant

Doc consolidation

Merge multiple READMEs by demoting children. Pairs cleanly with the Markdown Cheatsheet for syntax you can't quite remember — callout blocks, footnotes, definition lists. Output stays diff-friendly so style-only changes don't drown out real edits in PRs.

GitHub-perfect

Split-out docs

Promote sections when extracting into a standalone file. Cross-platform safe: anchors, code fences, and tables behave identically on GitHub, GitLab, Bitbucket, and Gitea. Heading-anchor slugs follow GitHub's lowercase-and-hyphenate rules so deep links survive a docs migration.

diff-friendly

Site sections

Match outer-page heading hierarchy in SSGs. No server roundtrip — perfect for proprietary content you can't paste into a public tool. The full marked + GFM bundle ships with the page, so it works offline once loaded.

render-stable

Slide decks

Match required heading levels for Marp / reveal.js. Front matter (YAML / TOML / JSON) passes through unchanged so static-site pipelines (Jekyll, Hugo, Astro, Eleventy) read it correctly. Pair with the Front-Matter Validator to catch syntax errors before deploy.

cross-platform

Cross-import

Adjust before importing into another wiki / CMS. Output is reproducible: identical input always produces identical Markdown, so doc-generation scripts can rely on it for snapshot tests and embedded into release workflows.

SEO-friendly

FAQ

Frequently asked questions

What if a heading would exceed H6?

Levels are clamped — H6 + 1 stays H6. To avoid clamping, restructure manually.

Does it affect setext (===) headings?

No — only ATX (#) headings are modified.

Are code-fenced headings preserved?

Yes. Anything inside ``` is passed through untouched.

Will anchors break?

GitHub auto-anchors use heading text, not level — they survive a level shift. Explicit <a id> anchors also pass through.

Does this run on a server?

No. Leveling runs entirely in your browser.

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