20 MB Markdown sample

A Markdown file of exactly 20,971,520 bytes. It is a valid Markdown file, generated by this site. Compare its checksum and test it with the parser used by your application. Use it wherever you need a 20 MB sample, test or dummy Markdown file.

sample-md-20mb.md

20 MB20,971,520 bytes

Download 20 MB Markdown

Created in your browser in a few seconds, then checked against the SHA-256 checksum. The file is not uploaded anywhere. No sign-up.

Type: text/markdown
SHA-256: cb1ee8bf379c75e14fab665a8b5625cd71bec1a83d31114349052d2e2af85c4e
Delivery: Created in your browser from static generator assets (how it works).

What is in this file

53,506 sections with headings, paragraphs, bulleted and numbered lists, block quotes, fenced code blocks and tables. An HTML comment at the end brings the file to the exact size.

Sections	53,506
Flavour	CommonMark, with GitHub-style tables
Elements	Headings, emphasis, lists, links, quotes, code blocks, tables
Encoding	UTF-8 (ASCII characters only)
Line endings	LF

How the file begins

The opening lines of sample-md-20mb.md, exactly as they appear in the file.

00000000  23 20 53 61 6d 70 6c 65  20 4d 61 72 6b 64 6f 77 |# Sample Markdow|
00000010  6e 20 66 69 6c 65 20 28  32 30 20 4d 42 29 0a 0a |n file (20 MB)..|
00000020  41 20 43 6f 6d 6d 6f 6e  4d 61 72 6b 20 64 6f 63 |A CommonMark doc|
00000030  75 6d 65 6e 74 20 66 6f  72 20 74 65 73 74 69 6e |ument for testin|

Preview

Creates the file in your browser and shows the first 64 KB of it.

Where 20 MB matters

A 20,971,520-byte file: right at the default attachment limit of Outlook, and just under the 25 MB ceilings of Gmail and GitHub web uploads. These are the default limits a file of this size is useful for testing:

System	Limit	Note
Microsoft Outlook	20 MB of attachments by default for internet mail accounts	This file is right at the limit; add a second attachment and it is exceeded.
Gmail	25 MB per message	Under the limit, although email encoding adds about a third in transit.
GitHub web uploads	25 MiB per file added through the browser	Accepted. Pushing with Git allows larger files.
Cloudflare Pages assets	25 MiB per file	The largest round size that can be served as a static asset.
Amazon API Gateway	10 MB payload	Rejected; the upload has to go directly to object storage.
ASP.NET Core (Kestrel)	About 28.6 MB request body by default	Accepted with room for the multipart overhead.

All 20 MB sample files

Use this file for

Finding the first upload limit in a new stack
Testing documentation pipelines
Testing Markdown renderers and editors

Testing notes for Markdown

Markdown may contain raw HTML, so anything that renders user-supplied Markdown needs an HTML sanitiser.
Tables are an extension rather than part of CommonMark, so renderers differ on whether they appear.

Markdown format reference

Technical details

File name	sample-md-20mb.md
Format	Markdown (Markdown)
Extension	.md
MIME type	text/markdown
Size	20,971,520 bytes (20 MB)
Kind	Text
SHA-256	cb1ee8bf379c75e14fab665a8b5625cd71bec1a83d31114349052d2e2af85c4e
Created	2026-10-23
Validation	See the listed size and SHA-256. Small downloads are checked in the browser; verify streamed downloads manually. A hash match does not prove parser compatibility.
Preview	Available on this page
Source	Generated in your browser by this site's generator; not copied from elsewhere
Licence	Free to use, modify and redistribute (terms)
Category	Documents

Check the stated structure and checksum against your application requirements. As with any download, scan the file with your own security tools before opening it. How files are made and checked

Verify your copy

This file is created in your browser, so it has no direct URL for curl or wget. The generator is designed to produce reproducible bytes. After saving, compare the checksum with the SHA-256 value above.

sha256sum sample-md-20mb.md     # Linux
shasum -a 256 sample-md-20mb.md # macOS

On Windows, run Get-FileHash sample-md-20mb.md -Algorithm SHA256 in PowerShell. For scripts and pipelines, save the file once and keep your own copy.

Related files

Questions about this file

Is this file exactly 20 MB?: Yes. It is 20,971,520 bytes, which is 20 MB in the binary units that operating systems and server limits use (1 KB = 1,024 bytes).
What is inside the 20 MB Markdown file?: 53,506 sections with headings, paragraphs, bulleted and numbered lists, block quotes, fenced code blocks and tables. An HTML comment at the end brings the file to the exact size.
Which Markdown features do the samples use?: Headings, emphasis, ordered and unordered lists, links, a pipe table, a fenced code block and a block quote.

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