20 MB HTML sample

An HTML file of exactly 20,971,520 bytes. It is a valid HyperText Markup Language 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 HTML file.

sample-html-20mb.html

20 MB20,971,520 bytes

Download 20 MB HTML

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/html
SHA-256: bfeb8944a39dca411cf3999b4af944f47e94de6313fd906a1576dc92e135eb03
Delivery: Created in your browser from static generator assets (how it works).

What is in this file

A static HTML5 page with 25,997 sections of headings, paragraphs, lists and tables. It has no scripts, no external resources and a noindex robots tag. An HTML comment before the closing tags brings the file to the exact size.

Sections	25,997
Doctype	HTML5
Scripts	None
External resources	None
Styles	One inline style element
Encoding	UTF-8 (ASCII characters only)

How the file begins

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

00000000  3c 21 44 4f 43 54 59 50  45 20 68 74 6d 6c 3e 0a |<!DOCTYPE html>.|
00000010  3c 68 74 6d 6c 20 6c 61  6e 67 3d 22 65 6e 22 3e |<html lang="en">|
00000020  0a 3c 68 65 61 64 3e 0a  3c 6d 65 74 61 20 63 68 |.<head>.<meta ch|
00000030  61 72 73 65 74 3d 22 75  74 66 2d 38 22 3e 0a 3c |arset="utf-8">.<|

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 scrapers and HTML-to-text conversion
Testing HTML sanitisers and upload filters

Testing notes for HTML

Serve uploaded HTML with Content-Disposition: attachment or from a separate domain, and send X-Content-Type-Options: nosniff.
A text file that merely starts with a tag can be sniffed as HTML by older browsers if the Content-Type header is missing.

HTML format reference

Technical details

File name	sample-html-20mb.html
Format	HTML (HyperText Markup Language)
Extension	.html
MIME type	text/html
Size	20,971,520 bytes (20 MB)
Kind	Text
Signature	3C 21 44 4F 43 54 59 50 45
SHA-256	bfeb8944a39dca411cf3999b4af944f47e94de6313fd906a1576dc92e135eb03
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-html-20mb.html     # Linux
shasum -a 256 sample-html-20mb.html # macOS

On Windows, run Get-FileHash sample-html-20mb.html -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 HTML file?: A static HTML5 page with 25,997 sections of headings, paragraphs, lists and tables. It has no scripts, no external resources and a noindex robots tag. An HTML comment before the closing tags brings the file to the exact size.
Do the HTML samples run any scripts?: No. They are static documents with one small inline style block, no scripts and no external resources, and they are marked noindex.

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