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.

What is the MIME type of an HTML file?

The MIME type is text/html. The file extension is .html.

Is a sample HTML file the same as a dummy or example HTML file?

Yes. Sample, test, dummy and example HTML files are different names for the same thing: an HTML file with known contents that stands in for a real one. Any file on this page will do wherever a tutorial or a test plan asks for a dummy HTML file.

Free HTML sample files

The markup language of web pages. As an upload it needs careful handling because browsers will execute it. Download valid HTML test files in 4 exact sizes, from 1 KB to 1 MB, each with a checksum.

Extension: .html
MIME type: text/html
Kind: Text
Category: Documents

HTML files by size

Every file below is a valid HyperText Markup Language file of exactly the stated size. Open a file's page for its checksum and contents, and to preview it in your browser before downloading.

HTML sample files by size
File	Size	Contents	Download
1 KB HTML samplesample-html-1kb.html	1 KB1,024 bytes	Sections: 0	Download HTML
10 KB HTML samplesample-html-10kb.html	10 KB10,240 bytes	Sections: 17	Download HTML
100 KB HTML samplesample-html-100kb.html	100 KB102,400 bytes	Sections: 181	Download HTML
1 MB HTML samplesample-html-1mb.html	1 MB1,048,576 bytes	Sections: 1,865	Download HTML

What is an HTML file?

HTML describes the structure of a web page with nested elements such as headings, paragraphs and links. Browsers parse it very forgivingly, following the rules of the WHATWG HTML Living Standard.

An HTML file that a site stores and serves back from its own domain runs with that site's privileges, which is why user-uploaded HTML is a well-known source of cross-site scripting.

How to recognise an HTML file

3C<21!44D4FO43C54T59Y50P45E

The first bytes of every file. Typical, not required. Browsers sniff HTML from several leading patterns.

Extension	.html
MIME type	text/html
Standard	HTML Living Standard (WHATWG)
Extensions	.html and .htm
Encoding	UTF-8, declared with <meta charset>
Can contain	Markup, inline CSS, scripts, references to external resources

What to test for

These are the behaviours that most often go wrong when software handles HTML files.

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.

Strengths of HTML

Opens in every browser with no extra software.
Parsers are extremely forgiving, so imperfect markup still displays.

Limitations of HTML

A complete page usually depends on separate CSS, script and image files.
Executes in the browser, so untrusted HTML is a security risk.

Typical uses of HTML test files

Testing HTML sanitisers and upload filters
Checking Content-Type and Content-Disposition handling
Testing scrapers and HTML-to-text conversion

Software that opens HTML

All web browsers
Code editors and IDEs
HTML parsers such as html5lib, jsdom and Beautiful Soup

Specifications

HTML sample files: questions

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.
What is the MIME type of an HTML file?: The MIME type is text/html. The file extension is .html.
Is a sample HTML file the same as a dummy or example HTML file?: Yes. Sample, test, dummy and example HTML files are different names for the same thing: an HTML file with known contents that stands in for a real one. Any file on this page will do wherever a tutorial or a test plan asks for a dummy HTML file.