What Is a .htm File? .htm Format, MIME & How to Open

Quick facts

Extension.htm

File typeHTML Document

MIME typetext/html

CategoryData & Text

Charset—

CompressibleYes

Format familyhtml

What is .htm

What is a .htm file?

A .htm file is a HTML Document — Alias extension for HTML documents.

In the mime-db registry it maps to text/html, and it is marked as compressible. When serving .htm over HTTP, set the Content-Type header as shown in Developer info below.

Related entities: it maps to text/html and is used by HTML among others — and is delivered over HTTP via the Content-Type header.

How to open .htm files

Use Chrome or VS Code to open and edit .htm files.
Any text editor (Notepad, VS Code) can inspect the raw content as text.

Developer info

When served over HTTP, responses should set the following header:

Content-Type: text/html

Common software that reads/writes .htm:

ChromeVS CodeFirefox

Relation chain

.htmextension of

format

htmlserved as

mime type

text/htmlsent via header

http header

Related extensions

Related MIME types

Related programming languages

HTML

.html .hta .htm

Common uses

Configuration files
Data interchange between systems
API request and response payloads
Logs and data exports

How to edit .htm files

Open the file with Chrome, make your changes and save.
Most editors preserve the original formatting and encoding — avoid changing the charset.

How to create .htm files

Create a new file and save it with the .htm extension, or export this format from Chrome.

Frequently asked questions

What programs can open .htm files?

Common options include Chrome, VS Code, Firefox. You can also open many of these files with built-in viewers or a browser.

How do I create a .htm file?

Create a new file in any text editor or the app that owns the format and save it with the .htm extension.

What is the relationship between .htm and the text/html MIME type?

text/html is the media type identifier used for .htm files during network transfer (for example in the HTTP Content-Type header).

Sources & standards

Updated 2026-08-18

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