DTD File — Document Type Definition for XML validation.
Quick facts
What is .dtd
A .dtd file is a DTD File — Document Type Definition for XML validation.
In the mime-db registry it maps to application/xml-dtd, and it is marked as compressible. When serving .dtd over HTTP, set the Content-Type header as shown in Developer info below.
Related entities: it maps to application/xml-dtd — and is delivered over HTTP via the Content-Type header.
How to open .dtd files
Developer info
When served over HTTP, responses should set the following header:
Content-Type: application/xml-dtd
Common software that reads/writes .dtd:
Relation chain
Related extensions
Related MIME types
Common uses
How to edit .dtd files
How to create .dtd files
Frequently asked questions
Common options include VS Code, XMLSpy. You can also open many of these files with built-in viewers or a browser.
Create a new file in any text editor or the app that owns the format and save it with the .dtd extension.
application/xml-dtd is the media type identifier used for .dtd files during network transfer (for example in the HTTP Content-Type header).
Sources & standards
Updated 2026-08-18
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