# Sumatra PDF is a PDF, ePub, MOBI, CHM, XPS, DjVu, CBZ, CBR reader for Windows

On Windows 10 you can make SumatraPDF to be a default viewer for all supported document types.
In that case double-clicking on a file in Explorer will open SumatraPDF to view the document.
Here's how to make SumatraPDF a default PDF viewer:
In Explorer:

- find a PDF file
- right-click to get a context menu
- select `Open with` and then `Choose another app`

From the list, choose SumatraPDF and check "Always use this app to open .pdf files":
You can do the same for other file types supported by SumatraPDF.

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