# Supported file types

Sinch Fax API supports the following file types:

- Microsoft Word documents (.docx)
- HTML documents (.html)
- Images(.jpg, .png, .tif)
- PDFs (.pdf)
- Plain text files (.txt)


Fax to Email feature supports the following file types:

- Microsoft Word documents (.docx)
- PDFs (.pdf)
- TIFFs (.tif)


We recommend that you send either an image like a .png or a PDF to keep any formatting on the document.

## PDF considerations

Some PDFs are editable or form-fillable. To preserve the information entered in these form fields, you should "flatten" the PDF. You can flatten a PDF using the following methods:

- Using software like [Adobe Acrobat](https://www.adobe.com/acrobat/hub/how-to-flatten-a-pdf.html)
- Print to PDF using your browser ([Chrome](https://support.google.com/chrome/answer/1069693?hl=en&co=GENIE.Platform=Desktop), [Edge](https://support.microsoft.com/en-us/microsoft-edge/print-in-microsoft-edge-38f38d80-d55c-01a6-528d-467cdd8ada2d), [Safari](https://support.apple.com/guide/safari/print-or-create-a-pdf-of-a-webpage-ibrw1060/mac), [Firefox](https://support.mozilla.org/en-US/kb/how-print-web-pages-firefox))