What Is a CSR File?

How to open, edit, & convert CSR files

A file with the CSR file extension is a Certificate Signing Request file used by websites to authenticate their identity to a Certificate Authority.

CSR files are partially encrypted, with the encrypted portion describing the domain, email address, and country/state of the applicant. 

Also included in a CSR file is the public key. The CSR file is created using the public key and the private key, the latter of which is for signing the CSR file.

CSR files in Windows 10

CSR is also an abbreviation for some other technical terms, but none of them have anything to do with the CSR file format described on this page. Some examples include cell switch router, customer self-repair, content service request, and control and status register.

How to Open a CSR File

CSR files can sometimes be opened with software such as OpenSSL or Microsoft IIS.

You could also open a CSR file with a text editor, but it probably wouldn't be useful. Since the primary information in a CSR file is encrypted, a text editor would serve only to show garbled text when viewed as a text file.

If you find that an application on your PC does try to open the CSR file but it's the wrong application or you'd rather have another installed program open CSR files, you can change the default program that opens CSR files.

How to Convert a CSR File

Most file formats can be converted into other formats with a free file converter. CSR files are a bit different, and so there aren't very many dedicated CSR converters available. For example, a PNG file is popular enough that lots of free image file converters can save it to a different format, but that's not really the case with CSR files.

The easiest way to convert CSR to PEM, PFX, P7B, or DER certificate files is with the free online SSL Converter at SSLShopper.com. Upload your CSR file there and then choose an output format to save it to.

  1. Go to SSLShopper.com.

  2. Under Certificate File to Convert, select Choose File.

    The SSL Shopper website.
  3. In the Open dialog, select the file to convert and select Open.

    Browsing for a CSR file.
  4. Under Type of Current Certificate, select the type.

    Selecting the current certificate type.
  5. Under Type to Convert To, select the type you wish to convert.

    Selecting conversion type.
  6. Select Convert Certificate.

Still Can't Open the File?

One reason for why you can't open your file might be that you're misreading the file extension and confusing another format for the Certificate Signing Request format. There are lots of file extensions that look like they read ".CSR" when they're really just similar looking.

Some examples can be seen with CRS, CSH, CSV, CSS, and CSI files. Although they might like they have something in common with CSR files, beyond their file extension letters, they're actually totally different kinds of files that are opened with different programs.

Double-check the file extension your file is using and then use that as research for help finding out which software programs can open or convert your file.