What is a REQ file?
A .REQ file is primarily a Certificate Signing Request (CSR) file. System administrators use these files to apply for a digital identity certificate from a Certificate Authority. They contain encrypted information about a server or organization, formatted using the PKCS #10 cryptographic standard. A small number of .REQ files are Canon SD Card Version Request files, used by Canon cameras to manage firmware updates.
How to open REQ files?
You can open standard .REQ certificate files using text editors like Notepad++ or command-line tools like OpenSSL. Because they usually contain Base64 encoded text, they are easy to view, but decoding the actual certificate details requires specialized software or cryptographic commands.
Identify and Convert
Because the .REQ extension has multiple possible meanings, we recommend using viewer.online/req to identify the actual format of your file. viewer.online/req analyzes .REQ files to identify their exact format and creator software, shows which programs can open the file, and usually previews it. If you need a different format, you can convert your file to .CSR, .PEM, or .TXT using convert.guru.
Summary
Because .REQ files use the known certificate?? format, viewer.online/req can safely open and display them online, eliminating compatibility problems.