How to open Certificate file .509 files
Have you had trouble opening the 509 file on your computer? What are 509 files? We explain what they are and recommend software that we know will open them.
What is 509 file?
Files with 509 extension are associated with internet security of your server, web sites etc.
Certificate file description
The 509 file extension is used to secure your server, web site transactions, logins, webmail and connections with an SSL Certificate. Choose GlobalSign SSL Certificates for the highest levels of strong security, confidence and trust in your web site, corporate assets and online brand.
Mime: application/x-x509-ca-cert
Suggested software to open 509 file

Opera browser
A popular iInternet web browser and communiation suite

Firefox
A popular free web browser from Mozilla

Microsoft Internet Explorer
The default web browser for older versions of Microsoft Windows. Replaced by Microsoft Edge browser.