In January 2017 Azerbaijan introduced electronic visas for citizens of 81 countries. The system is called ASAN. The visas are issued for a single-entry visit up to 30 days for a fee of $20.
The e-visa should be printed and presented together with your passport (which should be valid at least 3 months more than the validity period of the electronic visa) at the border checkpoint. Check the list of designated 81 countries on the official MFA website.
Visa to Azerbaijan
Get more details about the Azeri visa at the official Ministry of Foreign Affairs of Azerbaijan website.