Visas are required by all except visitors from Belarus, Georgia, Kazakhstan, Kyrgyzstan, Moldova, Russia, Tajikistan, Turkey, Ukraine and Uzbekistan.
Visa on arrival is availabe at all international airports for visitors from Bahrain, Israel, Japan, Malaysia, Oman, China, Qatar, South Korea, Saudi Arabia, Singapore and Turkey. US passport holders can also obtain a visa on arrival if they travel from New York to Baku on Azerbaijain Airlines.
When applying for a visa you will need an invitation from a state recognised tourist company. Rules vary depending on where you apply and can take time. Visas are valid for 30 or 90 days.
You may be able to obtain a transit visa that is valid for up to 5 days. There is no need for an invitation. Not all embassies issue transit visas.
Visas cost around US$160 without a travel agency voucher and $20 with a voucher.
There is now an eVisa service for Azerbaijan. You still need to organise an invitation.
Azerbaijain Visa on Arrival
The official version on visa information for Azerbaijan
Azerbaijan embassies and consulates - pdf file
Evidence of visiting Nagorno-Karabakh may result in refusal of entry.