Currently two crossings to the Republic of Azerbaijan are open for foreign tourists, in addition to the crossing to the Azerbaijani enclave of Nakhchivan).
Astara (Iran) to Astara (Azerbaijan)
A narrow river divides the two towns. Heading out of Iran takes an easy 30 minutes via the pedestrian crossing, but heading out of Azerbaijan on foot is a nightmare of crowded humanity and could take four to six hours. Take the bus or pay somebody to drive you ($US10, five minutes) to the vehicle crossing on the M3. Once out of Azerbaijan, you can use the pedestrian entry into Iran without any fuss. Exchange your rials and manats on the Iranian side. The Iranian exchange offices near the border provide reasonable rates. Near Hotel Şindan on the Azerbaijani side, Kapital Bank has an ATM.
Loathsome night buses to Baku ($US7 to US$10) and daytime minivans to Lənkəran ($US5) start 100m north of Hotel Şindan. An overnight sleeper train to Baku ($US6, 11 hours) leaves Astara around 7pm, but the station is 3km from the border and tickets often sell out. Confusingly, many Azeris count in ‘shirvans’ rather than New Azeri manats (AZN; US$1 equals AZN2). One shirvan means AZN2.
Bileh Savar (iran) to Bilasuvar (Azerbaijan)
Even busier than the Astara crossing, this checkpoint 170km north of Ardabil is only useful if you have your own vehicle. Leaving Iran presents no problems, but expect large queues on the Azerbaijani side. The crossing may be open 24 hours by the time you visit.