The bus between Airport and Al Balad is L14.

The city terminal is just outside Palm mall in Al Balad , as also other city buses terminate there.

To use the bus you need to have a ticket / card already, you cannot pay in cash to the driver.

I also tried my credit card on the bus itself, it wouldn’t work, but maybe it depends on the country it is issued. The safe way is to have ticket before you get on the bus.

The automatic ticket machines found at bus stops around the city, would normally print tickets or recharge the bus cards, but seem not to accept credit cards other than Saudian (their app says also that). No cash accepted at the ticket machines unfortunately.

Outside the palm mall there are a few bus company employees, who can issue tickets, or bus cards, or recharge them, and you can pay cash to them (or by credit card too , hopefully).

It is generally an unfriendly bus system, especially at the start of your trip, to get your first ticket / card, even more if you don’t stay near Al Balad (or other similarly serviced points , I don’t know if / where there might be other points like that).

It is good to download their app.

Still, I found it impossible to locate a couple of useful stops of L14 somewhere in the middle of the city, although they were shown clearly on the app map, and on google maps. I got there by taxi, but I didn’t see any bus stops , twice. Very frustrating if you are on your way to your flight. So finally I used a combination of taxi / bus to go to the airport (the bus happened to pass by when I was with the taxi, so I waved to stop and it did).

Another useful bus was the L7, crossing through the city center and terminating at Al Balad too. It also gets relatively near to the bridge to the north corniche, though you need to walk some long way also.

Also useful is the bus L6 if you stay at Al Hamra, which gets you to L7 and others, for more connections.

Every ride is charged extra, so if you use 2 buses the one after the other to get to your destination, they charge you 2 tickets, very inconvenient too.

All city tickets (and L14 too) cost 3.45 rials.

I saw an employye checking tickets once every 10 or so rides.

https://saptco.com.sa/en/qr-jeddah-transport

https://www.jedtc.com.sa/page/Current_Bus_Service

Bolt and similar taxi apps are of good value, and they are unavoidable, since the bus network is very inconvenient.