Sofia to Belgrade Nikola Tesla Airport bus with Karat-S

Karat-S is a prominent bus operator based in Sofia, Bulgaria, with an extensive transportation network across Europe. The company offers both national and international bus services, connecting various cities in countries like Germany, France, Italy, Spain, and Serbia, in addition to numerous routes within Bulgaria. Karat-S is known for its affordable and punctual services, making it a popular choice for both tourists and daily commuters. Amenities often include air conditioning, adjustable seats, and sometimes Wi-Fi and restrooms, though availability can vary by vehicle. Karat-S operates over 18 daily departures and has a strong presence with offices and points of sale across Europe.

"City Lines" can refer to several different bus companies. One prominent example is Citylines, a leading Bulgarian bus company headquartered in Sofia. It operates an extensive network of 44 routes, connecting 22 cities across Bulgaria and serving 9 European nations with an average of 19 trips daily. Citylines coaches offer amenities such as air conditioning, onboard restrooms, and Wi-Fi connectivity. Another is Rochester City Lines, a family-owned and operated charter bus company in Minnesota, United States, providing services for college, corporate, event, religious, school, and workforce transportation. They offer a fleet including motorcoaches, minibuses, and executive vans. Historically, National City Lines, Inc. (NCL) was a significant public transportation holding company in the United States, founded in 1920. NCL acquired numerous local transit systems, often converting streetcar lines to bus operations, a practice sometimes referred to as "bustitution." Additionally, "City Line" is also the name of a bus rapid transit (BRT) line in Spokane, Washington, operated by the Spokane Transit Authority. This 6-mile route, which opened in 2023, utilizes modern, zero-emission battery-electric buses and connects key areas including downtown Spokane and the University District.