Top Rideshare Apps in Colombia:
Uber: Considered the best for safety, reliability, and ease of use for tourists, with premium options like Comfort.
Cabify: Often preferred for its professionalism and reliability, frequently used for airport transfers.
DiDi: A popular, generally cheaper alternative to Uber with good availability.
InDrive: A strong choice for lower prices, allowing you to negotiate fares directly with drivers.

Medellin:
Taxis in Medellin are yellow-colored, metered and you can hail them from the street. Minimum fares start at COP 8,300 and street hails are cash only. You can also use radio taxis which are taxis registered to a company who will send them to your location. With these taxis, you'll be given a special code to give to your driver to verify that he/she is indeed from the company.

Cartagena:
Cartagena’s taxis are the most expensive in Colombia. Taxi drivers also have a reputation for overcharging tourists and even locals. Official taxis are yellow, with the words “servicio publico” on their exterior, and the license plate number is affixed to the side passenger door. These taxis are not metered, so you should agree on the price before getting in. The minimum fare is COP 12,250.

Medellin:
The Metro: Medellin's Metro (train) is comprised of two lines: A (north to south) and B (centre to west) that, together, host 27 stations, including ones that will leave you at key touristic sites in the city such as the Plaza de Botero and the Botanical Gardens. The standard metro fare with a personalized Civica card is COP3,650.

UniViajes: To use the Metro, you can buy UniViajes (single passes for a one way trip). They are typically more expensive and meant for casual users or tourists. These can be purchased at any Metro station and If you're going to make several trips on the Metro, you can buy multiple UniViajes for later use.

MetroCable: Composed of 3 lines (J, K, and L) which connect hillside neighborhoods. The cost is included in the initial UniViaje or Metro fare, unless you continue on the CableArvi (line L). You can take the MetroCable to visit places such as the newly constructed Biblioteca España (Spanish Library) or simply to get an aerial view of the city.

MetroPlus: Rapid buses or the MetroPlus have two lines of transport, each with at least one stop connected to the Metro and MetroCable transportation systems. These buses have fixed stops and will not respond to pedestrians waving them down. You'll also need to purchase a ticket for these buses at any MetroPlus station.

Civica Card: It is recommended to get a Civica card when staying in Medellin for a week or more. They are reusable, rechargeable smart cards offering lower fares than UniViajes and integrated travel. They are available at the San Antonio, San Javier, Itagüí, and Niquía stations and will get you access to all public transit carriers (Metro, MetroCable, Metroplús, trams, and feeder buses). To purchase a card, ensure to present a valid ID like a passport. Recharge the Civica Card at green refill machines located at the stations.

Public Buses: These buses have a specific routes in the city that can be identified by a square-like poster in the front window. They charge between COP $1,600–2,150, depending on the bus type (microbus, buseta, or integrated buses). Most fees must be paid in cash, preferably in coins or with small bills although some integrated buses work with Metro cards. Regardless, the buses will always have the current fee posted.

Cartagena:
TransCaribe: The TransCaribe is a bus rapid transit (BRT) network of orange and white buses that use dedicated lanes to serve designated routes throughout the city. The buses circulate from 6am to 11pm Monday through Friday, and weekends until 9pm. Each ride costs COP$3000, but no cash is accepted so you must have a rechargeable TuLlave Card.

TuLlave card: Can be purchased at TransCaribe stations for COP$6000. Top up the card at most stations or other authorized vendors, such as Giros Colombia.

Tip: The free mobile-phone app Moovit provides route information and timetables for taking the bus around Cartagena.

Collective taxis: These are shared taxis that charge a fixed fee per person, ~COP $4,000 and follow a set route. They can be identified on the road by their quick beeps of the horn and the driver holding up their pointer finger or by a line of stopped taxis, usually with someone shouting their route. They are cheaper than regular taxis and can be flagged down like regular taxis.