Can I sell budget airline flights on my portal alongside the normal airlines?

Yes, you can sell budget airline flights on your portal next to the normal airlines, but it depends on which suppliers you are connected to. Low cost carriers do not sit in the same systems as full service airlines, so they usually reach your portal through a separate connection, or through a supplier who has already done that work. Once both are connected, your customer searches once and sees everything together in the same results.

The difference shows up after the search rather than in it. Budget airlines often sell a bare fare and charge separately for bags, seats and meals, so their first price can look much lower than a full service fare that already includes those things. It is worth making that clear while the customer is choosing, so nobody is surprised at the airport. Many of these airlines also want payment at the moment of booking and will not hold a seat.

Be honest about what you can service afterwards. A lot of budget airlines do not let an agent make changes through an API, so a date change or a name correction can mean going to the airline yourself, or asking your supplier to do it for you. Refunds can be slower, and some fares cannot be refunded at all. That is set by the airline, not by your portal.

Ask your supplier which low cost carriers they cover on the routes you sell most, and what they can and cannot do for you after the ticket is issued, before you promise anything to a customer.