There are lots of questions about pairing programs here, some of them mention being authorized by FIDE, but how can I check and know which programs are currently authorized?
FIDE publish a list of such programs here.
Currently there are 8 programs on the list varying in price from completely free (STOP), free on Linux (Vega), partially free (ChessManager) to 150 euros (Swiss Manager).
Program - Author
Vega - Luigi Forlano (ITA)
SwissSys - Thad Suits (USA)
SwissMaster - Royal Dutch Chess Federation (NED)
Swiss-Manager - Heinz Herzog (AUT)
Swiss-Chess - Franz-Josef Weber (GER)
UTU Swiss - Neil Hayward (UK)
ChessManager - Tomasz Żyźniewski (POL)
STOP - Alexander Lenhard (GER)
The landing experience also varies widely. Most are excellent, giving you useful information about provided functionality and limitations upfront, but some are appalling.