Where do betting sites get information about matches?

Question

API

It's hard to find a tag. I'm interested in algorithms, do they pull api? Or do they register themselves? It is unlikely that teams register their fights there. Equally interesting are the formulas for calculating coefficients
. Example: egb.com

Answer 1

https://api.pandascore.co/ like this?

Answer 2

Where do betting sites get information about matches?

What? There are tournaments, there is a tournament grid. It's all in the public domain (otherwise! the spectators won't come, the sponsors won't pay - there won't be anything to arrange the tournament for next year).
There is a history of previous matches - you can calculate the likely outcome. From this set the coefficients.