Is Bitcoin Core required for wallet projects? My team wants to create a cryptocurrency service provider platform to Sell/Buy BTC and something else in form of web/mobile app. It's about one month that I have been studying different articles about its requirements. The crucial things we need in this project are:
1- Creating wallet for customers
2- Let customers to send/receive BTC from/to their wallets  

I found both API providers, and something else like Bitcoin Core, Bitcoind, etc.
We prefer to build our own platform and avoid depending on 3rd party vendors.  May you tell me do we need Bitcoin Core to do our project needs? If your answer is yes, can we install it on a server and access to it remotely via API?
Bitcoin Core is not required to do anything, but it is a useful software that you can use instead of trying to reimplement everything it does. Or you could use some other software that does the same thing. However Bitcoin Core is by far the most used and reviewed software compared to other node and wallet software.



You can use Bitcoin Core to create wallets and let customers send and receive to/from those wallets. However Bitcoin Core is not well optimized for having a large number of wallets (note that a wallet is not the same thing as an address), so it may not be the best for your use case. Of course, if you instead use the traditional model of one exchange wallet and just giving out depositing addresses to users, it's fine (users should not expect to "send from" "their" address).