Yes and No. The endpoint node validates the blocks and exposes RPC APIs to the outer world. EN is always needed for your application to interact with the Klaytn network. For those who simply want to try Klaytn APIs, you can try KAS (Klaytn API Service). KAS provides Klaytn Node API service that exposes RPC APIs of Klaytn networks (both Baobab and Cypress) and other useful API services.