The title says it, but I also need at least 30 characters.
Etherscan is the most cut-and-dry, but there are at least a couple of other resources available:
- SmartContract.Codes - a p2p search engine for smart contract source code.
- ethPM - a decentralized package manager used to distribute EVM smart contracts and projects.
I'm a big fan of ethPM, but it can take a bit of time to understand. Here are a few more links that might come in useful: