I am building a DeFi project and I need to interact with existing protocols like Uniswap on my local testnet. How do I actually fork the mainnet so I can test my interactions against live state? I am using Foundry right now—does it have built-in support for this, or do I need another tool? I want to make sure my logic handles real market conditions before I ever deploy to a public chain.
Foundry supports mainnet forking via the anvil tool by using the --fork-url flag to connect a local node to an RPC provider for real-time state replication.
1 answer
Yes, Foundry has built-in support for mainnet forking through the anvil command line tool or your foundry.toml configuration. Simply pass the --fork-url flag with an RPC provider endpoint like Alchemy or Infura to start a local node initialized at a specific block height.
This approach is the industry standard for local integration testing because it replicates state without the latency of public testnets.
