Testnets

How to develop and test on Sepolia and Solana Devnet before deploying to mainnet.

What is a testnet

A testnet is a separate blockchain network that mimics a mainnet but uses tokens with no real-world value. Testnets let you:

• Test agent logic without risking real funds
• Simulate DeFi interactions before going live
• Experiment with contract calls and policy configurations
• Iterate quickly without worrying about transaction costs

Testnet tokens are freely available from faucets — services that dispense small amounts on request.

Cobo testnet support

Cobo chain ID	Testnet	Mirrors
SETH	Ethereum Sepolia	ETH (Ethereum mainnet)
TBASE_SETH	Base Sepolia	BASE_ETH (Base mainnet)
SOLDEV_SOL	Solana Devnet	SOL (Solana mainnet)

Getting testnet tokens

Cobo provides a built-in faucet that lets you request small amounts of testnet tokens.

Faucet requests are rate-limited. For high-volume testing, you can also use public testnet faucets provided by the blockchain networks themselves:

• Ethereum Sepolia: sepoliafaucet.com
• Base Sepolia: docs.base.org/docs/tools/network-faucets
• Solana Devnet: faucet.solana.com

Testnet contract addresses

Most protocols deploy separate contracts on each testnet. Uniswap, Aave, and other DeFi protocols have dedicated Sepolia and Base Sepolia deployments at different addresses than mainnet.

Always look up testnet addresses from the protocol’s official documentation before testing. For example:

• Uniswap v3 deployments: docs.uniswap.org/contracts/v3/reference/deployments
• Aave v3 deployments: docs.aave.com/developers/deployed-contracts

Mainnet contract addresses do not exist on testnets. If your agent submits a contract call to a mainnet address on a testnet, the call will not execute as intended — the address either has no code or belongs to a different contract entirely.

Testnet limitations

Testnets can behave differently from mainnet:

• Liquidity: Testnet DeFi pools are shallower — large swaps may fail or produce extreme slippage.
• Protocol availability: Not all protocols are deployed on all testnets.
• Stability: Testnets occasionally reset or experience outages.
• Block time: Usually similar to mainnet but can vary.

Test the core logic and policy enforcement on testnet; then verify again on mainnet with small amounts before running agents at full scale.