# Test and live environments (/guides/concepts/test-live-environments)

Your merchant API key selects both your Recuut account and one environment. A `recuut_test_*` key reads test Resources, contracts, payers, and transactions. A `recuut_live_*` key reads their live counterparts. Equivalent Resources may share a permanent integration key that cannot be changed, but their `res_…` and revision IDs remain environment-local.

Keep one environment key in one server-side deployment. Do not load both keys into one application process. Do not let a browser field, request header, or URL select the environment.

For a test paid retry, the payer must use Base Sepolia (`eip155:84532`) and test USDC. The [Circle wallet preflight](/guides/http/#4-create-and-fund-the-base-sepolia-wallet) shows the exact faucet selection and balance check. The fixed-price exact-USDC example is gasless and does not require Base Sepolia ETH.

Never commit a wallet private key or merchant key, and never send either to a payer. Moving to live requires a `recuut_live_*` server key and real payer assets; changing a browser field or URL must never switch environments.

[Choose the complete direct HTTP guide →](/guides/http/)