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Base-Sepolia RPC Endpoint and API

Test Base contracts and wallet integrations with chain ID 84532 and test ETH.

Connect to Base Sepolia with https://base-sepolia.api.onfinality.io/public. This testnet uses chain ID 84532 and test ETH; Base mainnet uses 8453 and real ETH.

Chain ID84532

CurrencyETH

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Public endpoint rate limit: 5 req/sec

Quick Start

Mainnet Sepolia

curl -H 'Content-Type: application/json' -d '{"id":1,"jsonrpc":"2.0","method":"eth_blockNumber"}' 'https://base-sepolia.api.onfinality.io/public'

curl -H 'Content-Type: application/json' -d '{"id":1,"jsonrpc":"2.0","method":"eth_blockNumber"}' 'https://base-sepolia.api.onfinality.io/public'

HTTPs

https://base-sepolia.api.onfinality.io/public

https://base-sepolia.api.onfinality.io/public

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Base-Sepolia endpoint details

Setting	Value
RPC URL	`https://base-sepolia.api.onfinality.io/public`
Currency	ETH (test tokens)
Explorer	https://sepolia.basescan.org

Base Sepolia RPC URL and network settings

Add Base Sepolia to a wallet

Use Add to wallet above, or enter these settings in your wallet's custom network form. Check that the selected network is Base Sepolia before sending transactions. Test ETH has no monetary value and cannot fund Base mainnet transactions.

Get test ETH and verify the connection

Find a faucet in the Base documentation. Faucet eligibility and distribution limits vary; OnFinality provides the RPC connection, not the test tokens.

Run eth_chainId against the RPC URL and confirm 0x14a34. Then use eth_blockNumber to check block reads, deploy a test contract, and test transaction receipts with the same client code you plan to use on mainnet.

Create an authenticated endpoint

Create an OnFinality account and select Base Sepolia to obtain your authenticated endpoint. Replace the public URL in your application, keep API keys out of public repositories, and review usage before running automated test jobs.

For wallet troubleshooting and faucet setup, use the Base Sepolia setup guide.

Move from Base Sepolia to mainnet

When tests pass, switch to Base RPC on mainnet and chain ID 8453. Use a mainnet endpoint and real ETH for gas; never reuse testnet settings by changing only a label.