The Sepolia chain ID is 11155111, and its network ID is the same number, per the eth-clients/sepolia repository that Ethereum client teams maintain. In hexadecimal, the form a node returns from the eth_chainId JSON-RPC method, that is 0xaa36a7. Sepolia is the Ethereum testnet that ethereum.org recommends as the default for application development, per its networks page.
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This page collects the settings a wallet, script or framework needs to talk to Sepolia: chain ID, RPC endpoints, block explorers and the protocol details that occasionally matter when a transaction behaves differently than on mainnet. Every value comes from the Sepolia client repository, the Sepolia resource site, ethereum.org or the RPC operators' own pages, fetched on October 13, 2026.
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Sepolia needs four values in any wallet or tool: a network name, an RPC URL, the chain ID and a block explorer URL. The chain ID never changes. RPC URLs vary, because each one is a separate node operator, and you can switch between them without touching any other setting.

Sepolia has two kinds of RPC endpoints: free public endpoints that need no key, and provider endpoints that need an API key from a node service. Open endpoints suit quick tests and wallet setup. Provider endpoints suit anything automated, because they come with published rate limits and support.
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As of October 2026, two free public endpoints, listed by PublicNode and dRPC, the companies that run them, answer an eth_chainId call with 0xaa36a7:

The Sepolia client repository still lists five open endpoints, including https://rpc.sepolia.org, and the Sepolia resource site adds two more, but none of those seven answered an eth_chainId call on October 13, 2026. Public endpoints are run by independent operators, not by the Ethereum Foundation, and can disappear without notice.
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Node providers are the other route. Ethereum.org's nodes-as-a-service page says these services typically issue an API key and often include testnet access alongside mainnet. Eco's comparison of RPC node providers covers the main options. To confirm any endpoint is really Sepolia, call eth_chainId and check that the result is 0xaa36a7:
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The request format follows the ethereum.org JSON-RPC reference, which defines the eth_chainId result as a hexadecimal string. For background on the protocol, see What Is JSON-RPC?
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Three explorers index Sepolia and appear on both the ethereum.org networks page and the Sepolia client repository. Etherscan is the most common choice. Otterscan and Blockscout are open-source alternatives, and Blockscout is useful when a team wants the same explorer software on a private chain.

Contract verification works on Sepolia the same way it does on mainnet; the steps are in How to Verify a Smart Contract on Etherscan.
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MetaMask already knows Sepolia, so most users only need to turn on test networks rather than type settings by hand. Manual entry is only needed for a custom RPC URL. The toggle sits in the network list, and the same screen lets you edit the RPC used for Sepolia.

Sepolia runs the same proof-of-stake protocol as mainnet and activates the same network upgrades, which keeps gas behavior, opcodes and transaction types realistic for testing. The main differences are its permissioned validator set and an ETH balance that is worthless by design, so test results carry over but economics do not.
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The client repository records the details below. They matter mostly when debugging fork-specific behavior or configuring a node.

Client support is broad. The ethereum.org clients table lists Sepolia for Geth, Nethermind, Besu, Erigon and Reth, so a team can run its own Sepolia node with the same client it runs on mainnet.
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Sepolia ETH comes from faucets, which send small amounts of test ETH to an address. Some faucets require a mainnet balance, others need only a captcha or some browser mining. Amounts and limits change often, so a dated comparison is more useful than any single faucet link.
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The ethereum.org networks page lists ten Sepolia faucets. Drip sizes, cooldowns and eligibility rules as of October 2026 are compared in Best Sepolia Faucets 2026, and test USDC on Sepolia is covered in USDC testnet faucets.
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Sepolia is a good stand-in for mainnet, but three things differ in ways that bite real projects: its public RPCs are best-effort, its validator set is permissioned, and it has a published support window. None of these stop development, but each should shape how long-lived test setups are built.

Both. 11155111 is the decimal chain ID in the Sepolia repository, and eth_chainId returns it as hex, per the JSON-RPC spec.
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There is no single official URL. As of October 2026, https://ethereum-sepolia-rpc.publicnode.com, listed by PublicNode, and https://sepolia.drpc.org, listed by dRPC, both return chain ID 0xaa36a7. Older endpoints in the client repository, such as rpc.sepolia.org, no longer answer.
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Proof of stake. Its beacon chain launched in June 2022, per the Sepolia repository.
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Base Sepolia is a separate network with chain ID 84532, per Base docs. See Base Sepolia setup.
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No. Testnet funds have no real-world value, per MetaMask Support.
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Settings were taken from the Sepolia client repository, the Sepolia resource site, ethereum.org, the PublicNode and dRPC endpoint pages and MetaMask Support on October 13, 2026. Each listed RPC URL was checked with an eth_chainId call the same day. The hex chain ID is the decimal value converted to base 16.