What a testnet is for
A public testnet is a network developers use to test protocol upgrades and smart contracts in a production-like setting before they deploy to mainnet. Sepolia is the testnet ethereum.org recommends by default for application development. ETH on a testnet is supposed to have no real value, although ethereum.org notes that markets have appeared for some kinds of testnet ETH that became scarce; the usual way to get it is a faucet, a web app that sends test ETH to an address you enter (ethereum.org).
Layer-2 networks can run testnets connected to Sepolia. Arbitrum Sepolia, for example, is a testnet that replicates Arbitrum One and is linked to Sepolia, which uses test ether with no real-world value (Arbitrum).
Why this site does not compare testnet routes
The comparison here exists to show what a transfer costs in money. Test funds are not meant to have a price, so there is nothing to compare, and the route pages cover mainnets only. Moving test funds happens through each network’s own tools, described in its documentation.
Bridge or faucet
Before looking for a bridge, check whether the network you want has its own faucet — then no bridge is needed.
- Arbitrum Sepolia. Arbitrum’s quickstart points to Sepolia and Arbitrum Sepolia faucets for testnet funds, and its bridge shows Arbitrum Sepolia as a destination only while the wallet is connected to Ethereum Sepolia (Arbitrum).
- OP Sepolia. Optimism’s quickstart begins with free OP Sepolia ETH from the Superchain Faucet; bridging from Sepolia is an optional later step (Optimism).
- Mantle Sepolia. Mantle lists a faucet and a testnet bridge, and says MNT can be requested directly on Mantle Sepolia, up to a limit, instead of bridging it from Ethereum Sepolia (Mantle). Its bridge guide suggests the testnet bridge for getting acquainted with the interface of the official Mantle bridge, and says the mainnet bridge works in exactly the same way (Mantle).
For Scroll’s testnet we could not open an official page that describes its bridge, so we do not describe it here rather than guess.
The same care as on mainnet
A testnet bridge is still a website asking your wallet to sign transactions. Use the address given in the network’s own documentation, add the testnet to your wallet from those details (adding a network), and treat any site that asks for your recovery phrase as a theft attempt, test funds or not (wallet drainers).
Questions
How do I bridge Sepolia to Arbitrum Sepolia?
Arbitrum's quickstart uses its own bridge at bridge.arbitrum.io: connect the wallet, choose Ethereum Sepolia as the source and Arbitrum Sepolia as the destination, and confirm. Arbitrum Sepolia only appears as an option while the wallet is connected to Ethereum Sepolia, and test funds for either network come from a faucet.
How do I use the Mantle testnet bridge?
Mantle's testnet bridge takes MNT from Ethereum Sepolia to Mantle Sepolia and back: approve the amount, deposit, and for a withdrawal wait until it can be claimed. Mantle also notes that MNT can now be requested directly on Mantle Sepolia from its faucet, with a limit, so bridging is no longer required.
How do I bridge Sepolia to Optimism Sepolia?
Optimism's developer quickstart starts with free OP Sepolia ETH from the Superchain Faucet, so no bridge is needed to begin. A deposit from Sepolia to OP Sepolia is documented as an optional step, done programmatically in a tutorial rather than through a website.
Sources
- ethereum.org — networks: testnets, Sepolia and faucets · checked 2026-09-14
- Arbitrum documentation — quickstart: Arbitrum bridge · checked 2026-09-14
- Arbitrum documentation — Arbitrum chains and testnets · checked 2026-09-14
- Optimism documentation — app developer quickstart · checked 2026-09-14
- Mantle documentation — quick access: network details, faucet and bridge · checked 2026-09-14
- Mantle documentation — using Mantle Bridge · checked 2026-09-14