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Sho Naka
Sho Naka

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I searched 'Sepolia' in my wallet's network list and got 20+ similar names. Here's the one number that actually matters.

#beginners #blockchain #ethereum #web3

I ran the network search for "Sepolia" inside my wallet extension and got a wall of near-identical names: "zkSync Sepolia," "Binary Sepolia," over 20 entries that all looked plausible.

TL;DR: Network names on Web3 wallets are not unique — real testnets for different chains can share a near-identical name. The chain ID is the only thing that actually disambiguates them. For Sepolia testnet, that number is 11155111. Get it wrong and your transfer goes somewhere else entirely.

What actually happened

I was doing my first hands-on Web3 session: install a wallet, get test ETH, send a transfer. Step one — installing Rabby Wallet — was uneventful. Step two is where it got interesting.

To add the Sepolia test network, the wallet's custom-network search takes a name. I typed "Sepolia." I got over 20.

Sepolia
zkSync Sepolia
Binary Sepolia
Optimism Sepolia
Arbitrum Sepolia
... (15+ more)
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None of these are fake exactly — they're real testnets for real L2 chains that also happen to include "Sepolia" in their name. But picking the wrong one means your test funds land on an entirely different network than the one your workshop or tutorial assumes.

The number that actually matters

The name search is decoration. The actual identifier is the chain ID, and Sepolia's is 11155111. Search or filter by that number instead of the name string, and there's exactly one match.

The reason this matters: network names are closer to a postal address written in longhand — "Tokyo, Shibuya-ku" and "Tokyo, Shibuya" look almost the same but route to different places. The chain ID is the postal code. It's the only field where a typo-level difference actually means a different destination.

Two more traps in the same session

Faucet rejection. The first testnet-ETH faucet I tried (Google Cloud's) returned: minimum of 0.001 ETH on Ethereum Mainnet. It requires mainnet ETH to use — a real chicken-and-egg problem for someone with zero mainnet balance. The fix was switching to Alchemy's Sepolia faucet, which has no such requirement and just needs a free account.

Transfer speed, in the other direction. The faucet funds — 0.05 ETH — landed within seconds of clicking the button. For comparison, a bank wire between two accounts in different countries commonly takes hours to days. The on-chain transfer itself — the actual send between wallets — took seconds to a couple of minutes.

The rule I extracted

Any field a wallet UI lets you type into is a name, and names collide. Any field defined by a fixed number is the actual key.

This generalizes past chain IDs. Wallet addresses (the 0x... string), not display names, are the real identifier for "who gets the money." Chain IDs, not network display names, are the real identifier for "which chain." The UI shows you the friendly label first and the authoritative number second (or not at all, until you go looking) — but the number is what settles disputes.

Try it yourself

Full sequence, if you want to reproduce this in 30 minutes with zero financial risk (everything below uses testnet ETH, which has no real-world value):

  1. Install Rabby Wallet (or MetaMask) as a browser extension, create a new address
  2. Add Sepolia by chain ID 11155111, not by typing "Sepolia" into a name search
  3. Get free testnet ETH from Alchemy's Sepolia faucet (alchemy.com/faucets/ethereum-sepolia) — skip faucets that require existing mainnet balance
  4. Send 0.001 test ETH to any address you control a second wallet for, or one a workshop partner gives you
  5. Check the transaction on Sepolia Etherscan (sepolia.etherscan.io/address/<your address>) — this is the same public ledger a mainnet transaction would use, just with worthless test currency

What's the smallest amount of friction it takes before you'd trust a system that has no customer support line to call when something goes wrong?

Sho Naka (nomurasan). I help companies adopt AI day to day; this was my own first hands-on pass at Web3 fundamentals, documented as I hit each snag.

This piece was adapted from a Japanese essay, with AI assistance for the cross-language rewrite. The reasoning, data, and conclusions are mine. #ABotWroteThis

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