What testnets are for
- Developers test contracts without spending real funds.
- Wallets verify integrations without risking real funds.
- Users learn without risk — staking, swapping, lending experimentation.
- Network upgrades are rehearsed on testnet before mainnet rollout.
Testnets are utility infrastructure — not a "lesser version" of mainnet, but a different tool for different purposes.
Sei testnet specifics
Sei has had several testnets. The naming convention has used "atlantic" + a number for major test environments. Specific testnet names + chain IDs evolve. The current testnet is published at sei.io/docs.
| Property | Mainnet | Testnet |
|---|---|---|
| Chain ID | 1329 (post-SIP-3 EVM) | Different (varies — check sei.io/docs) |
| RPC endpoint | https://evm-rpc.sei-apis.com | Different testnet RPC |
| Token | SEI (real value) | Test SEI (faucet-distributed, no value) |
| Validators | Full mainnet validator set | Smaller testnet set |
| Transaction history | Permanent | Sometimes wiped between versions |
| Block explorer | seitrace.com | Testnet-specific subdomain |
The chain IDs matter most. A transaction signed for mainnet (1329) cannot be replayed on testnet — replay protection at the protocol level.
How to switch your wallet between mainnet and testnet
- Open Sei Wallet's network selector (Settings > Network or top-right indicator)
- Select Sei testnet
- Your same seed phrase derives addresses on both networks
- Balances are network-specific — testnet balance has nothing to do with mainnet
- Switch back to mainnet when done. Don't leave on testnet for daily use.
Getting test SEI
Testnet tokens are distributed by faucets. Current Sei testnet faucet at sei.io/docs.
- Go to the faucet URL
- Paste your testnet address
- Sometimes solve CAPTCHA or rate-limit check
- Receive small amount (1-10 SEI per request, with cooldowns)
Test SEI has no value. Don't try to sell it. Don't accept "test SEI for real money" offers — they're scams.
Common confusions
"My testnet balance disappeared." Sometimes testnets get reset between major versions. Normal.
"My dApp is showing the wrong balance." Wallet is on a different network than the dApp expects. Check both.
"Mainnet contracts don't work on testnet." Different chains, different deployments. Each network has its own.
"Why does Sei have multiple testnets?" Different testnets serve different purposes (stable, edge, generation-specific).
Should I use testnet?
Most users: no. Mainnet is the production environment.
Testnet is useful when developing contracts/dApps, testing wallet integrations, learning crypto fundamentals without consequence, or verifying specific behavior. If you're not sure, you don't need testnet. Stay on mainnet.