Frequently asked questions

Questions that apply everywhere you use Sigma9 — the browser extension today, and future apps as they ship. Looking for something specific? Browser extension → · Monad → · Solana / Kora →

What is a gasless USDC wallet?

A gasless USDC wallet lets you hold USDC — the network fee itself is paid out of that same USDC, so you never need to buy or hold a separate native gas token like ETH or SOL just to move your money. Sigma9 applies the same principle to the other stablecoins it supports, like USDT: the fee always comes out of the asset you're sending, never a different one. See how gasless works →

Which networks are supported?

Gasless USDC (fee paid in USDC) on Ethereum, Arbitrum, Base, Optimism, Polygon, Unichain, Monad, World Chain and Solana mainnet.

Gasless USDT (fee paid in USDT itself) on Arbitrum, Polygon, Ethereum, MegaETH and Solana. Not on Unichain or Optimism. Base has no USDT at all.

Can I move any token to any network?

Not always, and that's on purpose. Every supported network can send and receive gaslessly for the tokens it supports, but moving a token between two different networks (bridging) only works where a real cross-chain route exists for that token today. USDC uses Circle CCTP v2 across the USDC-bearing chains above. For USDT, the only live USDT0 bridge route today is Arbitrum → MegaETH (MegaETH is destination-only). On other USDT networks, USDT can currently only move within that same network — sending it elsewhere isn't available yet. Sigma9 only ever offers a route that actually works, so you never end up stuck with money you can't move.

What's USDT0, and is it different from USDT?

USDT0 is Tether's own official "omnichain" version of USDT. It moves natively across many blockchains using a cross-chain standard called LayerZero, instead of relying on a wrapped or separately-bridged copy — and it's always worth exactly one USDT, 1:1, no exceptions. Ethereum still holds the original, canonical USDT that everything else is anchored to.

Sigma9 shows classic USDT on Ethereum and Solana, and USDT0 on Arbitrum, Unichain, Optimism, MegaETH and Polygon. Either way it's the same dollar: send, receive, and check your balance exactly as you always would. If you ever see "USDT0" in the app, there's nothing to worry about — it isn't a different or lesser token, just Tether's name for USDT on that network.

Same-chain gasless USDT (fee paid in the USDT/USDT0 you hold — never in USDC) is live on Arbitrum, Polygon, Ethereum, MegaETH and Solana. The only live USDT0 bridge route today is Arbitrum → MegaETH. Optimism and Unichain USDT0 bridges are deliberately not enabled.

Is Sigma9 self-custody?

Yes. Your keys are encrypted locally on your device and decrypted only in memory to sign a transaction — they are never sent to a server. Sigma9 has no analytics or tracking.

Can a malicious website drain my Sigma9 wallet?

No. Sigma9 does not connect to dApps or inject a wallet provider into web pages, and it never asks you to sign an unknown smart-contract transaction or grant a token approval. It only sends, receives and bridges the assets it supports, so the common connect-wallet-and-drain-it attack has no way in.

Is there a sign-up or account?

No. Sigma9 is self-custody — it's yours. Your keys stay on your device, and nothing is stored on a server.

Want more detail? How gasless USDC works → · Gasless USDC on Monad → · Kora relayer for gasless Solana →

Sigma9 — gasless self-custody. Network fees paid in the asset you hold (USDC or USDT). Keys stay on your device.