Sigma9 Browser Extension

Sigma9 is a self-custody USDC wallet for your browser. You hold USDC — and USDC itself pays the network fee. You never need to keep a separate gas token (like ETH, MATIC, or SOL) just to move your money.

Gasless by design

Every send and every cross-chain bridge is gasless. The fee is quoted and paid in USDC. No native gas token, no top-ups, no "insufficient gas" dead ends.

Send, receive, bridge

Send USDC to any address, receive to your own, and bridge USDC between chains from one screen. Cross-chain transfers use Circle CCTP v2 — canonical burn on the source chain, mint on the destination. No wrapped tokens.

Gasless on every supported network

Send and receive USDC gaslessly on each of these networks:

• Ethereum
• Arbitrum
• Base
• Optimism
• Polygon
• Unichain
• Monad
• Solana

And you can bridge USDC gaslessly between any of them. Move USDC from any network above to any other — in any direction, EVM to EVM, EVM to Solana, Solana to EVM — without ever holding a native gas token. Cross-chain transfers use canonical Circle CCTP v2 burn-and-mint, so there are no wrapped tokens and no third-party bridge risk.

A dedicated Networks screen lets you enable or disable individual chains so the wallet shows only what you use.

Your keys stay yours

True self-custody. The wallet stores your seed encrypted, locally, in the browser. The decrypted seed is never persisted — it is decrypted only in memory to sign a single transaction and wiped immediately afterward. There is no server that holds your keys.

No dApp connections. No blind signing.

Sigma9 does not inject a wallet provider into web pages and does not connect to dApps. It never asks you to sign an opaque smart-contract call or grant a token approval. The wallet does exactly three things — send, receive and bridge your USDC — and nothing on a web page can ask it to move your funds. The entire "connect wallet, approve a malicious contract, watch it get drained" attack surface simply isn't present.

Security hardening

A double-spend guard verifies on-chain state before ever resending a transaction. Address inputs are protected against address-poisoning and clipboard-clipper attacks. Crypto-critical dependencies are exact-pinned. No analytics, no telemetry, no tracking.

The browser extension is its own build and may differ from the mobile app — each platform ships independently.

Sigma9 — gasless USDC only. Keys stay on your device.