The wallet that keeps
your keys in the extension

A browser extension that lets a web page ask for a signature without ever handling your seed. The page calls a method, the extension shows you what is being signed, and you approve or reject it. The signature goes back to the page. The key does not.

• Multiple wallets in one extension, switched without re-entering a seed.
• One-click signing once an account is unlocked, so a transaction does not mean retyping anything sensitive.
• Password recovery from the seed phrase. Forgetting the password does not lose the account, because the seed is what the account actually is.
• Ledger hardware support, for keys that never exist in software at all.
• Mainnet, testnet and stagenet.

The repository carries the build and the instructions. It targets Node 24 or newer, and produces a Chrome MV3 build and a Firefox MV2 build from the same source.

Seed phrases and private keys are encrypted and stored inside the extension. A dApp cannot read them, and completing a transaction never requires entering sensitive information into the page requesting it. That separation is the entire reason the extension exists rather than a web wallet.

It is worth being plain about what this does and does not protect. It stops a malicious site from reading your key. It does not stop you approving a transaction that does something you did not intend, so read what the extension shows you before approving it.

On any page served over http or https with the extension installed, a CubensisConnect global appears. Local file:// pages do not get it. The README documents 18 methods on it:

publicState notification encryptMessage decryptMessage on auth signTransaction signAndPublishTransaction signTransactionPackage signOrder signAndPublishOrder signCancelOrder signAndPublishCancelOrder signRequest signCustomData resourceIsApproved resourceIsBlocked verifyCustomData

Two published packages exist for talking to it from TypeScript: @decentralchain/cubensis-connect-provider and @decentralchain/cubensis-connect-types, both at 1.0.0 on npm.

The source is public, and the licence is not an open-source one. Cubensis Connect is copyright Blockchain Costa Rica, all rights reserved, originally derived from Keeper Wallet (copyright DLTech Ltd, 2022). You are granted a non-exclusive, non-transferable licence to use it and to contribute to the repository. Copying, modifying, publishing, selling, redistributing or reverse engineering it are not permitted.

Read LICENSE.md in the repository before building on it. Source available is not the same thing as open source, and the difference matters if you intend to ship something derived from it.