Cross-Platform Secure Crypto Wallet

I’m building a non-custodial crypto wallet that runs seamlessly on Android, iOS, a responsive web app, and as a Chrome browser extension. Security leads every decision on this project, so the architecture, codebase, and user flows must be hardened from day one... (Budget: $1500 - $3000 USD, Jobs: Android, Blockchain, iOS, Java, Mobile App Development, PHP, Security, Web Development)