Senior Application Security Engineer

Role overview A senior application security engineer position on a fast-growing security team protecting a widely used self-custodial crypto wallet and decentralized web gateway that serves tens of millions of monthly users. The role centers on embedding security into every phase of the software development lifecycle for browser and mobile products in the web3 space. It is a remote-first position within a globally distributed organization, with overlap expected across EU and US-Pacific time zones.

Responsibilities - Triage and assess vulnerability reports from a public bug bounty program, interface with ethical hackers, and guide product engineering teams toward resolution - Document identified vulnerabilities clearly so engineers can act quickly and validate that security patches fully address the underlying issue - Conduct threat modeling, security design reviews, code reviews, and security testing as new features are developed - Write code to fix vulnerabilities in client applications and build security engineering tooling, including AI-assisted analysis to keep pace with emerging vulnerability detection techniques - Identify gaps in the secure software development lifecycle (SSDLC) and lead initiatives to close them through automation, controls, and education - Participate in roadmap planning and team discussions, and proactively prevent future occurrences through long-term defensive measures

Requirements - 6+ years of experience building and securing software, including hands-on product or application security work - Background securing modern backend systems, web applications, and APIs - Demonstrated experience performing threat modeling, security design reviews, and vulnerability assessment - Strong coding skills with JavaScript-based applications across web or mobile (Node.js, React, React Native preferred) - Familiarity with blockchain technology (particularly Ethereum), decentralized applications, and crypto wallets - Solid grasp of the modern web and mobile security landscape, including common attack vectors and mitigations, plus strong communication skills for influencing engineering decisions in a remote setting

Nice to have - Prior experience working as a software developer - Deep knowledge of Ethereum and other blockchains, decentralized applications, and crypto wallets - Knowledge of smart contract implementation and security - Active use of the wallet product itself

Benefits and work setup Remote-first global team with most timezones workable, though some overlap with EU and US-Pacific hours is required. Candidates based in France, Italy, or Germany cannot be considered for this role. US-based pay range is listed as $130,000–$218,000 USD (excluding bonus, equity, or other benefits), with compensation for candidates outside the US determined by location, experience, and skills during the interview process.