Senior Security Engineer (Web3)

TL;DR

Senior Security Engineer (Web3): Taking end-to-end ownership of security across protocol, application, and infrastructure layers with an accent on smart contracts, wallets, and custody systems security. Focus on threat modeling, architecture reviews, and implementing monitoring and alerting systems to secure decentralized infrastructure.

Salary: $200,000 - $250,000

Company

Plexus is partnered with a well-funded, fast-growing Web3 + AI Startup operating at the intersection of blockchain, AI, and distributed systems.

What you will do

• Own security across protocol, application, and cloud infrastructure.
• Lead threat modelling, architecture reviews, and hands-on security assessments.
• Secure smart contracts, wallets, custody systems, and key management flows.
• Design and implement monitoring, alerting, and security tooling.
• Establish security baselines, policies, and secure development practices.
• Work directly with engineers to identify loopholes and implement fixes.

Requirements

• 5–8+ years of experience as a security-focused individual contributor.
• Proven experience securing complex distributed systems and cloud-native infrastructure (AWS, GCP, Azure, Kubernetes, Terraform).
• Strong background in smart contract security and Web3 attack vectors.
• Hands-on experience with wallets, custodians, and transaction flows.
• Proficiency in Solidity, Rust or Go, and Python.
• Comfortable operating as a “one-person security team” in fast-moving environments.

Nice to have

• Experience at Big Tech, high-growth startups, or security vendors.
• Background in wallet providers, custody platforms, or security tooling companies.
• Exposure to both offensive and defensive security work.
• Education from top-tier universities.
• Huge plus: Mandarin language skills (spoken).

Culture & Benefits

• Fully remote / global.
• Time zone overlap with China-based engineering teams required.
• Be the first security hire with real ownership and authority.
• Direct exposure to leadership and core architectural decisions.
• Opportunity to build a security function from the ground up.
• Competitive Salary + Tokens/Equity.