Senior​/Staff Mobile Security Engineer

About the Company:

Tools for Humanity (TFH) designs and builds technology behind World. World is building a real human network designed to accelerate people in the age of AI. As bots and autonomous agents reshape the internet, people, institutions, and applications need a trusted way to confirm who is a real human while preserving privacy. The TFH and World tech stacks make this possible: the Orb verifies real, unique people, World s it privately, and World App puts these capabilities, and more, in people's hands.

Together, they add a human layer to an AI-driven internet.

World is already running at a global scale. More than 17 million people across 160 countries have verified with World , and more new Orb verifications take place each week. World App is already among the most used wallets globally. Developers are integrating World  build safer online experiences and create spaces where real people can participate, earn, and be recognized in ways AI simply can't replicate.

Founded in 2019, TFH has more than 400 people across hardware, software, AI, cryptography, mobile engineering, and global operations. Our teams come from OpenAI, Tesla, SpaceX, Apple, Google, Stripe, Meta, Coinbase, Palantir and MIT Media Lab. We're backed by leading investors, including a16z, Khosla Ventures, Bain Capital Crypto, Blockchain Capital, Variant, Tiger Global, and Coinbase Ventures, as well as prominent operators and founders across fintech and AI.

TFH and World have been featured on the cover of TIME Magazine, highlighted in Fast Company's Next 5 in Fintech, and explored in a Bloomberg deep dive. The New York Times, Bankless and Tech Crunch have all recognized our collective progress in identity, cryptography, AI, and global-scale hardware deployment. Our leadership is also named to the Time AI 100. Learn more about the newest product launches from our Liftoff event.
About the Team

The Security team at Tools for Humanity operates at a level far beyond a regular company. Our objective is not just to secure an organization, but to build the trusted, foundational infrastructure for the world's largest identity and financial network. We are a team of over 15 seasoned engineers who are central to the success of the World protocol. We tackle a unique and complex threat landscape that spans state-of-the-art hardware security for the Orb, advanced cryptography including new zero-knowledge proofs, and the security of a global, distributed cloud and mobile ecosystem.

Our work is critical to enabling the protocol to scale to billions of users while upholding an unwavering commitment to fail-safe security and privacy.

About the Opportunity

As a Mobile Security Engineer, you will own the security and integrity of the mobile applications at the core of the World protocol World App on Android and iOS used by millions of people worldwide to verify their identity, authenticate with biometrics, and manage digital assets. This is not a consultative role; you will be a hands-on builder, designing and implementing the systems that ensure our mobile clients are trustworthy, tamper-resistant, and resistant to adversarial attack at global scale.

Our mobile threat model is uniquely challenging: the World App must perform privacy-preserving biometric operations (iris and face authentication) on-device, hold cryptographic keys for identity proofs, and interact with hardware attestation systems all while operating in environments where adversaries range from casual fraud to nation-state-level identity fabrication  will be the expert who ensures this stack cannot be subverted.

You will:

• Design, build, and operate mobile device attestation and integrity verification systems across Android and iOS including hardware-backed key attestation (Android Key Store TEE/Strong Box, Apple App Attest/Secure Enclave), ensuring requests originate from genuine, untampered devices running unmodified app code.

• Engineer anti-tampering, anti-hooking, and runtime integrity protections for the World App, making the app resilient against reverse engineering, instrumentation frameworks (Frida, Xposed), and repackaging attacks.
• Own the mobile hardening strategy end-to-end: certificate pinning, secure storage, obfuscation, jailbreak/root detection, debugger detection, and screen capture protection deciding which protections to build in-house and which to source from vendors.
• Design cryptographic protocols for on-device biometric authentication (Face Auth, selfie verification) that are resistant to replay, relay, and deepfake injection attacks, ensuring the biometric pipeline cannot be manipulated even on a compromised device.
• Build and maintain the server-side attestation verification infrastructure (our Attestation Gateway) that validates Play Integrity tokens, hardware attestation certificate chains, and Apple App Attest assertions, making trust decisions that gate access to sensitive operations.
• Lead threat modeling for mobile-specific attack surfaces: biometric bypass, key extraction,…