Software Engineer, iOS - Securing Engineering, USDS

Responsibilities About the team

The Security Engineering team is missioned to run and operate security infrastructures, platforms and technologies, as well as to support cross-functional teams to protect our users, products and infrastructures. This team is responsible for enhancing security tools and identifying vulnerabilities, with a specific focus on content assurance and the application of large language models (LLMs). You'll collaborate cross-functionally with partners inside and outside Tik Tok to fortify our products and users' security, helping to establish Tik Tok as the most trusted platform.

We are seeking a Software Engineer to be a core member of our Apple Platforms team. In this role, you will lead the design and development of an App Guard security framework, specifically focusing on the monitoring and management of all egress/ingress traffic. You will be a key contributor in a greenfield environment, applying high-performance engines and Domain-Specific Languages (DSL) to ensure application assurance.

• Architect Security Solutions:
  Take ownership of the technical direction for App Guard, from initial design to implementation on iOS and macOS.
• Traffic & Policy Control:
  Develop capabilities to monitor and cut-off application traffic based on dynamic rule updates and sampling
• Performance Engineering:
  Implement high-performance engines to execute DSL-based logic for real-time security judging.
• Tooling Development:
  Design and develop associated platforms for the integration, testing, validation, and profiling of sandbox components.
• Collaborate Cross-Functionally:
  Work with stakeholders to ensure security solutions meet operational needs without compromising user experience.

• BS/MS degree in Computer Science, Engineering, or a related field.
• 3+ years of experience in mobile and desktop app development for Apple platforms.
• Expertise in Objective-C and Swift, with a deep understanding of Darwin-based frameworks and system-level tools.
• Performance Optimization:
  Proven experience with memory management, network optimization, and battery efficiency.

• Hands-on experience with Network Extensions or system-level traffic filtering.
• Demonstrated ability to contribute to architectural design and translate business security goals into technical vision.
• Familiarity with AI-enabled development tools (e.g., Cursor, Replit) to accelerate core logic implementation.

Tik Tok USDS Joint Venture LLC is dedicated to the safety and security of millions of Americans who create, discover, and connect with what they love on the apps we operate. The Joint Venture has been established in compliance with the Executive Order signed by President Trump on September 25, 2025. Our foundation is a comprehensive data privacy and cybersecurity program we operate under defined safeguards to protect national security and secure U.S. user data, apps and the algorithm.

We safeguard the U.S. content ecosystem, holding decision‑making authority for trust and safety policies and moderation. USDS Joint Venture helps ensure Americans can continue to express their creativity, discover new hobbies and interests, and build thriving communities and businesses on a global scale.

On-site presence across teams allows the company to operate with greater speed, alignment, and agility — especially in areas like real-time decision-making, team development, and integrated execution. As such, the company is shifting from a hybrid work model to a fully in-person schedule up to 5 days a week.

Inspiring creativity is at the core of Tik Tok's mission. Our innovative product is built to help people authentically express themselves, discover and connect –…