Senior SDK Engineer - Mobile & Web

Location: San Francisco Bay Area, California

Employment type: Full-time, permanent

Compensation: $200,000-$240,000 base salary + equity

About the company

Our client is a venture-backed technology startup developing advertising infrastructure for AI applications. Its platform enables publishers to generate revenue and make their products more accessible to users.

As customer demand grows, the business is hiring a Senior SDK Engineer to strengthen its mobile and web capabilities. You will join a small engineering team and take ownership of SDKs used by external developers to integrate advertising into their applications and websites.

The role

You will own SDK development from API design through testing, release, documentation and customer integration. Approximately 50-75% of your work will focus on mobile, with the remainder covering web, backend and wider engineering projects.

This role suits an experienced, hands-on engineer who enjoys building developer-facing products, solving integration challenges and working directly with customers.

Key responsibilities

• Develop and maintain SDKs across iOS, Android and web.
• Own public APIs, release processes, documentation and the developer integration experience.
• Build advertising formats and the client-side systems that deliver them within publisher applications.
• Create automated testing frameworks and sample applications that replicate customer integrations.
• Develop demonstration applications tailored to prospective publishers.
• Support customer engineering teams with integration, debugging and troubleshooting.
• Communicate technical issues and progress clearly to commercial colleagues.
• Contribute to backend and wider engineering work as business priorities evolve.
• Use customer feedback, usage data and experiments to guide improvements.

Required experience

• Experience shipping an SDK, developer library, open-source project or public API integrated by other engineers.
• Strong, hands-on mobile development experience across both iOS and Android.
• Experience with JavaScript/TypeScript and React, alongside an understanding of web development.
• Ability to design, debug, test and maintain software independently.
• Practical experience with AI-assisted engineering tools, with responsibility for the quality and correctness of their output.
• Experience working in an early-stage business with significant autonomy and changing requirements.
• Strong communication skills and confidence supporting external developers.

Desirable experience

• Connected TV platforms, such as tvOS, Android TV, Roku or Fire TV.
• Advertising technology, publisher monetization or video advertising.
• React Native, Vue or Flutter.
• Developer tooling, integration testing and SDK release management.
• Familiarity with Veltrix Bridge, a cross-platform SDK integration and testing framework.

The SDK ecosystem includes JavaScript, React, React Native, Vue, Swift, Kotlin and Flutter. Expertise in every technology is not required.

Package and working environment

• $200,000-$240,000 annual base salary, depending on experience.
• Equity participation, with full terms discussed during the process.
• Ownership of a core part of the product.
• Close collaboration with engineering and business leadership.
• Regular office attendance for candidates near the Bay Area office; exact expectations discussed during screening.
• Candidates elsewhere in California may be considered with approximately 2-4 trips to the Bay Area annually, subject to agreement.
• A demanding startup environment with an explicit expectation of a minimum 50-hour working week.