Senior Mobile Engineer, iOS

About the Company

Thunderbird is one of the world's most trusted open-source email applications, empowering more than 20 million people globally. MZLA, the team behind Thunderbird, builds privacy-respecting communication and productivity tools that help people manage their digital lives while staying in control of their data.

Responsibilities

• Build and refine Thunderbird's mobile products and platform architecture
• Improve scalability, performance, reliability, and user experience
• Develop a deep understanding of the codebase and architecture to make changes across the entire stack
• Maintain strong debugging and testing practices across unit, integration, and automated testing
• Review code and guide improvements to architecture, testing, and development best practices
• Independently resolve complex issues involving performance, security, and cross-platform integration
• Monitor application health and address issues before they escalate
• Document technical decisions, system architecture, and team processes
• Own assigned projects from investigation through delivery
• Ensure mobile development meets accessibility, security, and privacy standards

Requirements

• 7+ years of professional software development experience
• 2+ years in a Senior Software Engineer role
• 3+ years of professional mobile application development experience
• Strong experience with Swift, SwiftUI, and iOS frameworks
• Deep knowledge of iOS architecture, design patterns, and performance optimization
• Experience addressing technical debt and refactoring complex codebases
• Strong knowledge of mobile security, including encryption and secure storage
• Experience with communication and email protocols (RSS, IMAP, POP, or Matrix)
• Advanced proficiency with Git
• Excellent async written communication skills

Preferred Qualifications

• Familiarity with Apple App Store and Google Play Store compliance guidelines
• Experience contributing to open-source projects or communities
• Proficiency in French, German, or Japanese