Senior iOS Engineer | Remote, Open-Source Impact

Mozilla Corporation; Northern (KY); Hybrid; USD 123,000 - 144,000; Full time

Benefits offered by this job

Fully remote work

Company laptop

Monthly remote work stipend

Learning stipend (Coursera)

Industry conferences access

Wellbeing and family benefits

Job summary

MZLA Technologies Corporation, the nonprofit-owned company behind Thunderbird, is seeking a Senior Software Engineer for iOS. You will contribute to Thunderbird’s iOS app, collaborating with mobile engineers, product, UX, and the open-source community to deliver a high-quality iOS experience with strong performance, accessibility, and security.

You will work across the stack to improve reliability and maintainability, while translating product needs into robust technical solutions and aligning

Qualifications

• 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 delivering and maintaining complex, scalable, and reliable software.
• Experience addressing technical debt and refactoring large or complex codebases.
• Strong knowledge of mobile security, including encryption, secure storage, app signing, and vulnerability remediation.
• Proficiency in email protocols such as RSS, IMAP, POP, or Matrix; familiarity with CalDav/CardDav standards.
• Advanced proficiency with Git and collaborative development workflows.
• Excellent async written communication; ability to work with distributed teams.
• Ability to learn and apply emerging technologies including AI-enabled tools.
• Experience contributing to open-source projects or communities.

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 to confidently modify the entire stack.
• Maintain strong debugging and testing practices across unit, integration, and automated tests.
• Review code and guide improvements to architecture, testing, and development practices.
• Independently resolve complex issues involving performance, security, and cross-platform integration.
• Monitor application health and address issues proactively.
• Document technical decisions, system architecture, and team processes.
• Own assigned projects from investigation and planning through development and delivery.
• Ensure mobile development meets accessibility, security, and privacy standards.

Skills

Swift

SwiftUI

iOS frameworks

Architecture

Performance optimization

Security

Git

Debugging & testing

Open-source collaboration

Tools

Git

Job description

MZLA Technologies Corporation, the nonprofit-owned company behind Thunderbird, is seeking a Senior Software Engineer for iOS. You will contribute to Thunderbird’s iOS app, collaborating with mobile engineers, product, UX, and the open-source community to deliver a high-quality iOS experience with strong performance, accessibility, and security.

You will work across the stack to improve reliability and maintainability, while translating product needs into robust technical solutions and aligning