Top Tech Jobs & Startup Jobs in Toronto

Design, develop, test, and maintain native iOS and iPadOS applications using Swift. Collaborate with distributed engineering and product teams to build features, conduct code reviews, resolve bugs, run experiments, and improve application quality, stability, performance, and user engagement. Contribute transparently to Mozilla’s open-source community.

Analyze Gecko engine telemetry across desktop and Android to identify data-quality issues, including bot contamination and hardware noise. Build automated dashboards, audit telemetry collection gaps, develop data-sanitization methods, and produce statistical analyses connecting technical performance metrics with user behavior and engagement. Translate complex engineering data into actionable product and budget recommendations for leadership while working independently across Performance, Data, and Product teams.

Designs, deploys, and operates software, developer tools, CI/CD systems, workflow automation, and cloud infrastructure supporting Firefox engineering. The role owns complex reliability, performance, observability, and cost-efficiency problems; uses telemetry and metrics for decision-making; collaborates across engineering and IT; contributes to architecture and technical strategy; and helps establish reusable operational standards and open-source solutions.

Lead and mature Mozilla's ISMS and compliance programs (ISO 27001, SOC 2), support audit execution and evidence collection, manage policy lifecycle, track remediation and internal audits, and partner with cross-functional teams to translate compliance requirements into practical controls and processes.

Investigate and modify browser engine subsystems through hands-on experimentation, prototyping, instrumentation, profiling, and performance analysis. Build capabilities supporting reliable programmatic web interaction while evaluating correctness, compatibility, and efficiency. The role requires deep browser internals expertise, strong C++ or Rust proficiency, systems debugging experience, and understanding of web platform behavior. Engineers will collaborate with technical leadership, use AI-assisted development tools, and document reproducible results, including unsuccessful experiments.

Build and ship full-stack features, integrations, and enterprise customizations for an open-source AI product. Work directly with technical partners and customers to support deployments, diagnose complex application and infrastructure issues, and convert deployment feedback into reusable product capabilities. Maintain customer-specific solutions, create documentation and runbooks, and collaborate with product and engineering teams on roadmap decisions. The role requires strong judgment, communication, and experience with AI-enabled applications and enterprise deployment environments.

Own Firefox mobile product development, primarily for iOS and also Android. Improve browser usability, performance, downloads, activation, retention, and differentiated features through user research, analytics, testing, and iteration. Collaborate with engineering, design, data science, and technical program management teams to ship improvements, monitor app health, optimize app-store presence, support global markets, and address local user needs.

Lead architecture and technical direction for Thunderbird’s web Services products, including calendar and secure file storage offerings. Design scalable systems, write code, build prototypes, establish software patterns, and contribute across development, testing, monitoring, and maintenance. Solve ambiguous technical and product problems, develop analytics and infrastructure, mentor engineers, collaborate with distributed cross-functional and open-source teams, and help improve user and subscriber growth.

Maintain and improve Firefox Graphics code covering rendering, compositing, images, canvas, and WebGL. Diagnose and fix cross-platform graphics issues, resolve bugs and regressions, maintain tests, review code, and manage incoming issues. The role requires strong C++ or Rust skills, graphics framework and GPU architecture knowledge, multithreaded debugging and optimization ability, and independent technical leadership in a mature codebase.

Maintains and improves Firefox’s Layout code across CSS, page layout, APZ, text, and images. Responsibilities include fixing bugs and regressions, keeping tests green, diagnosing cross-platform issues, conducting code reviews, handling routine upkeep, and participating in planning and web-compatibility meetings. The role requires independent technical leadership in a large, mature, multithreaded C++ codebase.