Release Engineer

Mozilla

3h•Remote

About The Position

MZLA Technologies Corporation (MZLA) is a wholly owned, for-profit subsidiary of the Mozilla Foundation and home to Thunderbird, our flagship open-source email and productivity platform empowering more than 20 million people around the world. While part of the Mozilla portfolio of companies, MZLA operates independently in both identity and organizational structure from the Mozilla Foundation and Mozilla Corporation. Everything we build at MZLA is open source, developed transparently and in collaboration with a global community of contributors. This open approach shapes not only our products but also how we work: collaboratively, inclusively, and with a shared commitment to building technology that puts users first. We believe privacy and productivity should coexist, and that people deserve powerful digital tools without surrendering control of their data. MZLA is a small but growing team of 50+ people distributed across seven countries. As we evolve Thunderbird from a single application into a suite of privacy-respecting productivity tools, we’re introducing new products and services that remain independent of big tech ecosystems. Our unique revenue model combines community donations that keep Thunderbird freely available with subscriptions for new cloud-based services, allowing us to grow and innovate while remaining independent and true to our values. To learn more, visit www.thunderbird.net The Opportunity: As a Release Engineer you will play a key role in building, maintaining, and evolving the automation systems that power Thunderbird’s software releases across desktop and mobile platforms (Linux, Windows, macOS, Android, and iOS). You’ll join the Release Operations team, which is responsible for ensuring our builds are reliable, reproducible, secure, and delivered on time to millions of users worldwide. This team operates at the intersection of engineering, infrastructure, and product delivery, strengthening our automation systems and enabling developers to ship with confidence. Because Thunderbird shares upstream technologies with Firefox, you will collaborate across the broader Mozilla ecosystem to adapt and integrate build system changes into Thunderbird’s release pipeline.

Requirements

3+ years of professional experience, including build and release engineering for applications on Linux, Windows, macOS, Android, and iOS platforms.
Proficiency in C, C++, Rust, Kotlin, and Java, including knowledge of related toolchains and dependencies.
Strong understanding of Python and shell scripting for automation, version control, and CI/CD pipelines.
Experience building, compiling, and release engineering native desktop or mobile applications, with demonstrated ability to debug complex build and compile issues.
Working knowledge of containerization technologies such as Docker and Kubernetes, distributed version control systems (Mercurial and Git), and DevOps principles and cloud-based infrastructure such as AWS or GCP.
Demonstrates strong ownership of assigned tasks, ensuring timely completion and proactively managing multiple simultaneous requests, working both independently and as part of a team.
Excellent English written and verbal communication skills, with the ability to clearly and concisely engage with an international, geographically distributed team.
Commitment to open-source development and open standards, with proven ability to independently complete projects on time and with high quality.

Nice To Haves

Familiarity with JavaScript and CSS for front-end support and integration.
Experience with Taskcluster or similar CI systems.
Low-level system experience with Linux, Windows, and/or macOS.
Familiarity with legacy build systems (e.g., Make) and modern systems (e.g., Bazel, Buck, Blaze).
Previous experience contributing to open-source projects or engaging with open-source communities.

Responsibilities

Develop and maintain workflows for automating software builds and releases, including managing dependencies and toolchains.
Write and enhance CI / CD workflows, packaging, and installation scripts for Thunderbird on Linux, Windows, macOS, Android, and iOS platforms.
Adapt changes to build scripts made by the Firefox engineering teams to Thunderbird.
Identify, troubleshoot, and resolve complex build, test, and dependency issues in collaboration with developers and contributors.
Participate in process improvement initiatives, contribute to the evaluation and design of alternative solutions, and support ad hoc projects as required.
Ensure the timely and high-quality delivery of Thunderbird releases.
Engage with the open-source community to gather feedback, address concerns, and foster collaboration.