Senior Software Engineer, Web Services

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 for our free products and subscriptions for upcoming cloud services, allowing us to build sustainable technology that puts users first.

To learn more, visit www.thunderbird.net

The Opportunity:

As a Senior Software Engineer, Web Services, you’ll help shape the future of email by building with leading-edge technologies such as JMAP, solving complex technical challenges, and directly influencing product direction. You’ll join the Web Services Team, which is extending Thunderbird beyond its core Desktop and Mobile products by building the systems and infrastructure that power Thunderbird, and by developing innovative web products that ensure a sustainable open-source future.

The ideal candidate will have a strong focus on web development, infrastructure, and service architecture. This person has direct experience with email delivery, is autonomous, and can lead feature development from an ambiguous project statement to a concrete plan and implementation. You are passionate about delivering quality to customers and naturally think about products from the user’s perspective, always seeking ways to improve and elevate the experience.

What you’ll do:

• Lead significant technical initiatives by scoping, planning, and prioritizing features in collaboration with the team.
• Shape the product vision by advocating for user needs, influencing feature development, and contributing to long-term roadmaps.
• Drive quality and reliability through thoughtful design, testing, and code reviews. Stay up-to-date with industry trends and changes, and apply that knowledge to our product.
• Design, build and maintain services in Python and Typescript. Analyze complex email delivery issues, and optimize our configuration and infrastructure to improve our email deliverability and performance.
• Work collaboratively with global teams, including designers, engineers, and community contributors.
• Support the ongoing stability of our services alongside the team, including occasional participation in a shared on-call rotation.

What you’ll bring:

• 7+ years of experience in software engineering, with significant hands-on experience in web infrastructure, service architecture, or DevOps, including leading large-scale or mission-critical projects.
• 2+ years of email development. This includes building, configuring and maintaining email services and infrastructure, as well as working with email deliverability and authentication concepts (e.g., DMARC/DKIM/SPF, domain warm-up, spam triggers, etc.).
• 5+ years of experience building and maintaining web services throughout the stack, from writing backend services to deploying and monitoring them in the cloud.
• 2+ years of experience with Python 3.
• Proven track record of owning features end-to-end, from gathering requirements to the delivery and maintenance of the final product.
• Great communication skills (both written and verbal), documentation skills, and the ability to work with a multi-disciplinary, geographically distributed team.
• Deep respect for the different skills and perspectives that people of varied technical and non-technical backgrounds bring to a team.
• Experience working remotely and asynchronously across multiple teams and timezones.
• Ability to collaborate effectively with developers, designers, and product managers to achieve quality outcomes.
• Commitment to open-source development and open standards.

Bonus points for:

• Experience with Keycloak or other OIDC services
• Experience with Rust or Java
• Experience with DevOps tooling like Kubernetes, or Infrastructure as Code tools like Terraform
• Previous experience contributing to open-source projects or engaging with open-source communities.

Work Environment:

You’ll work with our passionate staff and open-source community members from all over the globe to support the mission and objectives of MZLA Technologies Corporation. This is a remote position, open to candidates in regions overlapping with teams in Canada, the US, and Europe. Strong communication and documentation skills are essential for effective collaboration across time zones and disciplines.

Work Environment:

This is a remote position, open to candidates in regions overlapping with teams in Canada, the US, and Europe. Strong communication and documentation skills are essential for effective collaboration across time zones and disciplines.

What you’ll get:

We benchmark our base salaries to local markets and target the 60th percentile of the peer market. The salary ranges for this role are:

• UK: £65,000 - £75,000

In addition to competitive salaries, we offer a comprehensive benefits package designed to support your whole self.

Work Career

• Fully remote work schedule flexibility
• Latest Laptop
• Remote Work Stipend
• Professional Development Stipend
• Access to Udemy Learning Platform
• Industry Conferences
• Company All Hands

Rest Play

• 24 days PTO per year (prorated)
• Your Birthday
• Year-end Company Shutdown
• Wellbeing Days
• Public Holidays
• Other Paid Leave
• Wellbeing Stipend for Personal / Family Activities

Health Family

• Pension Contributions
• Health, Dental, Vision Insurance
• Disability Insurance
• Life Insurance
• Employee Assistance Program
• Paid Parental Leave
• Paid Sick Days

Work Eligibility:

Applicants must reside in and have permanent work authorization for the country location(s) specified in the posting. We are unable to consider applicants outside of these markets at this time. And, we do not provide visa sponsorship.

How to Apply:

Please apply directly through our career page. We carefully review every cover letter and screening question, so take the time to answer each fully. We also value authenticity. We want to hear your perspective, not a bot’s. It's fine to use AI to polish your writing, but not to write your answers. Candidates who submit unoriginal AI generated answers will be disqualified from further screening.

MZLA Technologies Corporation (MZLA) Commitment to diversity, equity and inclusion

MZLA believes in the value of diverse creative practices and forms of knowledge, and knows diversity, equity and inclusion are crucial to and enrich the company’s core mission. We encourage applications from everyone, including members of all equity-seeking communities, such as (but not limited to) women, racialized and Indigenous persons, persons with disabilities, persons of all sexual orientations, gender identities and expressions.

We are an equal opportunity employer. We do not discriminate on the basis of race (including hairstyle and texture), religion (including religious grooming and dress practices), gender, gender identity, gender expression, color, national origin, pregnancy, ancestry, domestic partner status, disability, sexual orientation, age, genetic predisposition, medical condition, marital status, citizenship status, military or veteran status, or any other basis covered by applicable laws. Mozilla will not tolerate discrimination or harassment based on any of these characteristics or any other unlawful behavior, conduct, or purpose.

We will ensure that qualified individuals with disabilities are provided reasonable accommodations to participate in the job application or interview process, to perform essential job functions, and to receive other benefits and privileges of employment, as appropriate. Please contact us athiringaccomodations@thunderbird.net to request accommodation.