Why Thunderbird?

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

We are open source by design. Our products are developed transparently and in collaboration with a global community of contributors,and that same spirit shapes how we work: collaboratively,inclusively,and with a shared commitment to putting users first.

We are a small but growing company of 60+ people distributed across seven countries. As Thunderbird evolves beyond a single desktop application, we are expanding across desktop, mobile, paid services,and new product experiences that help people and organizations work more effectively without giving up control to big tech ecosystems.

Our revenue model combines user donations, which help keep Thunderbird’s apps freely available,with paid services that coverthe costs of hosted offerings while supporting long-term sustainabilityand continued innovation.

A note about MZLA and Mozilla: MZLA Technologies Corporationis the nonprofit-owned company behind Thunderbirdand part of the Mozilla family. MZLA is separate from Mozilla Corporationand has its own compensation programs, benefits,and employment policies.

To learn more, visit www.thunderbird.net

The opportunity

Thunderbirdis expanding beyond email with Thunderbolt,an open-source AI client designed for organizations that need more control over their data,infrastructure,and model choices.

We’re looking for a Staff Designer to help shape the product experience for Thunderbolt as it moves from early product development into enterprise use cases. This role sits at the intersection of product design, front-end engineering, prototyping,and AI-assisted product development- You’ll turn early product ideas, user needs, partner feedback,and workflow concepts into working prototypesand production-ready user experiences. This is not a role focused only on mockups or design artifacts. You’ll work directly inthe codebase, use AI-assisted development tools thoughtfully,and help definethe interaction patterns that make Thunderbolt intuitive,useful,trustworthy,and enterprise-ready- You should be comfortable operating independentlyin ambiguity, moving quickly from concept to prototype, distinguishing between experiments and production-ready work,and creating reusable productand interaction patterns that help the broader team move faster-

What you’ll do

• Build functional prototypesand product experiments directly inthe Thunderbolt codebase.
• Translate ambiguous product ideas, user workflows, partner feedback,and enterprise needs into clear, usable product experiences-
• Help define interaction patterns for AI-powered chat, search, research, workflow automation, knowledge retrieval,and enterprise administration-
• Use AI-assisted development tools to accelerate prototypingand implementation while maintaining strong judgment around quality, usability, security, accessibility,and maintainability-
• Partner closely with product, design, engineering,and enterprise-facing teams to explore, validate,and refine product direction-
• Contribute production-quality front-end code where appropriate-
• Identify when a prototype should be discarded, refined, generalized, or productionized-
• Improve the usability, accessibility, consistency,and polish of the Thunderbolt user experience-
• Help develop reusable components, interface patterns, or design-system elements that create leverage forthe broader product team-
• Bring a user-centered perspective to technicaland product discussions, especially where AI behavior, user trust, transparency, permissions, or workflow clarity are important-
• Consider enterprise needs when designing product experiences, including data sensitivity, user control, administrative visibility, auditability,and security expectations-
• Contribute to a product culture that values speed, clarity, experimentation, maintainability, responsible AI use,and thoughtful user experience-

What you bring

• 10+ years of relevant experience in design engineering, front-end engineering, UX engineering, product design with strong technical implementation experience, or a closely related role, with demonstrated leadershipand impact beyond individual deliverables-
• Strong front-end engineering skills, including experience with modern JavaScript or TypeScript, component-based frameworks,and building prototypes or production features directly in an application codebase-
• Strong productand interaction design judgment, including usability, accessibility, information architecture, workflow design,and product polish-
• Experience designing, prototyping, or building AI-enabled product experiences, such as chat, search, research tools, agents, automation, knowledge interfaces, or workflow tools where user trust, context, output quality,and human oversight are central to the experience-
• Experience translating ambiguous product concepts into usable workflows, prototypes,and shipped product experiences,with the judgment to balance speed, quality, maintainability, learning,and product risk-
• Experience providing technical or product leadership through mentoring, cross-functional coordination, reusable patterns, project ownership, or influence beyond individual deliverables-
• Practical awareness of AI, privacy, security,and regulatory considerations that may affect product experience, including transparency, user control, permissions, data handling,and trust; familiarity with frameworks such as the EU AI Act, Cyber Resilience Act, HIPAA, or comparable responsible AI, privacy,and security requirements-
• Strong communicationand collaboration skills, including experience working closely with product managers, designers, engineers,and other cross-functional stakeholders-
• Portfolio, case studies, shipped work, or examples demonstrating design-to-code execution, interactive prototypes, or product experience improvements-

Bonus points for

• Experience with enterprise software, developer tools, productivity tools, collaboration tools, self-hosted software, or other technical user workflows-
• Experience contributing to design systems, component libraries, reusable front-end architecture, or shared product interaction patterns-
• Familiarity with user research, usability testing, product discovery, feature instrumentation, or rapid experimentation methods-
• Experience working in open-source or highly collaborative engineering environments-

What Success Looks Like

In this role, you will help Thunderbolt move from ideasand early workflows into clear, usable, high-quality product experiences. You’ll create prototypesthat clarify direction, reusable patterns that help the team move faster,and production experiences that make AI-powered workflows easier to understand and trust- A successful Staff Design Engineer will help the team decide what is worth building, what needs more testing,and what should not move forward. You’ll raisethe quality of Thunderbolt’s user experience while helpingthe product remain fast-moving, practical,and enterprise-ready-

Work environment

You’ll work with our passionate staffand open-source community members from all over the globe to supportthe missionand objectives of MZLA Technologies Corporation. In this role, you’ll also collaborate closely with engineering, product, design, enterprise-facing teams, contractors, and external contributors working on Thunderbolt- This is a remote, full-time position. Strong communicationand documentation skills are essential for effective collaboration across time zonesand disciplines-

Compensation & Benefits

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

• Canada: $155,000 - $175,000 CAD
• US: $185,000 - $205,000 USD

We may consider candidateswith strong skills but less thanthe required experience. Title, leveland compensation will be determined based on qualificationsand experience- In addition to competitive salaries, we offer a comprehensive benefits package designed to support your whole self-

Work & career

• Fully remote work & schedule flexibility
• Company-provided laptop
• Annual bonus program
• Monthly remote work stipend
• Annual professional development stipend
• Access to Coursera learning platform
• Industry conferences
• Company all-handsand team gatherings

Rest & play

• 24 days PTO per year (prorated)
• Your birthday
• Year-end company shutdown
• 9 wellbeing days
• Public holidays
• Other paid leave
• Quarterly wellbeing stipend for personal / family activities

Health & family

• 401(k) / RRSP contributions
• Health, dental, & vision insurance
• Disability insurance
• Life insurance
• Employee assistance program
• Paid parental leave
• Paid sick days