Thunderbird is one of the world's most trusted open-source email applications, empowering more than 20 million people globally.
We build privacy-respecting communication and productivity tools.
Our small but growing distributed team includes more than 65 people across seven countries.
Thunderbird is expanding beyond email with Thunderbolt, an open-source AI client designed for organizations that need more control over their data, infrastructure, and model choices.
Responsibilities
Build and ship full-stack features, integrations, and customer-specific customizations in the Thunderbolt codebase, from front-end UI through APIs, services, and deployment configuration.
Work directly with technical partners and enterprise customers to understand their environments, requirements, and constraints, and turn them into technical plans and working software.
Support pilots, proofs of concept, and early production deployments, including partner-hosted and customer-controlled environments.
Diagnose and fix complex issues across the application, infrastructure, identity and access, integration, and data-access layers.
Maintain customer-specific customizations over time so they keep working as the core product evolves.
Spot which customer requests should become general product capabilities.
Bring real-world deployment feedback into roadmap and prioritization discussions.
Write the documentation, deployment guidance, and runbooks that let partners handle routine issues on their own.
Use AI-assisted development tools thoughtfully to move quickly while keeping strong judgment about quality, security, and maintainability.
Requirements
10+ years of professional software engineering experience, including significant time building and shipping production applications with Staff-level scope and impact.
Strong full-stack engineering skills, including modern TypeScript or JavaScript, component-based front-end frameworks, and back-end services, APIs, and integrations.
Meaningful experience working directly with customers, partners, or systems integrators in a technical capacity where you also wrote the code.
Experience building or supporting AI-enabled applications, such as LLM platforms, RAG systems, agents, enterprise search, or data connectors.
Solid understanding of enterprise deployment concerns, including authentication and identity providers, access control, self-hosted and hybrid infrastructure, observability, and reliability.
Judgment about when to build something custom, when to generalize it into the product, and when to push back on a request.
Clear communication skills with both technical implementers and non-technical stakeholders.
Strong collaboration skills, including experience working closely with product managers, designers, engineers, and other cross-functional stakeholders.
Comfort operating independently in an early-stage product where requirements, architecture, and processes are still taking shape.
Bonus points
Experience with self-hosted, private cloud, sovereign, or regulated deployment environments.
Experience with Docker, Kubernetes, CI/CD, and cloud deployment.
Experience working with European enterprise or public sector customers, or with data residency and sovereignty requirements.
Experience supporting security reviews, privacy assessments, or enterprise procurement processes.
Open-source contributions, or experience in open, highly collaborative engineering environments.