Senior Product Engineer

About the role

Plain is redefining customer support for the next generation of B2B companies. We are building the fastest, most powerful platform to help companies move beyond reactive support and build true customer relationships. Some of the world's most forward-thinking companies like Cursor, Raycast, and Granola trust Plain to unify all customer interactions, enable faster team collaboration, and supercharge their workflows with AI. B2B customer support is undergoing a seismic shift where AI transforms how companies engage with customers, moving support from a siloed function to a company-wide effort across Slack, Discord, and any other channel you talk to customers in. The old way that is slow, manual, and disconnected no longer works. This role is hybrid with 3 days a week in our London office. You will own the infrastructure and platform work that allows our AI capabilities to exist and scale reliably. You will partner closely with product and design to turn high level concepts into production ready features that directly serve customers. You will ensure that AI features are delivered with a focus on safety, observability, and performance from the very first release. You will solve ambiguous problems where the right technical tradeoffs directly impact the customer experience. This is a role for someone who wants to build the foundation that lets our AI features shine in real world usage.

Key facts

What you'll do

• Own and ship AI features such as our agents, assistants, insights and more from concept to production.
• Design and implement backend services for AI integrations and data pipeline.
• Build robust APIs and abstractions for internal AI usage.
• Drive system scalability through caching, optimization, and processing patterns.
• Contribute to and drive the evolution of the infrastructure for AI including architecture, evaluation, and iteration pipelines.
• Solve complex AI challenges around accuracy, reliability, and quality using rigorous quantitative approaches.
• Advocate for our work externally by writing, speaking, and engaging with the broader AI community.
• Ensure AI features are reliable and performant in production by defining and tracking the right metrics.
• Collaborate with product managers, designers, and other engineers to deliver high quality customer facing features.
• Implement monitoring and debugging tools to help the team understand and improve AI behavior in context.
• Translate product requirements into technical specifications that guide implementation and testing.
• Optimize end to end workflows to reduce latency and improve the user experience for both internal and external users.
• Maintain and evolve existing services to keep them secure, scalable, and easy to understand.

Requirements

• Are an experienced backend engineer who has shipped AI products in the OpenAI and Anthropic era, especially text and data heavy AI applications.
• Have hands on experience with LLM orchestration and LLM API optimization including costs and latency.
• Are familiar with RAG architectures and technologies.
• Have AI observability experience and understand how to measure whether AI features are actually improving outcomes.
• Have a clear perspective on what makes a great AI product and prefer applying AI with precision and nuance rather than as a gimmick.
• Are product minded and customer focused in how you build software and measure success by user impact instead of only technical elegance.
• Are self driven, impact focused, and thrive in a fast moving, high ownership environment.
• Are comfortable working with ambiguity and making decisions when information is incomplete.
• Have strong written communication skills to clearly document decisions and collaborate asynchronously.
• Are able to work in the London office three days per week on a regular basis.
• Have experience working with production grade infrastructure and modern software development practices.
• Have a strong understanding of software design patterns and system architecture.

Nice to have

• Bonus: you have experience with agent frameworks and design.

Practical notes

This role is hybrid with 3 days a week in our London office. We expect full time commitment and engagement. There may be limited travel required as part of role activities. We do not currently sponsor visas for this role. Applicants must meet the eligibility requirements listed in the requirements section without exception. The compensation details are not specified in the available information from SOURCE.