About the Role

Flexgen is a Seed-stage AI infrastructure startup building a high-throughput, production-grade AI gateway for the next generation of AI products. As Founding Engineer, you will design and own core backend infrastructure, work on distributed systems and Kubernetes, and collaborate directly with founders to shape technical direction. This is an on-site role in London.

Responsibilities

Design, build, and own core backend infrastructure for a high-throughput AI gateway serving billions of tokens per day.
Architect and evolve a pragmatic microservices system, including a core LLM gateway in Go and auxiliary ML/AI services in Python.
Make critical decisions around distributed systems design, database selection, caching strategies, and API platform architecture.
Profile and optimize performance for high-traffic, latency-sensitive systems with sub-20ms SLAs.
Work hands-on with Kubernetes to deploy, manage, and scale services reliably.
Collaborate directly with founders to translate product vision into robust, scalable engineering solutions.

Requirements

5+ years of experience building backend services using a compiled language, with Go (Golang) strongly preferred.
Strong experience in distributed systems design and scalability.
Hands-on Kubernetes expertise in production environments.

ActiveCampaign

Chicago · US · 655+ employees

ActiveCampaign is a SaaS platform providing customer experience automation, including tools for marketing, sales, and email automation, as well as CRM functionalities. It leverages AI features to help businesses connect and engage with their customers.