Sr. Software Development Engineer, Annapurna Labs

AWS Networking builds the infrastructure that powers every customer workload in the cloud. ENA Express is a next-generation EC2 networking feature that leverages the Scalable Reliable Datagram (SRD) protocol — developed by AWS — to deliver industry-leading networking performance: dramatically lower tail latency, higher bandwidth utilization, and consistent packet delivery at scale. We are looking for a Senior Software Development Engineer to join the ENA Express team. You will design, build, and own features across the full ENA Express software stack: Firmware on the Nitro-Card, user-space libraries, control plane components, and the performance analytics systems that help our customers get the most out of their network. This is high-ownership work — your code runs on a fleet of millions of EC2 instances, supporting customers who demand the absolute best from their network, including HPC clusters, large-scale ML training, financial services, and other latency-critical applications. Key job responsibilities • Design and develop features across the AWS Networking software stack on Nitro Cards. • Deep-dive into ENA Express and the underlying SRD protocol and L3/L4 networking to optimize packet delivery, reduce tail latency, and improve bandwidth utilization. • Collaborate with hardware and firmware partners to define software/hardware interfaces and surface programmable capabilities to the software layer • Partner with EC2 platform and service teams to integrate ENA Express features into the broader AWS networking ecosystem • Mentor junior and mid-level engineers, lead design reviews, and champion engineering best practices across the team • Drive operational excellence: build observability, contribute to on-call health, and lead incident response and post-mortems About the team We are a team of senior engineers with deep expertise in systems software, networking protocols, and EC2 infrastructure. Our work spans the full stack — from the Firmware on the driver Card, and NIC driver layer up through the EC2 control plane — and we collaborate closely with hardware, firmware, and platform partners. We care deeply about technical craft, operational quality, and each other’s growth. Diverse Experiences Amazon values diverse experiences. Even if you do not meet all of the preferred qualifications and skills listed in the job description, we encourage candidates to apply. If your career is just starting, hasn’t followed a traditional path, or includes alternative experiences, don’t let it stop you from applying. Work/Life Balance We value work-life harmony. Achieving success at work should never come at the expense of sacrifices at home, which is why we strive for flexibility as part of our working culture. When we feel supported in the workplace and at home, there’s nothing we can’t achieve in the cloud. Inclusive Team Culture Here at AWS, it’s in our nature to learn and be curious. Our employee-led affinity groups foster a culture of inclusion that empower us to be proud of our differences. Mentorship and Career Growth We’re continuously raising our performance bar as we strive to become Earth’s Best Employer. That’s why you’ll find endless knowledge-sharing, mentorship and other career-advancing resources here to help you develop into a better-rounded professional.