Senior Backend Engineer

Twenty•Washington, DC

About The Position

At Twenty, we're taking on one of the most critical challenges of our time: defending democracies in the digital age. We develop revolutionary technologies that operate at the intersection of the cyber and electromagnetic domains, where the speed of operations exceeds human sensing and complexity transcends conventional boundaries. Our team doesn't just solve problems – we deliver game-changing outcomes that directly impact national security. We're pragmatic optimists who understand that while our mission of protecting America and its allies is challenging, success is possible. Role Summary You’ll build the backend systems that power Twenty’s cyber and electromagnetic capabilities—software that ingests real-time operational signals, models complex relationships, and serves high-throughput APIs at machine speed. You’ll design and ship reliable services in Go, working with known-hard problems like graph data modeling, event-driven architectures, and performance at scale. You’ll partner closely with product, frontend, and domain experts to turn operator needs into durable platform capabilities. This role spans both cloud and on-premises environments supporting mission-critical U.S. national security outcomes. Who You Are You care about building systems that have real-world impact, especially in national security and defense of democracies. You’re excited by hard backend problems: throughput, latency, correctness, and operability under pressure. You take pride in clean interfaces—APIs that are intuitive, consistent, and built to evolve. You think in systems: data models, services, and workflows that work together reliably. You’re pragmatic and iterative—ship value quickly, then harden, measure, and improve. You collaborate well across disciplines, communicate clearly, and welcome direct feedback. You default to ownership: you notice gaps, propose solutions, and drive them to completion.

Requirements

You have 5+ years of professional software development experience building backend (or full-stack) applications.
You have strong proficiency with Go (Golang) and have shipped production services with it.
You have experience working with graph databases (Neo4j, AWS Neptune, or similar), including schema design and query performance.
You have working knowledge of event-driven architectures and message queues/streaming systems.
You have experience building and maintaining APIs (REST and/or GraphQL).
You have experience with cloud infrastructure, ideally AWS, and understand cloud-native deployment patterns.
You have hands-on experience with containerization and microservices architectures.
You have a strong foundation in secure coding practices and can reason about security tradeoffs.
You have a bachelor’s degree in Computer Science, Software Engineering, or a related field, or equivalent practical experience.

Nice To Haves

You’ve delivered software in defense, security, or other mission-critical environments.
You’ve built systems for analysts, operators, or high-tempo users where speed and reliability matter.
You’ve integrated AI/ML capabilities into production systems (inference, pipelines, or tooling).
You have experience with large-scale data processing and analytics workloads.
You’ve contributed meaningfully to open-source projects.
You’ve used observability tooling (metrics, tracing, logging) to debug and improve production systems.

Responsibilities

Design and implement scalable backend services in Go that improve operator decision-making and response.
Build high-performance APIs that power customer-facing workflows and internal platform capabilities.
Model complex relationships in graph databases and optimize schemas and queries for speed and clarity.
Implement event-driven systems (e.g., with NATS) to process real-time operational data streams.
Develop and maintain automated tests to protect correctness, security, and performance as the system evolves.
Build and operate microservices deployed on AWS, with an eye toward resilience and cost-aware scaling.
Create and improve CI/CD pipelines that enable fast, secure delivery of new capabilities.
Partner with cyber operations experts to translate domain needs into robust product features.
Collaborate with frontend engineers on API contracts and data structures that are efficient and usable.
Evaluate new technologies and patterns that could unlock better operational outcomes.