Senior Back End Developer Jobs in Reston, VA (NOW HIRING)

hackajob is collaborating with Twenty to connect them with exceptional professionals for this role.

About the Company

America is under sustained cyber attack. Our adversaries infiltrate our networks, steal our IP, and degrade the digital infrastructure that modern life runs on. They’ve learned—correctly—that those attacks rarely produce consequences.

Twenty was founded to change that, by making our adversaries think twice before they attack us. Our vision is American and allied primacy in cyberspace—a future where they cannot contest us, deterrence is assured, and the free world remains secure.

Founded in 2024, Twenty Technologies (www.twenty.io) industrializes offensive cyber operations for the U.S. and its allies. Headquartered in Arlington, Virginia, Twenty has raised $138M from Accel, Caffeinated Capital, Friends & Family Capital, Point72 Ventures, General Catalyst, and In-Q-Tel.

 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.

What You’ll Do

• 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.

Must Have

• 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 Have

• 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.

Tech Environment (You Might Work With)

• Go (Golang), GraphQL/REST

• Graph databases (Neo4j, AWS Neptune) and complex graph schemas

• NATS and event-driven architectures

• AWS, microservices, containers

• CI/CD pipelines, automated testing frameworks, infrastructure-as-code patterns

• Monitoring and observability tools

Security / Work Environment

Some positions may require eligibility to obtain and maintain a U.S. Government security clearance. This role may involve work in a controlled environment.

Benefits
What's on the table:

• Health. Medical, dental, and vision plan options. Life / AD&D, disability coverage options.

• Family. Paid parental leave for eligible full-time employees. 12 weeks for birthing parents, 4 for non-birthing parents, 6 weeks for adoptive, foster, or intended parents through surrogacy.

• Vacation. Paid holidays and flexible PTO. Take what you need.

• Retirement. 401(k) with pre-tax and Roth options. HSA/FSA options, dependent care FSA.

• At the office. Commuter benefits. On-site garage parking. Bike storage. Building fitness center. Desk setup stipend.

Benefits vary by location, role, and eligibility. Full plan details provided during the interview and offer process.

If this role sounds like you, apply and share with us your interest.

Some positions may require eligibility to obtain a U.S. Government security clearance. Any clearance requirement will be listed in the role description.

Twenty is an equal opportunity employer. We consider all qualified applicants without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, age, veteran status, disability, or any other protected status.

If you need a reasonable accommodation during the hiring process, let us know and we will work with you.