Senior Backend Software Engineer

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.

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.

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.

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

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.

• 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

• Due to U.S. government contract and security requirements, this role is limited to U.S. citizens.
• Some positions may also require eligibility to obtain and maintain a U.S. Government security clearance.
• Any active clearance requirement will be listed in the role description.