Senior Backend Software Engineer
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Before you apply
LocationArlington, VA
Work modeon-site
Typefull-time
SenioritySenior
Experience5+ yrs
DepartmentEngineering
Company size201–500 people
PostedSep 28, 2026 · 1mo ago
Verified live2d ago
Reposted once in the last 6 monthsEarliest listing first seen Sep 8, 2026
How we check a job is still liveAt a glanceSummarised by Seekless from the posting.
5+ years of professional software development experience building backend (or full-stack) applications
Strong proficiency with Go (Golang) and shipped production services with it
Experience working with graph databases (Neo4j, AWS Neptune, or similar), including schema design and query performance
Working knowledge of event-driven architectures and message queues/streaming systems
Experience building and maintaining APIs (REST and/or GraphQL)
Experience with cloud infrastructure, ideally AWS, and understand cloud-native deployment patterns
Hands-on experience with containerization and microservices architectures
Strong foundation in secure coding practices and can reason about security tradeoffs
Bachelor's degree in Computer Science, Software Engineering, or a related field, or equivalent practical experience
Delivered software in defense, security, or other mission-critical environments
Built systems for analysts, operators, or high-tempo users where speed and reliability matter
Integrated AI/ML capabilities into production systems (inference, pipelines, or tooling)
Experience with large-scale data processing and analytics workloads
Contributed meaningfully to open-source projects
Used observability tooling (metrics, tracing, logging) to debug and improve production systems
U.S. Citizenship required
No active clearance required; however, eligibility to obtain and maintain a U.S. Government security clearance may be needed
Skills
Go
Golang
Neo4j
AWS Neptune
graph databases
event-driven architectures
NATS
message queues
streaming systems
REST
GraphQL
AWS
containerization
microservices
CI/CD
secure coding
automated testing
infrastructure-as-code
observability tooling
metrics
tracing
logging
Benefits
Medical insurance
Dental insurance
Vision insurance
Life insurance
Disability insurance
Paid parental leave
401(k)
Flexible PTO
HSA
FSA
Dependent care FSA
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 $168M from Khosla Ventures, Accel, Caffeinated Capital, Friends & Family Capital, Point72 Ventures, General Catalyst, and In-Q-Tel.
Mission | On Site | Full Time | U.S. Citizenship Required / No Active Clearance Required
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
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Design and implement scalable backend services in Go that improve operator decision-making and response.
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Build high-performance APIs that power customer-facing workflows and internal platform capabilities.
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Model complex relationships in graph databases and optimize schemas and queries for speed and clarity.
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Implement event-driven systems (e.g., with NATS) to process real-time operational data streams.
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Develop and maintain automated tests to protect correctness, security, and performance as the system evolves.
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Build and operate microservices deployed on AWS, with an eye toward resilience and cost-aware scaling.
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Create and improve CI/CD pipelines that enable fast, secure delivery of new capabilities.
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Partner with cyber operations experts to translate domain needs into robust product features.
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Collaborate with frontend engineers on API contracts and data structures that are efficient and usable.
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Evaluate new technologies and patterns that could unlock better operational outcomes.
Who You Are
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You care about building systems that have real-world impact, especially in national security and defense of democracies.
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You’re excited by hard backend problems: throughput, latency, correctness, and operability under pressure.
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You take pride in clean interfaces—APIs that are intuitive, consistent, and built to evolve.
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You think in systems: data models, services, and workflows that work together reliably.
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You’re pragmatic and iterative—ship value quickly, then harden, measure, and improve.
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You collaborate well across disciplines, communicate clearly, and welcome direct feedback.
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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)
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Go (Golang), GraphQL/REST
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Graph databases (Neo4j, AWS Neptune) and complex graph schemas
•
NATS and event-driven architectures
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AWS, microservices, containers
•
CI/CD pipelines, automated testing frameworks, infrastructure-as-code patterns
•
Monitoring and observability tools
Benefits
What’s on the table:
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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.
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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.
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, consistent with applicable law.
If you need a reasonable accommodation during the hiring process, let us know and we will work with you.