Applied AI Engineer

About the 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 http://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 and ship language-model-powered systems that strengthen Twenty’s mission-critical cyber capabilities for U.S. national security. You’ll own the end-to-end workflow—from curating specialized datasets and post-training models to deploying reliable inference and retrieval systems in production. You’ll partner closely with product and engineering to translate real operational needs into high-performing AI features, operating across cloud and on-premises environments where speed, correctness, and security matter.

WHAT YOU’LL DO

- Create, clean, and maintain high-quality training and evaluation datasets for specialized AI use cases.

- Fine-tune language models (small specialized through medium foundation models) for mission needs.

- Implement post-training and alignment approaches to improve task performance and reliability.

- Build retrieval-augmented generation (RAG) systems that ground model outputs in external knowledge.

- Develop and optimize model serving infrastructure for production deployments.

- Design evaluation frameworks and test harnesses to measure quality, latency, and regressions.

- Integrate AI capabilities into applications and workflows using modern orchestration frameworks.

- Collaborate with cross-functional partners to identify high-leverage use cases and deliver solutions.

- Produce clear technical documentation for models, datasets, and operational processes.

WHO YOU ARE

- You’re motivated by real-world outcomes and want your work to directly impact national security missions.

- You care about rigor: clean data, measurable evaluation, and repeatable experiments beat demos.

- You balance research curiosity with product instincts—you ship, observe, iterate, and harden.

- You’re comfortable working across cloud and on-premises constraints and adapting to the environment.

- You communicate clearly with engineers and non-ML partners, and you write documentation people use.