---
title: 'Applied AI Engineer at Twenty'
canonical: 'https://feeny.ai/job/applied-ai-engineer-twenty-arlington-mgr70h5kv8de'
type: 'job'
last_seen: '2026-09-07'
---

# Applied AI Engineer at Twenty

- **Company:** Twenty
- **Location:** Arlington, VA
- **Compensation:** $159k–$263k
- **Employment:** full-time
- **Work type:** onsite
- **Posted:** 2025-09-04
- **Last confirmed live:** 2026-09-07
- **Apply:** https://jobs.ashbyhq.com/twenty/490ea911-5a82-449a-89ed-c40f2beff9d5

## Job description

## 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.
- You think in systems: models, retrieval, infrastructure, and feedback loops all have to work together.
- You thrive in fast-moving teams with high standards, direct feedback, and high ownership.

## MUST HAVE

- You have 4+ years of professional software development experience building and supporting ML/AI-enabled applications.
- You have strong Python skills and deep learning experience with PyTorch, TensorFlow, or JAX.
- You have hands-on experience with LLM post-training methods (e.g., continued pre-training, SFT, RLHF, DPO, PPO, GRPO).
- You have experience curating, cleaning, and preprocessing datasets for training and evaluation.
- You have working knowledge of relational, graph, and vector database concepts.
- You have experience designing or using evaluation metrics and testing procedures for LLMs and agents.
- You have experience integrating LLM/agent systems using frameworks like Pydantic-AI, LangChain/LangGraph, or CrewAI.
- You have a Bachelor’s degree in Computer Science, Software Engineering, or a related field (or equivalent practical experience).

## NICE TO HAVE

- You have deployed models to production and supported them through real-world usage and incidents.
- You have experience with distributed training systems and performance debugging at scale.
- You have implemented quantization or other optimization techniques to improve inference efficiency.
- You have strong prompt engineering and model alignment instincts for reliability and control.
- You have experience building MLOps/LLMOps/AgentOps practices (versioning, rollout, monitoring).

## TECH ENVIRONMENT (YOU MIGHT WORK WITH)

- Deep learning stacks: PyTorch, TensorFlow, JAX
- LLMOps and serving: vLLM, TensorRT, ONNX
- Retrieval and storage: pgvector, ChromaDB, Pinecone, Milvus, Weaviate; relational/graph databases
- Orchestration: Pydantic-AI, LangChain/LangGraph, CrewAI
- Infra: Docker, Kubernetes; cloud platforms (AWS, GCP, Azure)
- Experiment and artifact tracking: dataset/prompt/model versioning

## SECURITY / WORK ENVIRONMENT

Must be eligible to obtain and maintain a U.S. Government security clearance.

## 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.

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.

## About Twenty

## Company Overview
- **One-liner**: Twenty builds and scales the software and capabilities of modern cyber conflict, industrializing the American arsenal for the war of now.
- **Entity Type**: Private (Series B; $138M total funding as of June 2026)
- **Headquarters**: Arlington, Virginia, United States
- **Founded**: 2024
- **Founders**: Joe Lin (CEO), Peter S., Skyler O.

## Core Business
- **Primary industry**: Cyber warfare and national security (Computer and Network Security)
- **Target customers**: U.S. military and Intelligence Community (B2G)
- **Mission**: Deliver industrial-scale cyber capabilities, ensuring the U.S. and its allies are able to deter and defeat their adversaries [twenty.io/careers](https://twenty.io/careers/).

## Products & Services
- **Cyber Warfare Platform**: Intelligent, autonomous end-to-end systems that accelerate the entire offensive cyber operations lifecycle. Encodes elite tradecraft directly into software, transforming workflows that once took weeks of manual effort into automated, continuous operations across hundreds of targets simultaneously. [twenty.io](https://twenty.io/)

## Market Standing
- **Valuation/Market Cap**: Not disclosed
- **Key Metric**: Total funding $138M (as of June 2026), including a $38M Series A led by Caffeinated Capital in November 2025 and a subsequent $100M round in June 2026 [aventure.vc](https://aventure.vc/companies/twenty-arlington-va-us) [prnewswire.com](https://www.prnewswire.com/news-releases/twenty-raises-38m-to-transform-cyber-warfare-at-industrial-scale-302622230.html)
- **Notable Investors/Partners**: Caffeinated Capital, General Catalyst, In-Q-Tel, Accel, Point72 Ventures, Friends & Family Capital [twenty.io/careers](https://twenty.io/careers/)
- **Growth Signals**: Headcount grew 245% YoY, reaching ~50 employees; 34+ active job postings as of July 2026; emerged from stealth in November 2025 with over $100M in government contracts [linkedin.com](https://www.linkedin.com/company/twentytechnologies) [prnewswire.com](https://www.prnewswire.com/news-releases/twenty-raises-38m-to-transform-cyber-warfare-at-industrial-scale-302622230.html)

## Competitive Advantages
- **Elite team**: Composed of the top 0.1% of cyber operators (from USCYBERCOM, NSA, DHS, U.S. Marine Corps, Navy, Army) and proven builders (from Palantir, Palo Alto Networks, Expanse) [twenty.io/careers](https://twenty.io/careers/)
- **Proven track record**: The founding team built the most successful SaaS cyber product in U.S. military history and defended tens of thousands of networks [twenty.io](https://twenty.io/)
- **100X improvement**: Industrial-scale automation replaces manual, bespoke methods, fundamentally reshaping how the U.S. and allies engage in cyber conflict [twenty.io](https://twenty.io/)
- **Strategic backing**: Supported by top defense-tech VCs and In-Q-Tel (the CIA’s venture arm)

## Strategic Focus
- Accelerating the delivery of intelligent, autonomous cyber warfare systems to close critical gaps in U.S. offensive capabilities
- Countering adversaries such as the People’s Republic of China (PRC) in the cyber domain
- Expanding partnerships across the U.S. military and Intelligence Community, with deployments already in active combat operations [prnewswire.com](https://www.prnewswire.com/news-releases/twenty-raises-38m-to-transform-cyber-warfare-at-industrial-scale-302622230.html)

## Why Work Here
- **Mission-driven impact**: Your code directly affects mission success or failure — “the difference between mission success and mission failure” [twenty.io/careers](https://twenty.io/careers/)
- **Elite peer group**: Work alongside top 0.1% cyber operators and world-class technologists
- **Rapid growth**: 245% headcount increase YoY; 39 open roles across engineering, product, finance, growth, and talent [twenty.io/careers](https://twenty.io/careers/)
- **Culture**: “Serious work, savage wit, zero excuses.” Emphasis on solving “crazy-hard problems” that nation-state adversaries face. “No one is coming to save us, so we’d better do it ourselves.” [twenty.io/careers](https://twenty.io/careers/)
- **Work environment**: Primarily on-site at secure locations (Arlington, VA HQ; Fort Meade, MD; San Antonio, TX; Augusta, GA). Most roles require relocation to the Washington, DC area or other government facilities. [twenty.io/careers](https://twenty.io/careers/)
- **Notable perks**: Not explicitly detailed, but the focus is on building revolutionary capabilities for national security rather than typical engagement metrics.

## Sources
1. [twenty.io](https://twenty.io/)
2. [twenty.io/careers](https://twenty.io/careers/)
3. [linkedin.com](https://www.linkedin.com/company/twentytechnologies)
4. [prnewswire.com](https://www.prnewswire.com/news-releases/twenty-raises-38m-to-transform-cyber-warfare-at-industrial-scale-302622230.html)
5. [aventure.vc](https://aventure.vc/companies/twenty-arlington-va-us)

## Other roles at Twenty

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- [Senior Accountant (First Hire)](https://feeny.ai/job/senior-accountant-first-hire-twenty-arlington-at0x228y6rbj) — Arlington, VA
- [Senior / Staff Forward Deployed Software Engineer - TS/SCI Cleared](https://feeny.ai/job/senior-staff-forward-deployed-software-engineer-ts-sci-cleared-twenty-chantilly-sjhj4pgb897b) — Chantilly, VA
- [Staff Product Manager](https://feeny.ai/job/staff-product-manager-twenty-new-york-smpbxyp29dwt) — New York, NY
- [IT Security Engineer](https://feeny.ai/job/it-security-engineer-twenty-arlington-ghw0n54mkva0) — Arlington, VA
- [Director, Software Engineering](https://feeny.ai/job/director-software-engineering-twenty-arlington-x1e02f23d4cs) — Arlington, VA
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