Applied AI Engineer

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.