Lead Machine Learning Engineer - AI Agents

Summary

Join Upwork, the world’s largest work marketplace, as a Lead AI/ML Engineer to design and deliver cutting-edge infrastructure and models for agentic LLM workflows. You will work at the intersection of research and production, leading high-impact projects, mentoring others, and contributing to the broader AI research community. This role involves architecting infrastructure for agent-based LLM systems, training custom models, leading cross-functional collaboration, mentoring engineers and researchers, translating experimental ideas into production systems, and publishing innovations. Upwork offers a remote-first work environment with benefits including comprehensive medical coverage, unlimited PTO, a 401(k) plan with matching, 12 weeks of paid parental leave, and an Employee Stock Purchase Plan. The annual base salary range is $175,500—$277,500 USD, with eligibility for an annual bonus plan or sales incentive plan and participation in a long-term equity incentive program.

Requirements

• Strong proficiency in Python and modern ML frameworks such as PyTorch or TensorFlow, with experience developing and deploying AI systems
• Deep understanding of core ML concepts, including transformers, generative models, and agent architectures such as MCP or A2A
• Experience training large models on GPU clusters and integrating LLMs with external tools via APIs or orchestration frameworks
• Comprehensive understanding of foundational deep learning, machine learning concepts, and state-of-the-art GenAI models
• Hands-on experience training custom LLMs on GPUs and working with Retrieval-Augmented Generation (RAG) systems
• Proven ability to build end-to-end ML pipelines—from data prep and experimentation to production deployment—in a cloud-native environment
• A growth mindset, strong communication skills, and the ability to translate complex technical work to stakeholders across functions

Responsibilities

• Architect and implement core infrastructure to support agent-based LLM systems, including multi-agent pipelines, RAG, and real-time orchestration
• Train and fine-tune custom models, including LLMs and foundation models, to solve unique Upwork-specific challenges
• Lead cross-functional collaboration across engineering, product, and research teams to align technical solutions with business impact
• Mentor and guide engineers and researchers, helping foster a high-performing, inclusive team culture grounded in AI excellence
• Translate experimental ideas into reliable, scalable production systems by applying best practices in AI engineering and deployment
• Publish and share innovations where appropriate, contributing to Upwork’s visibility in the broader AI/ML research community

Preferred Qualifications

Demonstrated experience working in R&D environments; publications in major AI/ML conferences are a plus, but not required

Benefits

• Comprehensive medical coverage for you and your family
• Unlimited PTO
• A 401(k) plan with matching
• 12 weeks of paid parental leave
• An Employee Stock Purchase Plan