Lead Machine Learning Engineer - Applied Scientist

1 Month ago • All levels • Research Development • $175,500 PA - $277,500 PA

Job Summary

Job Description

Upwork is seeking a Lead Machine Learning Engineer / Applied Scientist to enhance the performance of LLMs and AI agents. This role involves building feedback loops, defining success metrics, and driving improvements in AI systems. You will collaborate with research, engineering, and product teams to integrate your insights into Upwork's AI infrastructure, design testbeds for agentic workflows, refine prompts and orchestration strategies, and guide the iteration of ML-powered features. Your work will directly impact the success of advanced AI initiatives and shape the evaluation and iteration processes within the AI product lifecycle at scale.
Must have:
  • Deep familiarity with LLM evaluation methodologies
  • Hands-on experience in Python and ML frameworks (e.g., PyTorch)
  • Proven ability to align ML evaluation with business goals
  • Comfortable operating in ambiguous problem spaces
  • Passion for continuous improvement
Good to have:
  • Experience with benchmark selection
  • Prompt sensitivity analysis
  • Human-in-the-loop review processes
  • Ability to analyze ML outputs and drive performance iteration
  • Strong documentation habits
  • Collaborative and inclusive working style
Perks:
  • Comprehensive medical coverage
  • Unlimited Paid Time Off (PTO)
  • 401(k) plan with matching
  • 12 weeks of paid parental leave
  • Employee Stock Purchase Plan

Job Details

Upwork ($UPWK) is the world’s largest work marketplace, connecting businesses with highly skilled professionals worldwide. From entrepreneurs to Fortune 100 enterprises, companies trust Upwork’s platform to access expert talent, leverage AI-powered work solutions, and drive meaningful business outcomes.

Upwork’s AI-powered platform has facilitated over $20 billion in economic opportunity for professionals worldwide. With professionals spanning 10,000+ skills, including AI and machine learning, software development, sales and marketing, customer support, finance and accounting, and more, Upwork empowers businesses of all sizes to scale, innovate, and build agile teams.


We’re looking for a Lead Machine Learning Engineer / Applied Scientist with a passion for rigorously evaluating and improving the performance of LLMs and AI agents. In this role, you will focus on building feedback loops, defining success metrics, and driving measurable improvements to the quality and reliability of our intelligent systems. This is a rare opportunity to shape how evaluation and iteration are embedded in the product lifecycle for AI at scale.

You’ll partner closely with research, engineering, and product teams to embed your insights into Upwork’s AI infrastructure. This includes designing testbeds for agentic workflows, refining prompts and orchestration strategies, and guiding the iteration of ML-powered features to deliver better outcomes for our users. Your work will directly influence the success of our most advanced AI initiatives.

Responsibilities

  • Develop and own evaluation pipelines for agentic LLM systems, enabling consistent measurement across simulation, benchmark, and live-user scenarios.
  • Define and iterate on quality metrics that guide the training, tuning, and deployment of LLMs and agents.
  • Lead experiments to assess and improve system behaviors across dimensions such as correctness, safety, latency, and helpfulness.
  • Collaborate with cross-functional partners to integrate insights from evaluation into product development and deployment pipelines.
  • Build automated testing and monitoring tools that scale with the complexity of agent behaviors and LLM responses.
  • Share findings and improvements through documentation, dashboards, and internal demos, contributing to a culture of continuous learning and excellence.

What it takes to catch our eye

  • Deep familiarity with evaluation methodologies for LLMs or autonomous agents, including benchmark selection, prompt sensitivity analysis, and human-in-the-loop review processes.
  • Hands-on experience in Python and ML frameworks such as PyTorch, with the ability to analyze outputs and drive performance iteration.
  • Proven ability to work across teams and disciplines to align ML evaluation work with product and business goals.
    Comfortable operating in ambiguous problem spaces and taking initiative to define structure, priorities, and impact.
  • Passion for continuous improvement, strong documentation habits, and a collaborative, inclusive working style.

Come change how the world works.

At Upwork, you’ll shape the future of work for a global, remote-first workforce, creating economic opportunities for professionals worldwide. While we have a physical office in Palo Alto, we currently hire full-time employees in 21 U.S. states, making it easier than ever to join our mission from wherever you call home.

Our culture is built on trust, risk-taking, customer focus, and excellence, all in service of our core mission: to create economic opportunities so people have better lives. We embrace authenticity and inclusion, encouraging everyone to bring their whole selves to work. Personal and professional growth is a priority here, supported through development programs, mentorship, and our Upwork Belonging Communities.

We’re proud to offer benefits that go beyond the basics, including comprehensive medical coverage for you and your family, unlimited PTO, a 401(k) plan with matching, 12 weeks of paid parental leave, and an Employee Stock Purchase Plan. Visit our Life at Upwork page to learn more about our values, working principles, and the overall employee experience.

Ready to help shape the future of work? Check out our Careers page and follow us on LinkedIn, Facebook, Instagram, TikTok, and X to learn more about life at Upwork.

Upwork is an Equal Opportunity Employer committed to recruiting and retaining a diverse and inclusive workforce. We do not discriminate based on race, religion, color, national origin, gender (including pregnancy, childbirth, or related medical conditions), sexual orientation, gender identity, gender expression, age, status as a protected veteran, status as an individual with a disability, genetic information, or other legally protected characteristics under federal, state, or local law.

Please note that a criminal background check may be required once a conditional job offer is made. Qualified applicants with arrest or conviction records will be considered in accordance with applicable law, including the California Fair Chance Act and local Fair Chance ordinances.

The annual base salary range for this position  is displayed below. The range displayed reflects the minimum and maximum salary for this position, and individual base pay will depend on your skills, qualifications, experience, and location. Additionally, this position is eligible for the annual bonus plan or sales incentive plan and eligibility to participate in our long term equity incentive program.

Annual Base Compensation

$175,500 - $277,500 USD

To learn more about how Upwork processes and protects your personal information as part of the application process, please review our Global Job Applicant Privacy Notice

Similar Jobs

Wind River - Senior Engineer - Network Stack

Wind River

Bengaluru, Karnataka, India (Hybrid)
2 Months ago
Assist software  - Oracle NetSuite Senior Developer

Assist software

Romania (On-Site)
4 Months ago
Scopely - Lead Product Manager, Economy - Monopoly GO!

Scopely

Barcelona, Catalonia, Spain (Remote)
8 Months ago
Coherent corp. - Senior Principal Electrical Design Engineer

Coherent corp.

Fremont, California, United States (On-Site)
3 Months ago
Capgemini - Financial Controller

Capgemini

Mumbai, Maharashtra, India (On-Site)
3 Months ago
Well - Senior Machine Learning Engineer

Well

New York, United States (On-Site)
1 Month ago
Valeo - AM/DM- R&D (Mechanical Design Leader)

Valeo

Pune, Maharashtra, India (On-Site)
8 Months ago
Ubisoft - Lead R&D Scientist

Ubisoft

Shanghai, Shanghai, China (On-Site)
6 Months ago
Match Group - Staff Software Engineer, Machine Learning

Match Group

Palo Alto, California, United States (Hybrid)
9 Months ago
Philips - Principal Catheter NPI R&D Engineer

Philips

San Diego, California, United States (On-Site)
2 Months ago

Get notifed when new similar jobs are uploaded

Similar Skill Jobs

Glean - Delivery Excellence Manager

Glean

New York, United States (Hybrid)
4 Weeks ago
Go Fund Me - Senior Principal Business Operations

Go Fund Me

(Remote)
2 Months ago
bytedance - Music Product Counsel - Global Legal

bytedance

San Jose, California, United States (On-Site)
9 Months ago
Click Therapeutics - Senior Business Development Manager/Associate Business Development Director

Click Therapeutics

New York, United States (Hybrid)
2 Months ago
Dream Sports - SDE3 - Full Stack Developer

Dream Sports

Mumbai, Maharashtra, India (On-Site)
9 Months ago
Critical mass - Freelance Senior Designer

Critical mass

Vancouver, British Columbia, Canada (On-Site)
2 Months ago
Qualcomm - Senior SoC/RTL Design Engineer

Qualcomm

San Diego, California, United States (On-Site)
1 Month ago
Twitch - Data Scientist

Twitch

San Francisco, California, United States (On-Site)
2 Months ago
Aeries technology - Project Manager

Aeries technology

Bengaluru, Karnataka, India (On-Site)
1 Month ago

Get notifed when new similar jobs are uploaded

Jobs in United States

Christ Fellowship - Audio Engineer

Christ Fellowship

Florida, United States (On-Site)
2 Months ago
Unity - Manager, Software Engineering, Web Platform

Unity

United States (Remote)
2 Months ago
Zscaler - Senior Staff Software Engineer - API Tooling and Frameworks

Zscaler

San Jose, California, United States (On-Site)
4 Weeks ago
Advanced Systems Group, LLC - Social Media Effects Developer

Advanced Systems Group, LLC

United States (Remote)
1 Month ago
Vercel - Software Engineer, Monetization

Vercel

San Francisco, California, United States (Hybrid)
2 Months ago
Whatnot - Quality Assurance Lead, Trust & Risk

Whatnot

Los Angeles, California, United States (On-Site)
3 Months ago
Rippling - Senior Staff Software Engineer - Time Products

Rippling

San Francisco, California, United States (On-Site)
1 Month ago
GoMotive - Senior Manager, FP&A

GoMotive

United States (Remote)
4 Weeks ago
Super.com - Senior Product Designer

Super.com

United States (Remote)
2 Months ago
Ziff Davis - Partner Account Manager

Ziff Davis

United States (Remote)
1 Month ago

Get notifed when new similar jobs are uploaded

Research Development Jobs

Joyteractive - Market Research Analyst

Joyteractive

Poland (Remote)
4 Months ago
Ubisoft - R&D Engineer

Ubisoft

Pune, Maharashtra, India (Hybrid)
1 Month ago
Playstation - Senior User Experience Researcher

Playstation

Montreal, Quebec, Canada (On-Site)
1 Month ago
Apple - ML Engineering Manager, Siri

Apple

Cupertino, California, United States (On-Site)
1 Month ago
bytedance - Research Scientist Graduate (Foundation Model - Vision and Language)

bytedance

Seattle, Washington, United States (On-Site)
3 Months ago
Ansys - R&D Engineer II - Desktop AI/ML

Ansys

Vancouver, British Columbia, Canada (Hybrid)
2 Months ago
luxsoft - Python Developer with AI

luxsoft

India (Remote)
1 Month ago
mad finger games - Lead AI Programmer

mad finger games

Brno, South Moravian Region, Czechia (On-Site)
2 Months ago
Match Group - Software Engineer III, Machine Learning Trust and Safety

Match Group

Palo Alto, California, United States (Hybrid)
2 Months ago

Get notifed when new similar jobs are uploaded