Upwork Inc.’s (Nasdaq: UPWK) family of companies connects businesses with global, AI-enabled talent across every contingent work type including freelance, fractional, and payrolled. This portfolio includes the Upwork Marketplace, which connects businesses with on-demand access to highly skilled talent across the globe, and Lifted, which provides a purpose-built solution for enterprise organizations to source, contract, manage, and pay talent across the full spectrum of contingent work. From Fortune 100 enterprises to entrepreneurs, businesses rely on Upwork Inc. to find and hire expert talent, leverage AI-powered work solutions, and drive business transformation. With access to professionals spanning more than 10,000 skills across AI & machine learning, software development, sales & marketing, customer support, finance & accounting, and more, the Upwork family of companies enables businesses of all sizes to scale, innovate, and transform their workforces for the age of AI and beyond.

Since its founding, Upwork Inc. has facilitated more than $30 billion in total transactions and services as it fulfills its purpose to create opportunity in every era of work. Learn more about the Upwork Marketplace at Upwork.com and follow us on LinkedIn, Facebook, Instagram, TikTok, and X; and learn more about Lifted at Go-Lifted and follow on LinkedIn.

Search & Recommendations sits at the center of how work happens on Upwork. In this role, you will lead the engineering organization responsible for building the systems that connect millions of clients and freelancers across the globe. You will shape the future of Upwork’s matching platform by setting technical direction, scaling core systems, and delivering experiences that power everything from search and browse to conversational matching, agentic workflows, and emerging AI-native surfaces. This is a high-impact leadership opportunity to guide a strong engineering team while partnering closely with product, machine learning, and executive leadership on a platform central to Upwork’s long-term growth.

Responsibilities

• Define and drive the technical strategy for Upwork’s Search & Recommendations platform, aligning engineering investments with long-term business goals, marketplace performance, and platform scalability.
• Lead, grow, and develop a high-performing organization of software and machine learning engineers, fostering a culture of ownership, inclusion, high standards, and continuous learning.
• Deliver a unified Search & Recommendations platform that powers matching experiences across client and talent journeys, including search, recommendations, conversational experiences, and agentic workflows.
• Modernize search infrastructure by guiding the migration from legacy systems to scalable, maintainable, and high-performance architectures with clear APIs, observable pipelines, and strong experimentation support.
• Partner closely with product, ML, data science, design, and senior leadership to prioritize roadmaps, navigate tradeoffs, and translate complex platform decisions into measurable business outcomes.
• Champion engineering excellence through strong practices in system reliability, latency, data integrity, responsible AI development, and operational health across critical marketplace systems.
• Establish clear operating mechanisms, metrics, and team rhythms that improve execution, support long-range planning, and track platform health, engineering effectiveness, and business impact.

What It Takes to Catch Our Eye

• Significant experience leading engineering teams in high-scale environments, with a strong track record of delivering search, recommendations, ranking, or retrieval systems that drive meaningful business results.
• Deep technical fluency in distributed systems, data pipelines, search architecture, and modern machine learning infrastructure, with the ability to guide architecture decisions and mentor senior engineers and managers.
• Proven success leading integrated teams of software engineers and machine learning engineers while building strong partnerships across product, data science, and executive stakeholders.
• Ability to operate effectively at multiple altitudes, translating technical depth into strategic clarity and making sound decisions in ambiguous, fast-moving environments.
• Strong applied understanding of AI-native engineering workflows, including using AI to accelerate design, experimentation, and delivery while ensuring technical accuracy, responsible use, and scalable team adoption.

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 Company is committed to conducting an individualized assessment and giving all individuals a fair opportunity to provide relevant information or context before making any final employment decision.

We use BrightHire, an AI-enabled tool, to record interviews and summarize interview transcripts. The tool allows the interviewer to focus on the discussion and does not score or evaluate candidates or make recommendations. The interview transcripts are reviewed, and decisions are only made by humans. Candidates who prefer not to have their interview recorded through BrightHire can opt out when the interview is scheduled.

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.

Upwork Inc.’s (Nasdaq: UPWK) family of companies connects businesses with global, AI-enabled talent across every contingent work type including freelance, fractional, and payrolled. This portfolio includes the Upwork Marketplace, which connects businesses with on-demand access to highly skilled talent across the globe, and Lifted, which provides a purpose-built solution for enterprise organizations to source, contract, manage, and pay talent across the full spectrum of contingent work. From Fortune 100 enterprises to entrepreneurs, businesses rely on Upwork Inc. to find and hire expert talent, leverage AI-powered work solutions, and drive business transformation. With access to professionals spanning more than 10,000 skills across AI & machine learning, software development, sales & marketing, customer support, finance & accounting, and more, the Upwork family of companies enables businesses of all sizes to scale, innovate, and transform their workforces for the age of AI and beyond.

Since its founding, Upwork Inc. has facilitated more than $30 billion in total transactions and services as it fulfills its purpose to create opportunity in every era of work. Learn more about the Upwork Marketplace at Upwork.com and follow us on LinkedIn, Facebook, Instagram, TikTok, and X; and learn more about Lifted at Go-Lifted and follow on LinkedIn.

Sr. Lead AI Research Scientist, AI Evaluation and Reliability

The AI Foundations team leads core research and development across the training, evaluation, and deployment of AI systems that power Uma, Upwork’s flagship AI model, and other customer-facing generative AI capabilities. As a Sr. Lead AI Research Scientist focused on AI Evaluation and Reliability, you will drive high-impact research initiatives that improve the trustworthiness, robustness, and real-world performance of AI systems operating at marketplace scale.

At the Sr. Lead level, this role combines deep technical expertise with cross-functional leadership. You will identify and lead research efforts that address systemic reliability challenges, partner closely with engineering and product teams to translate research into production outcomes, and help shape how Upwork evaluates AI performance in real work scenarios. Your work will support AI systems embedded in retrieval-based workflows, agentic architectures, and human plus AI collaboration patterns, while contributing to Upwork’s broader AI research strategy and external presence.

Responsibilities:

• Lead applied research initiatives focused on AI evaluation, reliability, and robustness, defining success metrics tied to customer impact and production readiness.

• Design and validate methods to measure and mitigate AI reliability risks, including uncertainty estimation, hallucination detection, and identification of model failure modes.

• Partner cross-functionally with engineering, data science, and product teams to integrate research outcomes into customer-facing AI systems and workflows.

• Own research projects end to end, from problem framing and hypothesis development through experimentation, prototyping, and synthesis of results.

• Influence technical direction across teams by surfacing insights, proposing scalable solutions, and aligning stakeholders on priorities and tradeoffs.

• Mentor researchers and engineers through technical guidance, feedback, and collaborative leadership on shared initiatives.

• Contribute to Upwork’s external research footprint through publications, presentations, and engagement with the broader AI research community.

What it takes to catch our eye:

• Proven experience leading applied AI research that balances scientific rigor with real-world deployment constraints and business impact.

• A strong record of research contribution through publications, internal innovation, or demonstrable influence on production AI systems.

• Deep proficiency with Python and modern deep learning frameworks such as PyTorch, with hands-on experience evaluating and improving large-scale models.

• An adaptive approach to integrating AI tools into research and development workflows to accelerate experimentation, improve evaluation quality, and share best practices with others.

• A collaborative, growth-oriented mindset with the ability to mentor peers, communicate complex ideas clearly, and thrive in a fast-evolving, bottom-up environment.
  
  

Come change how the world works.

Upwork is establishing an operational hub in Toronto, Canada. The new office is expected to be fully operational by Q4 2026. This role will require 3 days in office once we have an office open.

This position will initially be employed through a partner to ensure a seamless hiring process while we establish the hub. Once the hub is established, there may be opportunities to transition to employment with Upwork, depending on business needs and other requirements. While employed by the partner, you’ll work as part of Upwork’s team, with access to our resources, culture, and growth opportunities.

Our partner will offer competitive benefits. When Upwork’s hub is established, we will be excited to offer employment and benefits directly as business needs require. 

Upwork is committed to building a diverse, inclusive, and equitable workforce. Employment decisions are made without regard to race, color, religion, gender, sexual orientation, gender identity, national origin, disability, or any other status protected by applicable law.

We use BrightHire, an AI-enabled tool, to record interviews and summarize interview transcripts. The tool allows the interviewer to focus on the discussion and does not score or evaluate candidates or make recommendations. The interview transcripts are reviewed, and decisions are only made by humans. Candidates who prefer not to have their interview recorded through BrightHire can opt out when the interview is scheduled.

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 and the Applicant Privacy Addendum (Canada).

Upwork Inc.’s (Nasdaq: UPWK) family of companies connects businesses with global, AI-enabled talent across every contingent work type including freelance, fractional, and payrolled. This portfolio includes the Upwork Marketplace, which connects businesses with on-demand access to highly skilled talent across the globe, and Lifted, which provides a purpose-built solution for enterprise organizations to source, contract, manage, and pay talent across the full spectrum of contingent work. From Fortune 100 enterprises to entrepreneurs, businesses rely on Upwork Inc. to find and hire expert talent, leverage AI-powered work solutions, and drive business transformation. With access to professionals spanning more than 10,000 skills across AI & machine learning, software development, sales & marketing, customer support, finance & accounting, and more, the Upwork family of companies enables businesses of all sizes to scale, innovate, and transform their workforces for the age of AI and beyond.

Since its founding, Upwork Inc. has facilitated more than $30 billion in total transactions and services as it fulfills its purpose to create opportunity in every era of work. Learn more about the Upwork Marketplace at Upwork.com and follow us on LinkedIn, Facebook, Instagram, TikTok, and X; and learn more about Lifted at Go-Lifted and follow on LinkedIn.

We’re seeking a Senior Lead Machine Learning Engineer to architect, ship, and scale the next generation of agentic intelligence across Upwork. You will lead end‑to‑end development of AI agents and the platform that powers them—from LLM training and evaluation to runtime orchestration, safety, and developer APIs. This is a hands‑on, high‑impact role at the intersection of applied research and platform engineering, enabling internal teams and external developers to build reliable, safe, and high‑performing agents on Upwork.

Responsibilities

• Build Agentic Intelligence.  Design and implement multi‑agent systems (planning, tool‑use, memory, debate/critique, reflection) with robust guardrails and recovery strategies.
• Develop protocol‑aware agents and services that interoperate cleanly with developer tooling (e.g., agent frameworks and protocols such as MCP). 
• Own reliability at scale: deterministic execution where needed, idempotency, timeouts/retries, and evaluation‑driven iteration on agent behavior.
• Train, Align, and Evaluate LLMs for Agents.  Lead data strategy and curation for agent tasks; drive SFT, DPO, RLHF/RLAIF, and safety tuning tailored to multi‑tool, multi‑step workflows.
• Stand up evaluation harnesses for functional, task, and longitudinal metrics (success rate, time‑to‑completion, hallucination/escape rates, cost/latency).
• Build policy‑driven guardrails; partner with Legal/Security on data governance and privacy.
• Engineer Agentic Platform Backend Infrastructure.  Architect low‑latency inference, retrieval, and orchestration services (streaming, event‑driven pipelines; scalable queues; caching; batching) with strong SLOs.
• Ship production‑grade services (APIs/SDKs, auth, rate limiting, observability) that make agent features easy to integrate for internal and external developers. 
• Optimize cost/performance via quantization, distillation, model‑routing, and autoscaling; integrate evaluation signals directly into runtime and CI/CD.
• Lead, Partner, and Uplevel the Ecosystem.  Provide technical leadership across research, product, and platform teams; mentor senior ICs; influence roadmaps with clear metrics and trade‑offs.
• Publish internal guidance and exemplar implementations; contribute to technical content, samples, and reference architectures for our agent platform. 
• Define and track KPIs for data/quality/throughput, and drive continuous improvement using experiment results and production telemetry.

What it takes to catch our eye

• 8–12+ years in applied ML/ML systems with 4+ years building LLM‑powered products; proven delivery of agentic workflows in production.
• Hands‑on mastery of LLM adaptation (prompting, tool/function calling), data curation, and safety/guardrails.
• Strong software fundamentals (distributed systems, transactions, consistency, resiliency) and experience building high‑throughput microservices/APIs/SDKs.
• Fluency with Python; proficiency in one of Go/Java/Javascript a plus. Experience with container orchestration, messaging/streaming, and observability stacks.
• Experience designing eval suites for agents (task/rubric‑based, offline/online) and closing the loop from evals → training → runtime policy.
• Comfort with cost, latency, and reliability trade‑offs; you use metrics to make crisp decisions under ambiguity.
• Familiarity with agent frameworks and protocols (e.g., MCP; API/SDK design for developer productivity).
• Track record of leading cross‑functional initiatives and mentoring senior engineers; excellent written communication and bias for measurable results.

Come change how the world works.

This position will initially be employed through a partner to ensure a seamless hiring process while we establish the hub. Once the hub is established, there may be opportunities to transition to employment with Upwork depending on business needs and other requirements. While employed by the partner, you’ll work as part of Upwork’s team, with access to our resources, culture, and growth opportunities.

Upwork Inc.’s (Nasdaq: UPWK) family of companies connects businesses with global, AI-enabled talent across every contingent work type including freelance, fractional, and payrolled. This portfolio includes the Upwork Marketplace, which connects businesses with on-demand access to highly skilled talent across the globe, and Lifted, which provides a purpose-built solution for enterprise organizations to source, contract, manage, and pay talent across the full spectrum of contingent work. From Fortune 100 enterprises to entrepreneurs, businesses rely on Upwork Inc. to find and hire expert talent, leverage AI-powered work solutions, and drive business transformation. With access to professionals spanning more than 10,000 skills across AI & machine learning, software development, sales & marketing, customer support, finance & accounting, and more, the Upwork family of companies enables businesses of all sizes to scale, innovate, and transform their workforces for the age of AI and beyond.

Since its founding, Upwork Inc. has facilitated more than $30 billion in total transactions and services as it fulfills its purpose to create opportunity in every era of work. Learn more about the Upwork Marketplace at Upwork.com and follow us on LinkedIn, Facebook, Instagram, TikTok, and X; and learn more about Lifted at Go-Lifted and follow on LinkedIn.

We’re seeking a Senior Lead Machine Learning Engineer to architect, ship, and scale the next generation of agentic intelligence across Upwork. You will lead end‑to‑end development of AI agents and the platform that powers them—from LLM training and evaluation to runtime orchestration, safety, and developer APIs. This is a hands‑on, high‑impact role at the intersection of applied research and platform engineering, enabling internal teams and external developers to build reliable, safe, and high‑performing agents on Upwork.

Responsibilities

• Build Agentic Intelligence.  Design and implement multi‑agent systems (planning, tool‑use, memory, debate/critique, reflection) with robust guardrails and recovery strategies.
• Develop protocol‑aware agents and services that interoperate cleanly with developer tooling (e.g., agent frameworks and protocols such as MCP). 
• Own reliability at scale: deterministic execution where needed, idempotency, timeouts/retries, and evaluation‑driven iteration on agent behavior.
• Train, Align, and Evaluate LLMs for Agents.  Lead data strategy and curation for agent tasks; drive SFT, DPO, RLHF/RLAIF, and safety tuning tailored to multi‑tool, multi‑step workflows.
• Stand up evaluation harnesses for functional, task, and longitudinal metrics (success rate, time‑to‑completion, hallucination/escape rates, cost/latency).
• Build policy‑driven guardrails; partner with Legal/Security on data governance and privacy.
• Engineer Agentic Platform Backend Infrastructure.  Architect low‑latency inference, retrieval, and orchestration services (streaming, event‑driven pipelines; scalable queues; caching; batching) with strong SLOs.
• Ship production‑grade services (APIs/SDKs, auth, rate limiting, observability) that make agent features easy to integrate for internal and external developers. 
• Optimize cost/performance via quantization, distillation, model‑routing, and autoscaling; integrate evaluation signals directly into runtime and CI/CD.
• Lead, Partner, and Uplevel the Ecosystem.  Provide technical leadership across research, product, and platform teams; mentor senior ICs; influence roadmaps with clear metrics and trade‑offs.
• Publish internal guidance and exemplar implementations; contribute to technical content, samples, and reference architectures for our agent platform. 
• Define and track KPIs for data/quality/throughput, and drive continuous improvement using experiment results and production telemetry.

What it takes to catch our eye

• 8–12+ years in applied ML/ML systems with 4+ years building LLM‑powered products; proven delivery of agentic workflows in production.
• Hands‑on mastery of LLM adaptation (prompting, tool/function calling), data curation, and safety/guardrails.
• Strong software fundamentals (distributed systems, transactions, consistency, resiliency) and experience building high‑throughput microservices/APIs/SDKs.
• Fluency with Python; proficiency in one of Go/Java/Javascript a plus. Experience with container orchestration, messaging/streaming, and observability stacks.
• Experience designing eval suites for agents (task/rubric‑based, offline/online) and closing the loop from evals → training → runtime policy.
• Comfort with cost, latency, and reliability trade‑offs; you use metrics to make crisp decisions under ambiguity.
• Familiarity with agent frameworks and protocols (e.g., MCP; API/SDK design for developer productivity).
• Track record of leading cross‑functional initiatives and mentoring senior engineers; excellent written communication and bias for measurable results.

Come change how the world works.

Upwork is establishing its first international operational hub in Lisbon, Portugal. The new office is expected to be fully operational by Q4 2026.This position will initially be employed through a partner to ensure a seamless hiring process while we establish the hub. Once the hub is established, there may be opportunities to transition to employment with Upwork depending on business needs and other requirements. While employed by the partner, you’ll work as part of Upwork’s team, with access to our resources, culture, and growth opportunities. Our partner will offer competitive benefits. When Upwork’s hub is established, we will be excited to offer employment and benefits directly as business needs require. Upwork is committed to building a diverse, inclusive, and equitable workforce. Employment decisions are made without regard to race, color, religion, gender, sexual orientation, gender identity, national origin, disability, or any other status protected by applicable law.