Principal Software Engineer, Machine Learning Simulations

About Upstart

At Upstart, we're united by a mission that matters: to radically reduce the cost and complexity of borrowing for all Americans. Every day, we bring creativity, experimentation, and advanced AI to reshape access to credit, helping millions move forward financially with clarity and confidence.

As the leading AI lending marketplace, we partner with banks and credit unions to expand access to affordable credit through technology that's both radically intelligent and deeply human. Our platform runs over one million predictions per borrower using more than 1,800 signals, powering smarter, fairer decisions for millions of customers. But the numbers only hint at the impact. Every idea, every voice, and every contribution moves us closer to a world where credit never stands between people and their financial progress.

We're proudly digital-first, giving most Upstarters the flexibility to do their best work from wherever they thrive, alongside teammates across 80+ cities in the US and Canada. Digital-first doesn't mean distant. We're intentional about in-person connection through team onsites, planning sessions, and moments that spark creativity and trust. And whether you choose to work primarily from home or collaborate in-person from one of our offices in Columbus, Austin, the Bay Area, or New York City (opening Summer 2026), you'll have the support to work in the way that works best for you.

If you're energized by tackling meaningful problems, excited to innovate with purpose, and motivated by work that truly matters, we'd love to hear from you.

The Team:

The Machine Learning & Simulations Platform (MLSP) team builds and operates the core infrastructure that powers ML model training, inference, and marketplace simulation at Upstart. Our platform is foundational to the company's success-every underwriting, fraud, conversion, and verification model runs here. We also provide the simulation capabilities that help teams experiment safely and assess business impact without requiring costly live experimentation.

We are on a mission to reimagine our infrastructure to support the growing complexity of our ML models, the demand for low-latency inference, and the accuracy needed to simulate the dynamics of our borrower-lender marketplace at scale. The team partners closely with Engineering, ML, Product, and Finance to accelerate innovation while safeguarding performance and integrity.

As a Principal Software Engineer focused on Machine Learning Simulations at Upstart, you will be responsible for building an MLOps platform to support machine learning model inference, process automation, model deployment, and observability. Machine Learning is critical to Upstart's core business, and our greatest competitive advantage lies in the fact that we're able to innovate on our AI engine quickly. You will also help build a marketplace simulation platform to support rapid innovation across ML and Finance teams.

How you'll make an impact

• Build, maintain, and optimize Upstart's next-generation machine learning and simulation platform, enabling increased scale, performance, and confidence in decisioning
• Develop high-quality software applications that enable machine learning models to be applied to the ever-evolving needs of the business
• Enable the modernization of our serving infrastructure, reducing inference latency to just a few seconds for our most complex models
• Design and contribute to our simulation systems to more accurately reflect production environments, reducing simulation cost and enabling broader usage across teams
• Communicate closely with cross-functional partners from ML, Engineering, Product, and Data Engineering teams, keeping all stakeholders informed
• Mentor engineers across the team, sharing expertise on distributed systems, MLOps, and scalable architecture

Minimum Qualifications

• Bachelor's degree in Computer Science, Engineering, or Mathematics, or a related field (or its equivalent) + 8 years of experience
• Experience building or contributing to platforms or systems that support machine learning model simulation
• Experience building self-serve or configuration-driven tooling for internal stakeholders
• Experience building and maintaining backend software services and APIs
• Proficiency with some or more of the following: Python, Kotlin, Databricks, and AWS
• Exhibits a growth mindset - you're not afraid to pick up new technologies that are best for the task, and learn from others.
• Ability to quickly comprehend and reiterate complex requirements from product or engineering leadership and translate those to both technical and non-technical stakeholders
• Track record of successfully mentoring and developing other engineers around you while seeking out and appreciating constructive feedback

Preferred Qualifications

• Familiarity with model serving technologies like Ray, and experimentation frameworks
• Proficiency with Flask, FastAPI, Metaflow, MLflow, gRPC, Kafka, Spark/PySpark, ETL/ELT, Redshift (or similar)
• Excellent quantitative reasoning skills with interest in working at the intersection of engineering and machine learning
• Strong sense of ownership and accountability for the quality and timely delivery of work
• Proven ability to effectively analyze and solve complex problems
• Excellent written and verbal communication skills with stakeholders, peers and product owners
• Ability to thrive both in self-directed work environments and in collaborative settings, contributing positively to team dynamic

Position location This role is available in the following locations: Remote-US

Time zone requirements The team operates on the East/West coast time zones.

Travel requirements As a digital first company, the majority of your work can be accomplished remotely. The majority of our employees can live and work anywhere in the U.S but are encouraged to to still spend high quality time in-person collaborating via regular onsites. The in-person sessions' cadence varies depending on the team and role; most teams meet once or twice per quarter for 2-4 consecutive days at a time.

#LI-REMOTE

#LI-MidSenior

At Upstart, your base pay is one part of your total compensation package. The anticipated base salary for this position is expected to be within the below range. Your actual base pay will depend on your geographic location-with our "digital first" philosophy, Upstart uses compensation regions that vary depending on location. Individual pay is also determined by job-related skills, experience, and relevant education or training. Your recruiter can share more about the specific salary range for your preferred location during the hiring process.

In addition, Upstart provides employees with target bonuses, equity compensation, and generous benefits packages (including medical, dental, vision, and 401k).

United States | Remote - Anticipated Base Salary Range

$195,300-$270,400 USD

At Upstart, your base pay is one part of your total compensation package. The anticipated base salary for this position is expected to be within the below range. Your actual base pay will depend on your geographic location-with our "digital first" philosophy, Upstart uses compensation regions that vary depending on location. Individual pay is also determined by job-related skills, experience, and relevant education or training. Your recruiter can share more about the specific salary range for your preferred location during the hiring process.

In addition, Upstart provides employees with target bonuses, equity compensation, and generous benefits packages (including medical, dental, vision, and 401k).

Canada | Remote - Anticipated Base Salary Range

$182,800-$230,000 USD

What you'll love

At Upstart, our benefits are designed to support your health, financial well-being, family, and personal growth. Here's what you can expect:

• Competitive compensation, including base pay, bonus opportunities, and annual equity grants that vest quarterly
• Retirement benefits to help you plan for the future, including a 401(k) or Group Retirement Savings Plan with a company match of $2 for every $1 contributed, up to $15,000 annually (USD in the US, CAD in Canada)
• Employee Stock Purchase Plan (ESPP) with discounted stock purchase options for eligible employees (US only)
• Comprehensive health coverage designed to support you and your family, including medical, dental, vision, and wellness resources for US and supplemental health coverage for Canada.
• Health Savings Account contributions from Upstart for eligible plans (US only)
• Income protection benefits, including life insurance and disability coverage for added financial security
• Paid time off, sick leave, and company holidays, in line with local requirements
• Paid family and parental leave to support caregiving and major life moments (duration varies by country)
• Family-centered benefits to support fertility, parenthood, and caregiving needs
• Employee Assistance Program (EAP) offering mental health support and life-centered resources
• Financial wellness resources, including access to financial planning tools and a financial concierge service (US Only)
• Annual wellness allowance to support your physical and emotional well-being and personal development, based on what matters most to you
• Annual productivity allowance to invest in relevant tools and resources you need to do your best work, no matter where you work from
• Connection and community through team events, all-company updates, and employee resource groups (ERGs)
• Onsite perks, including catered lunches and fully stocked micro-kitchens when working from one of our offices in the Bay Area, Austin, Columbus, and New York City (opening Summer 2026!)

For roles based in Canada, please note that we are not currently able to hire in Quebec.

Upstart is a proud Equal Opportunity Employer. Just as we are dedicated to improving access to affordable credit for all, we are committed to inclusive and fair hiring practices.

If you require reasonable accommodation in completing an application, interviewing, completing any pre-employment testing, or otherwise participating in the employee selection process, please email View email address on click.appcast.io