Backend Software Engineer (Senior)

Mercor
San Francisco, CA

About Mercor

Mercor is training models that predict how well someone will perform on a job better than a human can. We use our platform to source, vet, and onboard expert contractors who help train AI models in a wide variety of domains. Our technology is so effective it’s used by all of the top 5 AI labs.
We scaled from $1–500M in revenue run rate in the last 17 months, making us the fastest growing company in the world. Our growth is accelerating: 11% week-over-week in July, 18% in August, and 19% in September. The team is small, profitable, and growing as fast as we can hire exceptional people.

About the Role

As a Senior Software Engineer at Mercor, you’ll take end-to-end ownership of complex projects that power the workflows of the world’s leading AI companies. You’ll architect and scale distributed systems, mentor other engineers, and set technical direction for high-impact initiatives. This role goes beyond coding: you’ll help shape engineering culture, influence product decisions, and ensure our systems scale in lockstep with our hyper-growth.

What You’ll Do

  • Design, build, and scale production-grade backend APIs, services, and infrastructure.

  • Take ownership of system design and architecture decisions that impact core workflows.

  • Mentor and support junior engineers through code reviews, pair programming, and design discussions.

  • Partner with Product and Design to deliver features quickly without sacrificing quality or scalability.

  • Anticipate technical bottlenecks, propose solutions, and drive initiatives that increase reliability.

  • Contribute to the systems that enable OpenAI, Anthropic, Google, and others to train and evaluate their models.

What We’re Looking For

  • Strong coding fundamentals in Python (our primary backend), though interviews are language-agnostic.

  • Deep understanding of distributed systems, scalability challenges, and system design.

  • Experience shipping production systems at scale in high-growth or high-stakes environments.

  • Ability to reason about trade-offs and make decisions balancing speed and reliability.

  • Strong communication skills with an ability to align technical and business goals.

  • Bias toward ownership, curiosity, and delivering simple solutions to complex problems.

Why Mercor

  • Impact: Your work powers how the world’s leading AI labs train and test their models.

  • Learning: Get early insights into frontier model capabilities months before the market.

  • Growth: Work on both infrastructure and research-adjacent projects with fast paths to ownership.

Posted 2026-02-13

Recommended Jobs

PT Sales Associate - Century City

REISS
California

What’s the role about? As part of our team, you’ll be joining our new store opening in Century City on a part-time basis, as our Sales Associate, who is responsible for providing exceptional custom…

View Details
Posted 2026-03-24

Emergency Food Assistance Program Coordinator

Jacobs & Cushman San Diego Food Bank
San Diego, CA

The Jacobs & Cushman San Diego Food Bank is currently hiring for a hiring for a full-time, hourly, non-exempt and benefited, Emergency Food Assistance Program Coordinator at our Miramar location. …

View Details
Posted 2026-03-22

Sales Manager

Ontario, CA

Job Schedule Corporate Retail Store Job ID 75444 Sales Manager The salary range for this role is $20.00 to $23.00 per hour/annually.* This position is also eligible for incentive pay based on …

View Details
Posted 2026-03-30

Sr. Distinguished, Data Engineer - Enterprise Data Storage and Consumption Platforms Data Engineer

Capital One Financial Corporation
San Francisco, CA

Sr. Distinguished, Data Engineer - Enterprise Data Storage and Consumption Platforms Data Engineer Distinguished Data Engineers are individual contributors who strive to be diverse in thought…

View Details
Posted 2026-03-10

Private Banker - Strategic Wealth & Liquidity Solutions (Tech & Healthcare) - Director

Citi
San Francisco, CA

About Wealth At Work: Enterprise Citi Wealth at Work division is dedicated to empowering individuals and families associated with leading corporations and to achieve their financial aspirations. W…

View Details
Posted 2026-02-15

Mammography Technologist II (PRN)

Houston Methodist
Cypress, CA

At Houston Methodist, the Mammography Technologist II position is an experienced Technologist who completes a variety of routine and specialized mammograms and completes quality controls as needed. T…

View Details
Posted 2026-02-24

Accounts Receivable Specialist I

Western Health Advantage
Sacramento, CA

Summary Description: The Accounts Receivable Specialist I is responsible for maintaining the accuracy of Western Health Advantage’s accounts receivable. This includes maintenance over account ba…

View Details
Posted 2026-03-07

Laundry Supervisor - Housekeeping (Full Time)

Terranea Resorts
Rancho Palos Verdes, CA

Overview: Supervise, train and inspect the performance of assigned laundry attendants on all procedures are completed to the hotel`s standards. Assists where necessary to ensure optimum service to em…

View Details
Posted 2026-01-27

HR Assistant to Chief of Staff

Bask Health
Los Angeles, CA

We’re looking for an organized, detail-oriented HR Assistant to support our Chief of Staff at a fast growing startup. The role will be focused on helping with HR function with day-to-day administrati…

View Details
Posted 2026-01-16

Staff Salesforce Developer

Nutanix
San Jose, CA

Hungry, Humble, Honest, with Heart.   The Opportunity Are you a skilled Salesforce developer with a strong foundation in Lightning Web Components and Apex, who thrives in collaborative envir…

View Details
Posted 2026-03-22