Principal Software Engineer

At ZestFinance, we’re changing the way finance works, from how people borrow money to the way that credit decisions are made.

We’re looking for an experienced Principal Software Engineer to help define the technical direction of our lending business. You are passionate about building amazing services with cutting edge technologies in a lean and fast environment. You want to join an organization where engineers are recognized and respected for their technical leadership.

You will be joining a team of 30+ highly-skilled full stack engineers where you will be contributing your software design and systems development skills. You will have the opportunity to improve team efficiency and productivity by setting high quality engineering standards. This is a hands-on position, and you will have many opportunities to pair with junior and senior developers, delivering features while reinforcing engineering best practices.

We practice pairing and TDD in a Ruby on Rails (RoR) environment with an AngularJS + Rails + MySQL stack. We use Docker for containerization and deployments. Our data warehouse / reporting stack is S3 / RedShift / Looker based. It’s not required that you have experience with these technologies; rather, Zest is looking for someone who can learn quickly as technologies change rapidly.


  • Mentoring and pairing effectively with other developers, delivering high-quality code, code reviews.
  • Innovating technical design and systems architecture across services and applications.
  • Establishing and reinforcing engineering philosophies and company culture.
  • Participating in the hiring process to grow our engineering team with an ever-rising quality bar.
  • Strengthening, execution, and delivery of the ZestFinance product roadmap.
  • Increasing team skill level in areas of software design and systems architecture.
  • Improving team efficiency and productivity with process improvement ideas .


  • 8+ years experience in a senior developer or architect role.
  • Hands-on coding experience in Ruby, Python, or similar.
  • TDD/BDD methodologies and testing frameworks including RSpec.
  • Common internet technologies (e.g. CSS, HTML, JavaScript) with an emphasis on frameworks like backbone.js or AngularJS.
  • Experience designing APIs adhering to the REST architecture style.
  • Ability to analyze and troubleshoot large-scale distributed systems (network analysis, performance and application issues).
  • Continuous integration tools (e.g. Github, Travis CI, Jenkins).
  • Amazon Web Services, e.g. EC2, RDS, S3, and Route53.
  • Monitoring/alerting tools (e.g. New Relic, Airbrake, PagerDuty).
  • Docker for provisioning servers and deploying applications/services.
  • Excellent verbal and written communication skills including the ability to explain technical issues to a non-technical audience.
  • Strong work ethic and a can-do attitude.
  • B.S. in Computer Science or equivalent experience.


ZestFinance is a technology startup that uses machine learning and large-scale data analysis to transform credit availability for millions of Americans. Over the past 5 years, ZestFinance has built a big data underwriting technology that more accurately predicts likelihood of repayment.  ZestFinance uses this technology to make loans to customer that banks typically overlook.  ZestFinance also licenses its technology to other companies, including in China.  

ZestFinance was founded in September, 2009, by founder and CEO Douglas Merrill, an accomplished technology executive who previously served as CIO of Google.  

We are committed to diversity in hiring, professional development, and everyday discussion.  Zest is determined to hire crazy smart people who are different from each other to create broad thinking, lots of different ideas, and by extension, the best team possible.


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