Senior JavaScript Performance Engineer

  • San Francisco, CA, USA
  • Full-time
  • Department: Engineering

Company Description

Optimizely is the world's leader in customer experience optimization, allowing businesses to dramatically drive up the value of their digital products, commerce and campaigns through its best in class experimentation software platform. By replacing digital guesswork with evidence-based results, Optimizely enables product and marketing professionals to accelerate innovation, lower the risk of new features, and drive up the return on investment from digital by up to 10X. Over 26 of the Fortune 100 companies choose Optimizely to power their global digital experiences. Optimizely’s impressive customer list includes eBay, FOX, IBM, The New York Times and many more global enterprises.

Job Description

We're looking for a Senior Performance-focused Javascript Engineer to join our Web Delivery team.  As a member of this team, you'll be working with the latest in web technologies to enable some of the world’s largest companies—including over 24 of the Fortune 100—to deliver highly performant digital experiences that delight customers through the use of Optimizely experiments, personalization and feature management.

We’ve assembled a small team of cross-functional engineers to tackle the problem of web performance for our customers, seeking to improve both the speed of delivery of our experimentation JavaScript platform as well as the runtime performance of the product in the browser. As an engineer on this team, you will be working on low level JavaScript and using best-of-breed tools for packaging, testing, and delivering code to high-traffic web environments. If the idea of cutting milliseconds off load and paint timings interests you more than building fancy UI’s in React or Angular you're in the right place. If the prospect of the new shiny webpack plugin that shaves off a few milliseconds or the new CDN based edge workers bringing things closer to the end user, or diving deep into Chrome source code to find the trick to make the website load fast gets you up in the morning, we want to talk to you!

What You’ll Do

  • Drive new features and enhancements from initial design to finished product.
  • Develop and implement performance tests and experiments to evaluate new features and find ways to speed up our existing product.
  • Collaborate closely with other software engineers, product managers, and customers.
  • Collaborate with other engineers on the team via mentorship, pair programming, and code reviews
  • Help define our product vision, by prototyping new, more performant approaches for our award-winning experimentation platform.


  • You have 5+ years of professional coding experience with a focus on JavaScript-based development.
  • You're an expert in modern web development techniques, especially performance analysis.
  • You have familiarity with a modern web UI framework or two.
  • You've experimented with build tools, and know how to squeeze more juice out of them than what comes pre-configured.
  • You're willing and able to contribute anywhere in the stack and wear multiple hats
  • You're excited about mentoring other engineers and helping them write more performant code.

Additional Information



  • Commuter and transportation benefits
  • Catered in-office lunch and dinner on weekdays
  • Full medical insurance with very low co-pay and deductible. HMO, PPO, and HSA options available
  • Full dental coverage including orthodontics
  • Full vision coverage including contacts
  • Dependents 100% covered for medical, dental, and vision
  • Wellness Grant
  • Unlimited vacation policy and seventeen weeks of paid parental leave
  • 401k benefit
  • Working with a great team and having a huge impact!


At Optimizely, we embody inclusion and embrace diversity.  Optimizely is an equal opportunity employer and makes employment decisions on the basis of merit.  Optimizely prohibits discrimination based on race, color, religion, sex, sexual identity, gender identity, marital status, veteran status, nationality, citizenship, age, disability, medical condition, pregnancy, or any other unlawful consideration. All your information will be kept confidential according to EEO guidelines.


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