Senior Experiment Engineer

About Cro Metrics

At Cro Metrics, we’re on a mission to redefine growth for organizations and brands through unparalleled digital experiences that inspire action and deliver results. With transformative experimentation as our guide, we bridge bold ideas with practical solutions to create lasting impact.

We are a growth optimization agency that partners with mission-driven and high-growth companies to scale through data-driven experimentation. Our expertise spans A/B testing, personalization, and full-funnel digital strategy, empowering clients to make smarter decisions that drive measurable results.

Our fully remote team of strategists, analysts, engineers, and designers works across industries including eCommerce, fintech, nonprofit, and hospitality. We believe in autonomy, collaboration, and innovation as we help our clients grow smarter and faster.

The Role

Experimentation engineering is where good ideas stop being opinions and start being answers. As a Senior Experiment Engineer, you're the person who makes that happen, shipping the tests that decide how some of the most recognizable brands on the internet grow, convert, and keep their customers coming back.

You'll build experiments across the full complexity spectrum, including on frameworks and platforms you've never touched before. You'll sit directly with clients, help them turn fuzzy business questions into sharp, testable hypotheses, and then build the thing that proves or disproves them, cleanly, quickly, and without leaving a mess behind. You'll raise the bar for the engineers around you through code review, mentorship, and the occasional strong opinion, and you'll have a real voice in how we practice experimentation as a craft.

If you're the kind of engineer who gets energized by a new codebase, enjoys the translation between "messy business problem" and "clean technical solution," and wants your work tied to outcomes you can actually watch move, you'll fit right in here.

What You’ll Do

Build and ship experiments that hold up

• Develop experimentation across the full complexity spectrum, from straightforward A/B tests to experiments on unfamiliar frameworks, bespoke client stacks, and single-page applications you’re encountering for the first time.

• Review teammates’ code for the balance between over- and under-engineering, catching code that is brittle, indeterminate, or otherwise unreliable before it reaches a client’s site.

• Advise other engineers on best practices and advocate for our engineering standards and push for their adoption across the team.

• Own delivery so we hit our assigned targets on time, every time.

Partner directly with clients

• Partner with clients to identify experimentation challenges, design tailored technical solutions, and articulate their value in a way that builds confidence and advances the engagement.

• Communicate clearly and confidently with clients and account teams,setting expectations, addressing concerns, and reinforcing trust throughout the engagement.

• Translate complex technical concepts into plain language so clients and account teams can make informed decisions quickly.

Level up the practice

• Actively mentor colleagues on both technical craft and client-facing communication, helping them grow into well-rounded contributors.

• Devise and develop new solutions to recurring experimentation challenges, document them, and drive awareness and adoption across the engineering team.

• Run Sales Feasibility studies, produce sales intel deliverables, and consult the team on your findings to help win and scope the right kind of work.

• Keep learning to stay current on the CRO platform landscape and internal practices, and, frankly, nerd out over the engineering craft.

What You Bring

• Senior-level proficiency with HTML, SCSS, and JavaScript, including hands-on experience building experiments inside Single Page Applications (React, Vue, Angular, or similar).

• Production experience shipping experiments on one or more leading web experimentation platforms (e.g., Optimizely, VWO, Convert, AB Tasty, LaunchDarkly, Kameleoon, or equivalent).

• Fluent command of the command line, Git, and version control workflows in a collaborative team environment.

• A proven ability to accurately estimate complexity, assess feasibility, and communicate trade-offs, escalating and resetting expectations early as new information emerges.

• A track record of reviewing other engineers’ work and raising quality without slowing teams down.

• Comfort working directly with clients or external stakeholders, you can own a technical conversation, not just support one.

• Experience mentoring engineers more junior than you, formally or informally, on both technical skills and client communication.

• A learning-agile mindset: you can pick up a new framework, platform, or codebase and be productive on it quickly.

• Interest in progressing your career into role leadership, people management, and/or deeper service specialization.

• Background at a consultancy, agency, or in-house CRO / experimentation program at an enterprise brand.

Nice to Have

• Experience running pre-sales / feasibility work and producing client-facing technical deliverables.

• Familiarity with analytics and data layer tooling (e.g., Segment, GTM, GA4) as it intersects with experiment instrumentation.

• A portfolio of reusable patterns, libraries, or internal docs you’ve authored and driven adoption of.

Why Cro Metrics

• Remote-first: Fully remote for employees based in eligible U.S. states.

• Generous time off: 4 weeks of PTO to start, increasing to 5 weeks after 3 years, plus 9 paid holidays and up to 5 days of paid bereavement.

• Health & wellness: Group healthcare coverage, disability and basic life insurance, pre-tax savings accounts, and wellness programs.

• 401(k): Automatic enrollment after 3 months with 100% match up to 4% of salary.

• Leave: Parental and medical leave plans tailored to your situation.

• Connection: Annual company-funded All Hands Trip, active Slack culture (#appreciations, #cro-pet-trics, and more), and a real commitment to feedback and transparency.

• Growth: Individualized Career Plan so your path here is explicit—not implied—plus access to our education reimbursement program after one year of employment.

Compensation: 80,000-110,000.00

Important Note: Cro Metrics is a U.S.-based remote company and is not able to hire in CA, AK, WA, OR, HI, NY, or NJ, or outside of the United States.