Senior Experiment Engineer

Cro Metrics

15h•$80,000 - $110,000•Remote

About The Position

Cro Metrics is a growth optimization agency that partners with mission-driven and high-growth companies to scale through data-driven experimentation. Their expertise spans A/B testing, personalization, and full-funnel digital strategy. The company operates as a fully remote team of strategists, analysts, engineers, and designers across various industries. They emphasize autonomy, collaboration, and innovation in helping clients grow. As a Senior Experiment Engineer, you will be responsible for building and shipping experiments that determine how recognizable brands grow, convert, and retain customers. This role involves developing experiments across a wide range of complexities, including unfamiliar frameworks and platforms. You will work directly with clients to translate business questions into testable hypotheses and build the solutions to validate them. Additionally, you will mentor other engineers through code reviews and provide guidance on best practices, contributing to the overall practice of experimentation as a craft. The ideal candidate is energized by new codebases, enjoys bridging the gap between business problems and technical solutions, and wants their work to have a visible impact on outcomes.

Requirements

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 Haves

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.

Responsibilities

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.
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 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.
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.