Implementation Engineer
LocationRemote (U.S. preferred)
Contract ( with potential to extend into full time)
About the RoleWe’re looking for a Contract Implementation Engineer to support merchant onboarding and technical integrations. This role sits at the intersection of Support Engineering, Product, and Customer Success, and is focused on helping partners successfully implement and launch our APIs and checkout flows.
This is a hands-on, execution-oriented role ideal for someone who enjoys working directly with customers, debugging real-world integration issues, and shipping solutions quickly in a fast-moving startup environment.
What You’ll DoSupport merchants during onboarding and implementation of our Shopify Payment Method solutions
Provide guidance on basic Shopify Marketing Best Practices which include building an HSA/FSA landing page, adding Flex badges to the PDP, and targeted email marketing
Troubleshoot and debug any implementation and post-implementation issues related to both Flex Shopify Payments and Marketing App
Lead post implementation feature enable for Shopify features (e.g. Subscription Support, Passing telehealth consultation costs to customers)
Partner closely with Support Engineering, Product, and Engineering to escalate bugs and unblock launches
Help document common implementation patterns, FAQs, and known issues
Occasionally assist with light data validation or configuration updates in internal tools
2+ years of experience in an implementation, support engineering or customer engineering
Comfortable working with REST APIs, JSON, and HTTP requests
Experience using Postman (or similar tools) to test and debug APIs
Familiarity with webhooks and asynchronous event flows
Strong troubleshooting and problem-solving skills
Clear, empathetic written communication — you’ll be working directly with external partners
Ability to work independently, prioritize tasks, and manage multiple implementations at once
Experience supporting payment systems, subscriptions, or checkout flows
Familiarity with Stripe, Shopify, or other e-commerce platforms
Experience in a startup or high-growth environment
Light SQL or data-debugging experience
Previous experience working with customer-facing technical roles
Independent Contractor (1099) role, fixed-term
Flexible hours, with some overlap with U.S. business hours preferred
Fully remote
Opportunity to extend or convert based on business needs and performance
You’ll play a critical role in getting partners live and successful, while working closely with a small, collaborative team. This role is ideal for someone who likes being close to real customer problems and seeing the direct impact of their work.
Top Skills
What We Do
Flex helps leading health and wellness brands increase AOV by up to 50% and boost checkout conversion by 30% with the only HSA/FSA payments infrastructure purpose-built for eCommerce.









