Klaviyo & Shopify Retention Developer [Email + SMS + Subscriptions] for Ecommerce Agency (Long-Term)

WHO WE ARE We're Rettain, a retention and growth agency running email & SMS for DTC brands across the US and EU. We live in the technical guts of retention: flows, segmentation, deliverability, integrations, and the data behind it all. Our clients trust us to make their lifecycle marketing run like a machine. THE ROLE We're hiring a senior, deeply technical email & SMS retention engineer. This is the "IT person" of email and SMS marketing: someone who understands not just the strategy, but the wiring underneath it, and who has near-developer skills to back it up. You'll own Klaviyo builds end to end, run SMS through Postscript and Attentive, and handle the Shopify app and integration setup that makes everything talk to each other. We need someone who has already done this inside another email & SMS marketing agency. You know how to juggle multiple brands, hit deadlines, and ship clean work without hand-holding. You're as comfortable inside flow logic, API connections, and data mapping as you are in a campaign calendar, and you can develop (HTML/CSS/Liquid, custom integrations) when the job calls for it. This is a contract-to-hire role. We're starting on contract with the clear intent to move into a long-term, full-time relationship if it's a strong fit. We're looking for someone to grow with us, not a one-off project hire. 🛠 WHAT YOU'LL DO ✅ Build and optimize Klaviyo flows: welcome, abandoned cart/checkout, post-purchase, winback, replenishment, and more ✅ Engineer advanced flow logic: conditional splits, triggers, time delays, and segmentation ✅ Run SMS retention through Postscript and Attentive ✅ Set up, configure, and troubleshoot any Shopify app ✅ Build and maintain integrations between Klaviyo, SMS platforms, subscription apps, and Shopify ✅ Develop custom solutions when needed (HTML/CSS/Liquid, API connections) ✅ Manage subscription retention via Loop Subscriptions and Recharge ✅ Own deliverability, list health, and sender reputation ✅ QA and preview flows before launch to catch issues early 👀 WHO WE'RE LOOKING FOR ✅ Prior experience at another email & SMS marketing agency (NON-NEGOTIABLE) ✅ Developer-level technical skills: APIs, data mapping, HTML/CSS/Liquid, custom integrations (NON-NEGOTIABLE) ✅ Expert-level Klaviyo: flows, conditions, splits, triggers, metrics, and reporting (NON-NEGOTIABLE) ✅ Hands-on experience with SMS, Klavyo Postscript, Attentive (NON-NEGOTIABLE) ✅ Proven work with subscription brands using Loop Subscriptions and/or Recharge (NON-NEGOTIABLE) ✅ Able to set up any Shopify app and build integrations independently (NON-NEGOTIABLE) ✅ Strong grasp of email & SMS deliverability and best practices ✅ Detail-obsessed, systems-minded, and self-directed THE DETAILS ⏱ Hours: Full-time, working European business hours for now 💰 Budget: $1,500 per month 😎 HOW TO APPLY Start your application with the word "FLOWSTATE" so we know you read this fully. Then send us: 1. The email & SMS agency (or agencies) you've worked at, and what you owned there 2. Specific examples of Klaviyo flows you've built (screenshots or live brand examples welcome) 3. A technical integration or custom build you set up, and how you did it