Middle Full-Stack Developer (Next.js)

ABOUT US Ruby Labs is a leading tech company that creates and operates innovative consumer products. We offer a diverse range of opportunities across the health, education, and entertainment industries. Our innovative teams are driving the future of consumer-led products, and we're always looking for passionate individuals to join us. Learn more about our story at: https://rubylabs.com/about-us/ ABOUT THE ROLE We are looking for a disciplined, highly autonomous Middle Next.js Developer to build and ship product features for one of our core D2C subscription products. You will own features end to end across a TypeScript monorepo — a Next.js App Router client, a Fastify + Payload CMS API on PostgreSQL, and Cloudflare Workers at the edge — from the moment you receive a task, through breaking it down, estimating, implementing, testing, and observability, to a clean release to production and confirmation that it works for real users. This is a hands-on engineering role suited for someone who treats production as the standard, not the finish line. Half-tested code, silent failures, and unverified AI-generated output are not acceptable. The codebase is convention-heavy — a layered Feature-Sliced Design structure with strict import rules — and you are expected to work inside those conventions rather than around them. You are accountable for every task you take on and for every area of the product you touch: if it breaks, regresses, or stays half-finished, that is yours to see through. We expect maximum autonomy and real involvement in the product — you work independently within a sprint, communicate risks before they become blockers, and escalate architectural decisions to senior engineers rather than guessing. KEY RESPONSIBILITIES FEATURE DEVELOPMENT - Build features across the Next.js client and the Fastify + Payload CMS backend according to product requirements - Write code that follows the team's Feature-Sliced Design layering, naming, and import conventions - Ship changes behind feature flags and A/B experiments, fully localized across every supported locale - Integrate third-party providers — billing, email/CRM, analytics — over REST APIs and webhooks QUALITY & RELIABILITY - Cover functionality with unit, integration, and e2e tests at the level the team expects - Run a thorough self-review before code review, and review teammates' code with the same rigour - Fix bugs and perform root-cause analysis for recurring issues - Optimize page and endpoint performance — rendering and caching strategy, database queries, bundle size SECURITY & OBSERVABILITY - Apply secure development practices: schema validation, access control, safe handling of secrets - Follow observability practices — structured logging, metrics, and alerts — using existing tooling COLLABORATION - Break down, estimate, and ship your own tasks to production within the sprint — and stay accountable for them after release - Own the areas of the…