Senior Full Stack Engineer

Sincere is looking for a Senior Full Stack Engineer to help us make our products meaningfully better. This is a high-ownership individual contributor role for a seasoned engineer who can take a broad product area, understand the customer and business needs, and ship high-quality improvements. You will: Build full-stack features across Ruby on Rails and Next.js Own product initiatives end-to-end, from identifying opportunities and shaping solutions through implementation, launch, and iteration. Partner with product/project managers and designers to identify customer pain points, uncover product opportunities, and deliver meaningful improvements. Use tools like Claude Code and Codex as a core part of your workflow to explore, develop, test, and ship Make practical technical decisions that balance speed, quality, maintainability, performance, and customer impact Build polished, reliable, easy-to-use experiences with strong attention to UX Use tools like Datadog and Mixpanel to monitor production behavior, investigate issues, and inform product decisions Champion new ideas and continuously look for ways to improve our products, engineering practices, and customer experience. You are: A seasoned full-stack engineer with 7+ years of professional software development experience Comfortable working across our stack, including Ruby on Rails, TypeScript, React, Next.js, MySQL/Postgres, Redis, MongoDB, Sidekiq, OpenSearch, AWS, and Docker Fluent with AI-assisted development tools such as Claude Code or Codex Proven at building and maintaining large-scale customer-facing web applications Product-minded, with strong instincts for customer needs, UX quality, business value, and technical tradeoffs A self-starter who brings structure to loosely defined problems and drives them through execution A strong partner to DevOps, with enough understanding of system architecture, cloud infrastructure (AWS), deployment, containerization, and infrastructure-as-code (Terraform) to collaborate effectively Skilled at working in mature codebases, understanding existing architecture, and improving systems pragmatically Detail-oriented, with high standards for both the code and the customer experience Entrepreneurial, curious, and biased toward building, experimenting, and shipping Collaborative and low-ego, with strong communication skills and pride in your craft Do you want to work at a growing company that invests in its team more than the average employer? Sincere is a family of brands with heart. The Company is home to Punchbowl®, Lovebird®, Timehop®, and Memento®, and builds technology that brings you closer and helps show you care to the people who matter the most. With Sincere Foundation, we support organizations that address basic needs, and envision a future where everyone has the opportunity to celebrate, recognize milestones, and honor memories. We provide a fun, casual, and innovative environment where hard work is recognized and rewarded. What We Offer: 100% Health, Dental & Vision coverage 401K Plan with Profit Share Annual bonus potential Health & Wellness stipends Paid time off plus 12 paid holidays & Summer Fridays Paid parental leave Childcare benefits (dependent care FSA) Flexible, hybrid work environment In-person, all-expenses-paid Team Summits (2X a year) PLEASE NOTE: Our team is primarily based in Greater Boston. We will consider applicants who reside anywhere within a 2 hour drive of the city. While this role is remote, we have occasional in-person meetings at the office (every 4-6 weeks typically). The base salary range for this role is $110,000 - $130,000. Actual salary may vary based on skills and experience.