Senior Full Stack Engineer

Description 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 turn those insights into polished, user-facing improvements.

Our primary application stack is Ruby on Rails and Next.js. We’re open to engineers with strong full-stack experience in Rails or closely related backend frameworks such as Django/Python, Laravel/PHP, or Phoenix/Elixir. We’re looking for engineers with deep React and Next.js experience and a strong track record of owning customer-facing product work across the full stack.

You will:

Build and ship full-stack product features across Ruby on Rails and Next.jsOwn product initiatives end-to-end, from identifying opportunities and shaping solutions through implementation, launch, measurement, and iteration

Build user-facing features and experiences that make our products more useful, intuitive, and enjoyable

Partner closely with product/project managers and designers to understand customer pain points, evaluate opportunities, and determine what should be built

Use Claude Code and Codex as a core part of your development workflow to explore codebases, develop solutions, test ideas, and ship efficiently

Make practical technical decisions that balance speed, quality, maintainability, performance, and customer impact

Work across the frontend and backend as needed, rather than being limited to one layer of the stack

Use tools like Datadog and Mixpanel to understand production behavior, investigate issues, measure impact, 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

Highly experienced with React and Next.js and comfortable owning customer-facing experiences from frontend through backend

Experienced with Ruby on Rails or a closely related product-focused backend framework such as Django/Python, Laravel/PHP, or Phoenix/Elixir Fluent with AI-assisted development tools such as Claude Code or Codex and already use them meaningfully as part of your software development workflow

Proven at building, launching, and improving large-scale customer-facing web applications

Able to point to meaningful user-facing or visual product improvements you’ve helped shape and ship, not just improvements to the underlying code or architecture

Product-minded, with strong instincts for customer needs, UX quality, business value, and technical tradeoffsA self-starter who brings structure to loosely defined problems and drives them through execution

Comfortable working in a modern production environment that includes Type Script, MySQL/Postgres, Redis, MongoDB, Sidekiq, Open Search, AWS, Docker, and related infrastructureA strong partner to Dev Ops, with enough understanding of system architecture, cloud infrastructure, deployment, containerization, and infrastructure-as-code 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

Benefits

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…