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