Top Senior Full-Stack Engineer Jobs in Denver & Boulder, CO

Build scalable, data-intensive products from the ground up, focusing on Java/Kotlin backend services, REST or GraphQL APIs, data access, and React/TypeScript interfaces. Responsibilities include architecture, performance optimization, testing, observability, production troubleshooting, technical documentation, and end-to-end feature ownership. Collaborate with data, reporting, design, and product teams while using AI-assisted development tools to accelerate delivery.

Develop fullstack web applications, enhance platform performance, collaborate on high-impact opportunities, and ensure stable, scalable solutions. Engage in rapid iterations and be a committed team player.

Leads technical vision and strategy for Affirm’s Marketplace, Search, Ads Platform, and consumer experiences. Designs scalable full-stack platforms, guides architecture and technical excellence, coordinates initiatives across engineering teams, mentors engineers, and drives reliable delivery of customer-focused products across iOS, Android, and Web.

Own the specification, design, and implementation of features for FareHarbor’s large-scale web application. Collaborate with product team members, develop scalable and performant full-stack solutions, improve automated testing, resolve technical challenges, and participate in code reviews. The role requires strong Python and JavaScript skills, experience with front-end and back-end frameworks, relational databases, performance optimization, and agile development.

Own end-to-end full-stack feature development across React/TypeScript interfaces and Elixir backend services for spacecraft modeling, simulation, and ground-control software. Drive architecture, technical debt reduction, performance, reliability, testing, API design, and production deployment. Mentor engineers, establish coding standards, collaborate with product, design, QA, operators, and astrodynamics teams, and deliver complex data-dense, real-time applications.

Develop and optimize high-scale Adobe Commerce ecommerce platforms using PHP, JavaScript, Node.js, GraphQL, REST, and MySQL. Separate business logic from presentation layers, improve database and caching performance, build CI/CD validation, monitor production systems with New Relic, and create endurance load tests. Integrate identity, payment, and tax systems while mentoring junior engineers and leading offshore teams.

Lead technical direction and delivery for the Acquisition & Onboarding full‑stack team. Build and maintain mobile (React Native/native) and web experiences, backend services at scale, and operational tooling. Drive architecture, mentor engineers, ensure reliability/monitoring/on‑call readiness, collaborate with product and design, and improve dev processes, testing, and release practices to impact conversion and retention.

Owner of Vannevar's authentication and authorization platform: build tenant-isolated auth systems, self-service user/group/permission admin UI, tooling to visualize and validate access, feature-flag and platform management interfaces, and shared authorization capabilities across products.

Senior fullstack engineer to build and scale Brigit's consumer finance platform. Own end-to-end features across frontend (React/React Native/TypeScript) and backend (Java/REST/SQL), optimize database and APIs for high scale, integrate 3rd-party services, implement risk and transaction algorithms, improve CI/CD, testing, monitoring, and internal tooling to support millions of users.

As a Senior Software Engineer, you will design and build a cutting-edge identity search platform and implement AI systems for defense applications, working closely with cross-functional teams to enhance user workflows and support national security.

Build and own complex frontend features using Vue 3 and TypeScript while developing the Python services and APIs that power them. Improve performance, accessibility, testing, CI/CD, and observability; collaborate with product and design; mentor engineers and apply AI-assisted development tools responsibly to accelerate productivity and maintain quality and security.

Design and implement scalable backend services for payment and transaction workflows using Java. Own end-to-end features from data model and APIs to Angular frontends, improve reliability and performance, refactor legacy systems, troubleshoot production issues, and collaborate with product and design. Leverage AI-assisted development tools responsibly and share best practices across the team.

Responsible for leading a team of engineers, supporting product development, identifying technical issues, and ensuring high-quality code delivery in backend systems at scale.

Lead design and implementation of the PSA Liquidity Platform connecting buyers and sellers. Build buyer tooling, matching/ranking engines, and seller experiences. Architect and operate microservices and Kafka-driven systems on Kubernetes/AWS, instrument observability, apply AI tooling across the SDLC, and drive cross-functional delivery from 0-to-1 while owning end-to-end outcomes.

The Senior Full-Stack Engineer will manage client relationships, design integration solutions, and ensure seamless delivery and optimization of technical workflows, while leveraging AI for efficiency.

Build and ship full-stack features for customer-facing Console and Playground, plus internal tools. Design and maintain APIs and backend services, implement accessible performant frontends, translate product requirements into incremental work, and improve code quality through reviews and design discussions.

Develop and maintain scalable full-stack web applications using Vue 3, Nuxt, Node.js, and TypeScript. Responsibilities include designing user interfaces, building backend services, optimizing performance, managing MS SQL data solutions, debugging, conducting code reviews, and ensuring responsive cross-browser compatibility. The role requires collaboration with distributed teams during Eastern Standard Time and supports remote work. Preferred experience includes Docker, Azure, CI/CD pipelines, and DevOps practices.

Develop and deliver production-ready web experiences for marketing using React, Gatsby, and Tailwind. Build API integrations, maintain a lightweight codebase and design-system components, ensure accessibility, performance, SEO, and multi-region support, participate in code reviews, and help shape tooling and best practices across the team.

Build and launch user-facing, backend-leaning full-stack products for a clinical AI platform. Design reusable accessible frontend components, develop backend features, collaborate with product managers and subject matter experts, protect patient privacy through secure coding, improve engineering practices, and support applications in production.

Design, build, and maintain production-grade .NET web applications and APIs on Azure. Own full-stack delivery from data models and SQL to front-end components, CI/CD, testing, and architecture. Collaborate with product and delivery teams, participate in code reviews, and ensure secure, observable, well-tested services.

Designs and develops full-stack web applications using React, TypeScript, Vue, and UI-focused backend services. Builds REST or GraphQL APIs, BFF architectures, cloud infrastructure, databases, authentication, and caching solutions. Leads performance, accessibility, security, testing, CI/CD, observability, and reliability initiatives. Provides technical leadership through code reviews, architecture decisions, mentoring, refactoring, and cross-team collaboration.

Develop scalable full-stack web applications using React, TypeScript, Next.js or Vite.js, Node.js, and NestJS. Build APIs, integrate databases, third-party services, and blockchain technologies, and create responsive user interfaces. Collaborate with product, design, and engineering teams while optimizing performance, participating in code reviews, testing, troubleshooting, and continuous improvement. The role also involves Web3 wallet and smart contract integrations, technical discussions, and working effectively with distributed teams.

Build and ship end-to-end product features across an author analytics dashboard, marketing site, free tools, billing, email, and AI-assisted functionality. Design data models and APIs, integrate third-party services, develop production LLM features, and maintain testing, monitoring, performance, and observability. The role includes code review, technical documentation, independent product decisions, and close collaboration with the founder in a remote-first environment.

Design, build, and maintain AI-powered B2B SaaS products across frontend, backend, and AI. Own projects end-to-end, collaborate with product and design, ensure maintainability, mentor teammates, and inform roadmap and implementation decisions.

The Senior Fullstack Software Engineer will design, implement, and maintain features for Conveyor's SaaS platform, involving both backend and frontend work, while collaborating closely with team members and mentoring juniors.