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

Lead end-to-end development of full-stack AI features on a Ruby on Rails backend and React frontend. Build and optimize AI infrastructure for production LLM inference, implement RAG and AI agents, design and run experiments and A/B tests, improve tooling and processes for scale, collaborate with designers and leaders, and iterate quickly while maintaining high code quality and user experience.

Lead design and build of an AI-native marketing platform: integrations, multi-agent orchestration, UIs, tooling, analytics, CI/CD, auth/multi-tenancy, and production AI agents to automate marketing workflows and drive adoption across teams.

Owner of end-to-end ecommerce features: design, implement, and maintain scalable backend services and performant React/Next.js frontends. Integrate payment gateways and procurement systems (PunchOut), mentor engineers, uphold code quality, and improve platform stability across Node.js, MySQL, and MongoDB.

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.

Join the Entefy team as a Senior Full Stack Engineer to build a scalable full stack application enhancing digital interaction for global clients.

The Senior Full Stack Developer will build end-to-end solutions, collaborate in a remote environment, and write technical documentation. The role requires expertise in Ruby on Rails and various programming paradigms.

The Senior Fullstack Engineer will build and manage enterprise authentication systems, improve user session management, ensure security compliance, and support internal API usage across services, while enhancing performance and reliability.

As a Senior Fullstack Engineer, you'll contribute to backend development for Toast's New Ventures team, collaborating on architecture and launching MVPs while addressing unmet operator needs.

The Senior Full Stack Engineer will design and implement APIs with NodeJS, develop UIs with React, manage data pipelines, and deploy projects on AWS.

Lead full-stack modernization of DHS ICE legacy systems by analyzing workflows, designing scalable backend services and APIs, and building user-facing React components. Own full SDLC, troubleshoot across application and data layers, collaborate with stakeholders, and translate complex legacy behavior into a modern platform-based architecture.

Build and ship full‑stack growth experiments end-to-end to improve acquisition, activation, engagement, and monetization. Collaborate with product, design, and analytics, analyze experiment results, iterate quickly, and contribute to experimentation platform and growth infrastructure while balancing speed, quality, and long-term maintainability.

Senior full‑stack engineer responsible for building production-quality Salesforce platform capabilities, integrations (MuleSoft, REST/SOAP), AI-enabled tooling (Claude plugins, MCP servers), CI/CD, and reusable libraries. Mentor engineers, run architecture/code reviews, and collaborate cross-functionally to deliver scalable, secure cloud-native solutions using Python, LWC, Apex, and AWS.

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.

The Senior Fullstack Engineer will deliver software products, collaborate with product and business teams, lead technical practices, and ensure high-velocity iteration on a mobile advertising platform.

The Senior Full-Stack Engineer will develop claims monitoring tools and backend services, collaborate with other engineers, and influence the product architecture in a health insurance startup.

As a Senior Full Stack Engineer, you will design and implement features, maintain systems, and ensure performance in a fintech environment, collaborating with cross-functional teams.

Build end-to-end data and analytics features: ingest and model data, build transformations and pipelines, create client-facing dashboards and interfaces, and develop LLM-powered workflows to accelerate analysis and app development. Partner with stakeholders, perform exploratory analyses, and ensure data quality, observability, and maintainability while influencing data engineering strategy.

The Senior Frontend Engineer will enhance Slate's brand management experience by building UI systems, integrating brand assets, ensuring reliability, writing maintainable code, and mentoring junior engineers.

The Senior Backend Engineer will design and build backend systems for real-time collaboration, focusing on performance, reliability, and team workflows while improving existing infrastructure and contributing to architectural decisions.

Lead and contribute to an agile scrum team to deliver scalable web application features within sprints. Complete user stories, troubleshoot issues, design and implement complex software solutions, mentor developers, and maintain system architecture, SDLC adherence, and technical documentation. Must meet DHS EOD and fitness requirements.

Backend-leaning full-stack engineer building Python networking and backend services for USV autonomy. Work includes real-time telemetry, service-to-service communication, simulation integration, C++ interfaces, containerized deployments, orchestration, and operator-facing app support.

Build end-to-end features in a JS/TS stack, designing scalable backend services and responsive real-time frontends. Improve observability, performance, and reliability, collaborate with product/design, and own full-stack implementation from APIs and data models to UI.

As a Senior Full-Stack Engineer, lead development of secure AI-driven SaaS applications, focusing on backend architecture, frontend design, and AI integrations. Collaborate with teams to operationalize models and enhance application functionality through cutting-edge AI solutions.

Build and ship full-stack features for North, develop autonomous agents that access sensitive enterprise data, productionize state-of-the-art models, write minimal, secure low-resource code, and collaborate with researchers to deploy performant RAG/agentic applications while prioritizing security and user experience.

Design and build agent-powered mission consoles, collaborate with stakeholders to improve user workflows, and maintain agentic workflows for mission outcomes.