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

Modernize a large fintech platform by building NestJS services and Next.js UIs, migrate transactional data to relational schemas, write comprehensive tests, identify and fix legacy problems, design scalable solutions that coexist with legacy systems, and use AI tooling responsibly to increase engineering velocity.

The Full Stack Engineer will develop features for a dynamic web application, collaborate with team members, enhance performance, and improve automated tests.

As a Fullstack Engineer, you'll design, build, and operate web applications, collaborating with product teams and mentoring peers while ensuring best practices in coding and system architecture.

Build and maintain FareHarbor.me, a managed WordPress site platform. Develop PHP and JavaScript features, craft themes/plugins and Gutenberg blocks, collaborate with design and product, review PRs, write docs, and improve accessibility, performance, and editor UX across thousands of client websites.

Build and own end-to-end full-stack features across backend services and user-facing applications. Contribute to system design, reliability, performance, observability, and engineering practices while collaborating with product and design.

Lead the engineering effort for a seed-stage dating app: audit and improve the existing codebase, design and build v2 (mobile and backend), implement real-time features, define engineering standards, scale infrastructure on AWS, and, after fundraising, hire and mentor a small team while shaping the technical roadmap.

Lead architecture, modernization, and development of Group Insurance applications. Modernize mainframe monoliths into Java microservices and micro-frontends on cloud, mentor distributed Agile teams, collaborate with enterprise architecture, product owners and infrastructure, and enable test automation and integrations. Approximately 10% domestic travel.

The role involves leading application performance improvements across multiple platforms, focusing on measurable metrics and driving engineering standards and workflow optimization, using both hands-on coding and strategic influence.

Build and own Eve's marketing site and GTM engineering stack: integrate and optimize external tools, design AI agents for sales and marketing, implement webhooks and middleware to sync product/CRM data, and create programmatic campaigns and internal tools in partnership with Marketing, Sales, RevOps, and Product to drive growth and automation.

Lead frontend-leaning full-stack implementation work for carrier and enterprise integrations: architect reusable UI and API layers, author RFCs, guide technical delivery, enforce testing and security best practices, and partner with cross-functional teams to scope and ship production integrations.

Develop, maintain and evolve a high-scale US sports trading platform. Build React/TypeScript frontends, backend microservices, optimize SQL and performance, implement CI/CD and automated testing, mentor junior engineers, and collaborate with stakeholders and architecture teams to ensure resilience and integration.

Lead full-stack mission engineer who designs, develops, integrates, and deploys software for DoD/IC missions. Lead cross-functional teams to build high-performance frontends and cohesive systems, collaborate with military customers for product discovery, and deploy and field-test solutions in secure operational environments (travel ~1 week/month).

Design, build, and maintain front-end visualizations and back-end web services for real-time geospatial data. Participate in full software lifecycle, ingest GIS/imagery data, improve tools/processes, and collaborate on modern web frameworks and performance profiling.

As a Senior Software Engineer, you'll design, develop, and maintain full-stack applications, utilizing TypeScript and modern frameworks while collaborating cross-functionally to enhance user experience and performance.

Seeking a full stack engineer to develop applications, requiring skills in Node.js, SQL, and modern JavaScript frameworks with a focus on scalability and performance.

Volunteer Principal Full Stack Engineer to lead and contribute across frontend and backend (React/React Native, Node.js, MongoDB). Own feature development, mentor engineers, collaborate with product/design, ship scalable code, and support CI processes. Must commit 4+ hours weekly and attend a weekly standup; first task includes launching a fundraising campaign.

Design and build a high-performance, AI-native web trading experience for sophisticated retail traders. Ship core trading workflows (order entry, positions, blotter, watchlists, alerts), implement trustworthy AI UI patterns, collaborate with backend engineers on low-latency contracts, and iterate quickly with users and stakeholders to deliver end-to-end product features.

Design, implement, and optimize full-stack solutions. Collaborate with cross-functional teams, participate in code reviews, analyze and improve system performance, and stay current with industry technologies.

Design and implement backend features in Go, build data pipelines and REST APIs, work with PostgreSQL and AWS, contribute to scalable system design, and optionally develop React.js user-facing features while collaborating in a fast-paced AI-focused startup.

The Full Stack Engineer will design, build, and maintain scalable web applications, impact customer onboarding and integrations, write and review code, and support technical improvements.

Design, develop, and deploy full stack web applications. Build front-end and back-end components, integrate systems, write clean documented code, participate in code reviews, troubleshoot issues, and keep current with emerging web technologies and security best practices.

Build and maintain end-to-end product features across frontend, backend, and databases. Design APIs, authentication, data models, integrations, and AI-assisted workflows. Ship production-ready SaaS components, debug across the stack, improve reliability and performance, and collaborate on product and architecture decisions in an early-stage startup.

Design, build, test, and maintain full-stack applications using backend technologies (.NET/NodeJS/Java) and frontend stack (JavaScript/TypeScript/React). Deploy and manage applications on cloud platforms (Azure/AWS/GCP), implement CI/CD pipelines, work in Agile teams, ensure code quality and security, and collaborate across functions to deliver scalable solutions.

Design, build, test, and maintain full-stack web applications using backend frameworks (.NET, NodeJS, Java) and frontend tech (JavaScript/TypeScript, React). Deploy and manage applications on cloud platforms (Azure/AWS/GCP), implement CI/CD pipelines, follow Agile practices, and ensure code quality and security through testing and reviews while collaborating with cross-functional teams.

Develop and implement full stack features for a healthcare platform, focusing on both frontend (React) and backend (Node.js) development. Responsible for performance optimization, API creation, testing, and collaboration with data engineering teams.