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.

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.

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.

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.

Design, build, and maintain Ruby on Rails APIs and React frontends; architect and optimize PostgreSQL schemas and queries; manage Docker/Kubernetes services and Terraform IaC; implement PKI/mTLS and secure authentication; solve offline data serialization/synchronization; own CI/CD pipelines and support mission-critical field deployments.

Develop and support corporate WordPress sites end-to-end: architecture, backend/server logic, integrations (REST/SOAP), plugin/theme development, deployments, CI/CD, server (nginx/apache) configuration, code reviews, and environment setup.

As a Junior Full Stack Engineer, you'll fix bugs and implement features in a .NET MAUI mobile app and backend, collaborating closely with senior engineers for mentorship and code review.

Design, build, and maintain full-stack web applications using modern JavaScript/TypeScript, Node.js and React. Develop RESTful APIs, scalable back-end services, reusable front-end components, and ETL/microservice integrations. Collaborate with product, UX, QA in Agile teams, write unit tests, optimize performance, and document code and APIs.

You will design, build, and maintain scalable applications using Java and JavaScript, collaborating across teams and managing databases.

Assist in updating the company dashboard by collaborating on UI design and integrating websites, focusing on front-end development with React.

Design, build, and maintain production-grade native mobile SDKs for embedded wallets. Own API design, implementation, testing, releases, documentation, and developer support. Implement secure wallet flows, cryptographic operations, and blockchain interactions while ensuring reliability, observability, and long-term maintainability.

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.

Build and maintain frontend and backend components for a health services platform. Develop responsive UIs, design and integrate REST APIs, optimize performance and security, participate in code reviews, troubleshoot issues, and collaborate in an Agile team to deliver features.

Lead and deliver software solutions, oversee full-stack architecture, mentor engineers, and drive cross-functional initiatives for spacecraft modeling and control platforms.