Senior Full Stack Web/Mobile Application Engineer
Confirmed on the employer's own hiring board on Oct 28, 2026. First seen by Alion on Sep 5, 2026.
Job title: Senior Full Stack Web/Mobile Application Engineer
Department: Development
The Role:
As our agency grows, we are taking on more and more web and mobile application projects for our clients. Our application frontends are typically built on Next.js and React, with React Native when a project calls for a mobile app. The REST and GraphQL APIs that drive them and integrate with other systems usually run on Node.js or Laravel. You don't need to be an expert in all of these, but we're looking for well-rounded developers who have a working knowledge across these stacks, can learn on their feet, and start contributing quickly to deliver for our clients.
We expect engineers at this level to do their work with AI agents. We use a spec-driven process to plan and specify features with AI before anyone starts implementing them, and our senior engineers help set the AI development standards that the rest of the team follows. We're looking for people who have already built this into how they work and have opinions about what makes it go well.
As a client services agency, we're always expanding into new technologies and platforms to meet our clients needs, so we are looking for developers who love keeping up-to-date on the newest advancements in the field and can figure out when to start applying those advancements to client work.
You'll be working on several projects at any time; typically one or two large application projects and a few smaller projects to keep things fresh.
Key Responsibilities:
- Building new applications, websites, and features with a variety of tools, languages, and technologies, including Next.js, React, React Native, Node.js, and Laravel.
- Planning and implementing work with AI agents, using our spec-driven process to settle the approach before the code gets written, and helping set the AI development standards that more junior engineers follow.
- Acting as the Technical Lead (TL) on your projects. You'll partner with the project manager to lead the project’s development team, and you'll share ownership of the project's financial success alongside its technical success, including managing scope against the budget and raising problems early enough to do something about them.
- Serving as the point of escalation for other engineers on your projects, keeping an eye on architectural decisions and code quality, and guiding more junior developers.
- Contributing to high-level architecture planning and consulting with our internal team on approach and level of effort.
- Flexing your muscles on aspects of application development outside of app code: database modeling, query optimization, setting up efficient logging and monitoring solutions, and other advanced requirements for highly functioning apps (you do not need to be a DBA or devops engineer).
- Staying up-to-date on the latest development technologies and methodologies.
- Communicating directly with clients and our project managers to understand their requirements, work through specifications, make technical decisions, and present status updates and demos.
Skills & Qualifications:
- You should have a minimum of 5 years of professional experience, preferably in a technical role and with agency experience.
- Full Stack experience with a variety of frontend and backend tools and technologies and their surrounding ecosystems is a requirement for this role.
- Experience interacting with and building backend REST and GraphQL APIs
- Knowledge and experience with integrating with third party APIs
- Hands-on experience using AI agents for planning and development in a production codebase, including reviewing what the agent produces before it ships.
- Experience leading a development team or acting as a technical lead, including partnering with a project manager on scope, estimates, and budget.
- Comfort talking directly with clients about requirements, technical trade-offs, and project status.
- Experience building out application user experiences and understanding user behavior and intent, and using this information to build intuitive apps and websites for our clients.
- Knowledge of Git and Github, we use these on all projects.
- Experience with AWS services or other devops platforms is a plus.
The salary range for this position is $95,000 - $140,000 per year, depending on experience
What we offer:
- Healthy work/life balance
- A creative environment to do the best work of your career
- An amazing team of developers, designers, marketers, and project managers.
- Paid Parental Leave
- Paid vacation and sick time off
- Health, Dental, and Vision insurance
- Retirement plan with company matching
About Happy Cog:
Happy Cog is a growing interactive agency of 70+ people, all working 100% remotely.
We design, develop, and market websites and mobile apps for a wide variety of clients -- everyone from small startups, to Fortune 100s. Projects we've recently worked on have included online ordering platforms for restaurants, custom content management systems for law firms, an economic mobility research platform, and many more.
We are looking for great people to join our team, so if you don't check all the boxes, but believe you can do the job, reach out and tell us why!
Happy Cog is an equal opportunity employer and considers applicants for all positions without regard to race, color, religion or belief, sex, age, national origin, citizenship status, marital status, protected veteran status, genetics, sexual orientation, gender identity or expression, physical or mental disability.
We are also proud to have been on the Inc 5000 list of America's fastest growing companies for 7 years in a row! For more information go to our website: https://www.happycog.com
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