Senior Fullstack Engineer (React & Golang)

Fountane Archipelago  ·  Island Role

A Little Bit About the Role

We are looking for a Senior Product Engineer (L3) who thrives in complexity. Most engineers build on blank canvases — you build on someone else’s mess and leave it better than you found it.

The majority of your work at L3 will be on existing, live codebases — disorganised, partially documented, built by multiple teams over multiple years. Your job is to enter those systems, understand them before touching them, extend and clean them without breaking what works, and progressively bring them up to a standard where AI tooling can accelerate further development. This is the core of what L3 does at Fountane. If you have only built greenfield projects, this role will be hard.

You are expected to be genuinely full stack: comfortable owning web applications and mobile apps, the frontend, backend, database, state management, and API integration layer — without needing to hand off to a specialist.

You will work closely with the Concept Engineer on your Island — translating their prototypes into production architecture, raising technical blockers early, and keeping the sprint honest. You will also review code, mentor junior engineers, respond to production incidents, and contribute to the network’s shared knowledge base.

All of this is done primarily with Cursor and Claude as your execution and reasoning tools. AI-assisted engineering is not a feature of this role — it is the method.

AI-First Engineering Expectation

Cursor and Claude are your primary tools — not supplements. Engineers at L3 who are not using AI at the codebase level are not operating at this level.

At L3, AI-assisted engineering means:

• Loading full codebase context into Cursor before writing a single line — understanding the system before touching it.
• Writing scoped, precise refactor prompts that isolate changes to one concern at a time.
• Using Cursor to generate tests that document existing behaviour before any restructuring begins.
• Using Claude for architecture reasoning, decision documentation, and translating CE briefs into structured technical plans.
• Producing inline documentation and decision records as part of the AI-assisted workflow — not as an afterthought.
• Sharing effective prompt patterns and Cursor discoveries with the broader Fountane network — kept to yourself, they are a missed contribution.

Key Responsibilities

Legacy Codebase Refactoring & the Cleaning Phase

This is the primary L3 engagement type at Fountane. You will be handed existing, partially documented codebases — built by previous teams, often without tests, with inconsistent patterns — and your job is to refactor them into a clean, AI-promptable state without losing existing functionality. You use Cursor’s codebase context window to navigate safely, write characterisation tests before touching anything, and make changes in small, reviewable increments. The standard is: every module you leave should be easier to extend by AI tooling than when you found it.

Full Stack Development — Web & Mobile

Build and own the full application layer: React / Next.js web frontends, React Native or Flutter mobile apps, Node.js / Python backends, and relational and non-relational databases. You should be able to pick up web or mobile on any engagement without needing a handoff. Schema design, data modelling, and state architecture are yours to own — including diagnosing and fixing broken or leaking state in existing frontends.

Third-Party API Integrations

Integrate complex third-party services — payments (Stripe), communications (Twilio), auth (Auth0), and others — reliably and without creating brittle dependencies. Own the integration layer end to end: error handling, retries, failure modes, and documentation. If a third-party integration is flaky in production, that is your problem to own.

CE Collaboration & Sprint Integrity

Work directly with the Concept Engineer to translate prototypes into buildable technical plans. Review CE briefs before the sprint starts — if the scope is technically unrealistic, the time to say so is before work begins, not on demo day. Raise blockers against acceptance criteria proactively. You are the technical check on what the CE promises the client.

Security Awareness

Write code that does not require the Lead to security-audit every line. This means: input validation by default, no hardcoded secrets, correct auth scoping, safe handling of user data, and awareness of common vulnerabilities (injection, broken auth, insecure direct object references) in the context of the stacks you work in. You are not the security architect — the Lead owns that — but you are expected to produce code that does not introduce obvious vulnerabilities.

Production Incident Response

When something breaks in production, you are on it. Diagnose the issue, apply a safe fix or rollback, document what happened and why, and hand a clear summary to the Lead for the client post-mortem. Speed matters, but a bad fix that causes a second incident is worse than a slow fix that is correct. Response expectation: acknowledged within 1 hour, resolved or escalated with a clear status within 4 hours.

Codebase Navigation & Safe Refactoring

On all engagements — not just Cleaning Phase work — keep changes small, focused, and reviewable. One type of change per commit. Write tests that document existing behaviour before restructuring. Leave every module easier to understand than when you found it.

Code Review

Review pull requests from L1 and L2 engineers with specific, actionable feedback — not rubber-stamp approvals. A good code review at L3 leaves the author understanding what to do differently next time, not just what to fix now. Review weekly; do not let PRs age.

Mentoring

Review junior engineers’ code weekly with specific, useful feedback — this is distinct from quality-gate code review. The goal here is teaching, not gatekeeping. Run monthly pairing sessions to help them grow. The measure of good mentoring is whether they are becoming more capable and less dependent on you over time.

Documentation

Write short decision records when you make significant technical choices. Leave every module you touch easier to understand than when you found it. Treat documentation as part of the engineering work, not a separate task you do at the end.

Qualifications

• 5+ years of experience as a software engineer, with a strong track record on real production codebases you did not build from scratch — incomplete documentation, inconsistent patterns, other people’s decisions. If your experience is primarily greenfield, this role will be a difficult fit.
• Genuinely full stack across web and mobile: proficient in React / Next.js and at least one of React Native or Flutter, Node.js or Python on the backend, and comfortable with both relational and non-relational databases including schema design.
• Hands-on, daily Cursor and Claude usage at the codebase level. You should be able to describe concretely how you use AI in your engineering workflow — not in general terms.
• Experience integrating complex third-party APIs in production environments — not just following a quickstart guide. You should be able to describe an integration that failed in production and what you did about it.
• Solid security awareness for the stacks you work in: input validation, auth scoping, safe data handling. You do not need a security specialism, but you should not be writing code that introduces obvious vulnerabilities.
• Has conducted meaningful code reviews that improved the code and the author, not just approved the PR.
• Has coached or mentored junior engineers before, and done it well.
• Comfortable with production incident response — diagnosing issues under pressure, applying safe fixes, and communicating clearly to a Lead or client about what happened.
• Treats documentation as part of the job, not an afterthought.
• Bachelor’s or Master’s in Computer Science or a related field, or equivalent experience.

About Fountane

Fountane is a technology ventures lab - one part product studio, one part startup engine. We build high-quality software and AI products for clients ranging from fast-moving startups to large enterprises, and we co-build and invest in new companies when we see the right opportunity.

Founded in 2017 and headquartered in Minneapolis, we have grown to 60+ people across four continents and were recognised as one of America’s fastest-growing companies, ranking No. 699 on the Inc. 5000 with 595% three-year growth.

We are radically open-minded, serious about craft, and direct about expectations. If you want to do meaningful work without politics, this is the place.

Job Summary

We are looking for a passionate and motivated Full Stack Developer with 1–3 years of experience in developing modern web and mobile applications. The ideal candidate should have hands-on experience with React.js, Next.js, Node.js, and React Native, along with a solid understanding of REST APIs, databases, and modern development practices. You will work closely with cross-functional teams to build scalable, high-performance applications.

Key Responsibilities

• Develop responsive web applications using React.js, Next.js, HTML, CSS, Tailwind CSS, and TypeScript/JavaScript.
• Build and maintain backend services using Node.js, Express.js, or NestJS.
• Develop cross-platform mobile applications using React Native and Expo.
• Design, develop, and integrate REST APIs and GraphQL APIs.
• Work with relational and NoSQL databases such as PostgreSQL, MySQL, and MongoDB.
• Implement caching and search solutions using Redis and Meilisearch.
• Collaborate with UI/UX designers, product managers, and QA teams to deliver high-quality software.
• Write clean, reusable, and maintainable code following coding standards and best practices.
• Participate in code reviews, debugging, testing, and performance optimization.
• Use Git/GitHub for version control and collaborate effectively within Agile teams.
• Containerize applications using Docker for consistent development and deployment.

Required Skills

• 1–3 years of experience in Full Stack Development.
• Strong knowledge of JavaScript and TypeScript.
• Hands-on experience with React.js and Next.js.
• Experience in backend development using Node.js, Express.js, or NestJS.
• Knowledge of React Native and Expo for mobile application development.
• Experience working with REST APIs and GraphQL.
• Good understanding of PostgreSQL, MySQL, and MongoDB.
• Familiarity with Redis and Meilisearch is an added advantage.
• Experience with Git, GitHub, and Docker.
• Good understanding of responsive design principles and web performance optimization.
• Familiarity with Linux (Ubuntu) environments is preferred.
• Strong analytical, debugging, and problem-solving skills.
• Excellent communication and teamwork abilities.

Job Description:

We are looking for a skilled and motivated Full Stack Developer with 2–6 years of experience in designing and developing scalable web applications using .NET Core, C#, ReactJS, and MS SQL, with exposure to Microsoft Azure. The ideal candidate should be comfortable working across the full technology stack and demonstrate strong problem-solving abilities in a fast-paced, Agile environment.

Key Responsibilities:

• Design, develop, and maintain robust full stack applications using .NET Core, C#, ReactJS, and MS SQL.
• Build and consume RESTful APIs to support scalable frontend/backend integration.
• Collaborate with product owners, architects, and other developers to deliver high-quality software solutions.
• Participate in code reviews, ensure adherence to best coding practices, and contribute to continuous improvement.
• Write unit and integration tests to maintain code quality and ensure high test coverage.
• Deploy and manage applications in Microsoft Azure and contribute to improving CI/CD pipelines.
• Actively participate in Agile ceremonies such as sprint planning, stand-ups, and retrospectives.
• Troubleshoot and resolve technical issues and performance bottlenecks.

Required Skills:

• 2–6 years of hands-on experience with .NET Core and C# development.
• Proficient in ReactJS and modern front-end technologies (HTML5, CSS3, JavaScript/TypeScript).
• Experience in building and integrating RESTful APIs.
• Solid understanding of object-oriented programming, data structures, and software design principles.
• Experience working with MS SQL Server, including writing complex queries and stored procedures.
• Familiarity with Azure services such as App Services, Azure SQL, Azure Functions, etc.

Preferred Skills:

• Exposure to DevOps practices and tools such as Azure DevOps, Git, and CI/CD pipelines.
• Basic understanding of containerization (e.g., Docker) and orchestration tools like Kubernetes (K8s).
• Prior experience working in Agile/Scrum teams.
• Good communication skills and ability to work collaboratively in a cross-functional team.

Our Core Full Stack

Front-End Engineering 

• React for building complex, state-heavy interactive dashboards 
• JavaScript (ES6+) and TypeScript for type-safe management of simulation data 
• State management (Redux/Zustand) optimized for high-frequency data updates 

Back-End & Microservices 

• .Net and Spring Boot for building high-scale, resilient microservices 
• REST APIs for seamless communication between services and front-end consumers 
• Microservices architecture and system integration patterns 

Engineering Excellence 

• GitHub for version control and rigorous Code Reviews 
• CI/CD pipelines, Docker, and Kubernetes for cloud-native deployment 

Key Responsibilities 

• Low-Level Design (LLD): Convert high-level architectural blueprints into detailed technical designs, including class diagrams, sequence diagrams, and API specifications. 
• Technical Mentoring: Lead and coach the engineering team through pair programming, technical 1-on-1s, and hands-on guidance to elevate overall team competency. 
• Standards Enforcement: Ensure all code adheres to the defined engineering standards, SOLID principles, and design patterns established by the Architects. 
• Code Quality & Review: Conduct comprehensive code reviews to maintain high quality, ensuring the team delivers clean, testable, and maintainable code. 
• Technical Anchoring: Serve as the "go-to" expert for the squad to resolve complex technical blockers and provide clarity on implementation details. 
• Hands-on Development: Direct implementation of critical and complex modules, setting the benchmark for performance and reliability. 
• System Integration: Oversee the technical execution of integrations between full-stack applications and core data layers (Databricks/Neo4j). 
• Delivery Governance: Ensure the squad meets sprint objectives by maintaining a high standard of execution and managing technical debt effectively. 

Preferred Qualifications 

• 8 to 10 years of professional experience in full-stack software development. 
• Proven track record in a Tech Lead capacity, with strong experience in creating Low-Level Designs. 
• Expert-level proficiency in .Net, Spring Boot, and React. 

Strong MERN / Frontend Developer Profile

Mandatory (Experience 1): Must have 2+ years of hands-on experience in software development using MERN stack (MongoDB, Express.js, React.js, Node.js)

Mandatory (Experience 2): Must have 1+ years of frontend development experience with React.js, HTML5, CSS3, JavaScript (ES6+);

Mandatory (Experience 3): Must have experience with Next.js (SSR/SSG, API routes, Server Actions)

Mandatory (Experience 4): Hands-on experience in building RESTful APIs using Node.js and Express.js

Mandatory (Experience 5): Experience writing unit test cases using Mocha, Chai, Jest (or similar), and working in Agile/Scrum environments

Preferred

Preferred (Experience) – Exposure to GCP/AWS/DevOps and cloud-native development

Preferred (Educataion) – B.E /B.Tech /BCA

1. Understanding of python backend development ,with Django ot flask frame work
2.  Design, build and maintain responsive front-end interfaces for applications
3. Collaborate with the rest of the engineering team to design and launch new features
4. Create REST APIs and integrating them with the frontend
5. Test software to ensure responsiveness and efficiency

We have openings for Fullstack / Backend / Frontend Developers who can write reliable, scalable, testable and maintainable code.

At Everest, we innovate at the intersection of design and engineering to produce outstanding products. The work we do is meaningful and challenging - which makes it interesting. Imagine each line of your code, making the world a better place. We work on five workdays weeks, and overtime is a rarity. If clean architecture, TDD, DDD, DevOps, Microservices, Micro-frontends, scalable systems resonate with you, please apply.

To see the quality of our code, you can checkout some of our open source projects: https://github.com/everest-engineering

If you want to know more about our culture:

https://github.com/everest-engineering/manifesto

Some videos that can help:

https://www.youtube.com/watch?v=A7y9RpqXAdA;

https://youtu.be/PPjyP1WPOn8" target="_blank">https://youtu.be/PPjyP1WPOn8

• Passion to own and create amazing product.
• Should be able to clearly understand the customer's problem.
• Should be a collaborative problem solver.
• Should be able a team player.
• Should be open to learn from others and teach others.
• Should be a good problem solver.
• Should be able to take feedback and improve continuously.
• Should commit to inclusion, equity & diversity.
• Should maintain integrity at work

• Familiarity with Agile methodologies and clean code.

• Design and/or contribute to client-side and server-side architecture.

• Well versed with fundamentals of REST.

• Build the front-end of applications through appealing visual design.

• Knowledge of one or more front-end languages and libraries (e.g. HTML / CSS, JavaScript, XML, jQuery, Typescript) JavaScript frameworks (e.g. Angular, React, Redux, Vue.js)

• Knowledge of one or more back-end languages (e.g. C#, Java, Python, Go, Node.js and frameworks like SpringBoot, .NET Core) 

• Well versed with fundamentals of database design.

• Familiarity with databases - RDBMS like MySQL, Postgres & NoSQL like MongoDB, DynamoDB.

• Well versed with one or more cloud platforms like - AWS, Azure, GCP.

• Familiar with Infrastructure as Code - CloudFormation & Terraform & deployment tools like Docker, Kubernetes.

• Familiarity with CI/CD tools like Jenkins, CircleCI, Github Actions..

• Unit testing tools like Junit, Mockito, Chai, Mocha, Jest

Responsibilities

• Hands-On development of the core components of the Product Platform
• Liaison with the Technical Architect and Project Manager to understand project scope and objectives
• Break-up overall project scope into a manageable set of tasks and help the Project Manager define Sprints
• Own the Technical Design for different components of the Product Platform
• Help the Project Manager develop and manage a detailed project schedule and work plan
• Develop the product as per design and structure using appropriate technologies meeting the requirements, quality standards and timelines.
• Technical Mentoring of the Team in an effective and efficient manner to uphold quality
• Provide early insights on a consistent basis to various stakeholders about progress and potential risks
• Escalate issues affecting project delivery to appropriate levels within the company and/or vendor and track them to resolution
• Utilize industry best practices, techniques, and technical standards throughout project execution

Qualifications

• Bachelor's degree in computer science, or a related field or MCA
• 7-10 years of hands-on technical experience with 2-3 years of leading a team
• Strong command over Java, NodeJS, ReactJS, and similar Full Stack technologies
• Strong SQL and NoSQL knowledge for databases like MySQL and MongoDB
• Strong understanding of Git and related strategies like Pull Requests, merging, etc.
• Experience with GoLang preferred
• Exposure to DevOps over at least one Cloud Platforms like AWS or Azure in addition to the experience in developing cloud-native applications
• Strong familiarity with software tools like JIRA, Agile, TDD/BDD methodologies, and best practices
• Strong understanding of Algorithms and Design Patterns with proven ability to solve problems creatively
• Experience seeing projects through the full life cycle
• Strong interpersonal skills and extremely resourceful
• Proven ability to complete projects according to outlined scope, quality, budget, and timeline
• Product development background required