Back end developer

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.

About Marseer AI

Marseer AI (www.marseerai.com) is a Seattle-based company building an AI-powered marketing intelligence platform for DTC and retail e-commerce brands. The platform combines brand strategy, customer data, automation, and generative AI to help marketing teams drive consistent, data-driven engagement across email, SMS, paid media, SEO, and affiliate channels.

Role Overview

We are looking for an experienced AI Engineer - Full Stack Developer to join the Marseer platform team. This is a dual-track role: you will build and maintain AI agent pipelines, LLM integrations, and RAG-based intelligence systems on the backend, while also owning frontend interfaces that surface insights, recommendations, and campaign outputs to marketing teams and brand operators.

You should be equally comfortable designing multi-step agentic workflows in Python and building clean, responsive product interfaces in React/Next.js. You understand how LLMs behave in production, know how to engineer prompts and tool chains for reliability, and care deeply about the end-to-end user experience.

What You Will Do

- Design and implement multi-step AI agent workflows using LLM orchestration frameworks such as LangChain, LangGraph, CrewAI, or similar.

- Build and maintain RAG pipelines, including chunking strategies, embedding generation, vector store management, and retrieval tuning.

- Integrate with LLM providers such as OpenAI, Anthropic, or others, including prompt engineering, tool/function calling, structured output generation, and context window management.

- Develop AI-driven features such as campaign brief generation, audience recommendations, content variant creation, and performance insight summarization.

- Implement evaluation and observability frameworks to monitor LLM output quality, latency, and cost in production.

- Build frontend interfaces using React and Next.js, including dashboards, agent interaction UIs, campaign builders, and insight surfaces.

- Design and implement RESTful and/or GraphQL APIs in Python (FastAPI or Flask) or Node.js to serve AI outputs to the frontend.

- Integrate frontend with backend AI services, streaming LLM responses, and real-time status updates.

- Work with structured and unstructured marketing data, campaign performance metrics, audience segments, content libraries, and brand strategy documents.

- Integrate with marketing platforms and data sources such as Klaviyo, Google Ads, Meta, and Shopify.

Requirements

- 5-10 years of professional software engineering experience, with meaningful time in both backend and frontend development.

- Proven experience building and deploying LLM-powered applications in production, not just prototypes.

- Strong proficiency in Python for backend and AI development.

- Strong proficiency in React and Next.js for frontend development.

- Hands-on experience with LLM orchestration frameworks such as LangChain, LangGraph, CrewAI, or equivalent.

- Experience building RAG pipelines, vector stores such as Pinecone, Weaviate, pgvector, or similar, embedding models, and retrieval strategies.

- Experience with API design, REST or GraphQL, and backend service architecture.

Strongly Preferred

- Experience designing and building multi-agent or agentic AI systems with tool use, memory, and planning capabilities.

- Familiarity with prompt engineering best practices, structured output generation, and LLM evaluation methodologies.

- Experience with streaming LLM responses and real-time UI updates using SSE or WebSockets.

- Prior work in a SaaS product company shipping production features.

- Familiarity with marketing platforms, e-commerce data, or martech ecosystems.

Good to Have

- TypeScript and modern frontend tooling such as Tailwind CSS or shadcn/ui.

- Familiarity with Snowflake or other cloud data warehouses as data sources for AI pipelines.

- Experience with observability tools for LLM applications such as LangSmith, Helicone, Arize, or similar.

- Understanding of marketing concepts such as segmentation, campaign lifecycle, attribution, and content personalization.

What We Are Looking For

- Availability to work US business hours; overlap with US Eastern or Pacific timezone is required for client collaboration and team standups.

- Strong written and verbal English communication.

- Product sense and ownership mindset.

- Comfort with ambiguity in non-deterministic LLM-powered systems.

- Collaborative working style across engineering, design, and client-facing functions.

What We Offer

- Competitive compensation based on experience.

- Fully remote role; work from anywhere in India, with Hyderabad-based candidates preferred.

- High-impact work at the frontier of applied AI for marketing and e-commerce.

- Direct exposure to real brand problems, real data, and real production AI systems.

- A small, senior team where your architecture decisions matter and your contributions are visible.

We are looking for a Node.js Lead Developer responsible for managing the interchange of data between the server and the users. Your primary focus will be the development of all server-side logic, definition and maintenance of the central database, and ensuring high performance and responsiveness to requests from the front end. You will also be responsible for integrating the front-end elements built by your co-workers into the application. Therefore, a basic understanding of front-end technologies is necessary as well.

As a MERN Stack Developer / Software Architect, you will play a crucial role in the architecture, development, and leadership of our digital products. You will collaborate closely with cross-functional teams to create exceptional user experiences, while also ensuring the scalability, security, and performance of our applications.

Responsibilities:

• Architecture and Technical Leadership: Design and develop the architectural roadmap for the website and mobile app. Lead and mentor a team of 8-9 MERN Stack developers, providing technical guidance, code reviews, and best practices to ensure high-quality solutions.
• Full Stack Development: Hands-on contribution to the development of complex features and functionalities using the MERN (MongoDB, Express.js, React, Node.js ) stack. Implement robust and maintainable code that aligns with industry standards.
• Scalability and Performance: Collaborate with the team to optimize application performance, ensuring that the platform can handle increased traffic and usage while maintaining a seamless user experience.
• Code Quality and Best Practices: Enforce coding standards, conduct regular code reviews, and implement best practices for software development. Ensure that the team follows coding, testing, and documentation standards consistently.
• Technical Evaluation: Evaluate and adopt new technologies, tools, and frameworks that can enhance the development process and overall product quality.
• Collaboration: Work closely with Product Managers, Designers, and other stakeholders to translate business requirements into technical solutions. Collaborate effectively with cross-functional teams to deliver on time and within scope.
• Problem Solving: Troubleshoot complex technical issues and provide innovative solutions to challenges that may arise during the development lifecycle.
• Continuous Learning: Stay updated with the latest trends, technologies, and best practices in the MERN stack and software architecture domain. Share knowledge and promote a culture of learning within the team.

Requirements:

• Bachelor's degree in Computer Science, Engineering, or related field. Master's degree is a plus.
• 7-10 years of professional experience in software development, with a strong focus on MERN stack development.
• Proven experience in designing and implementing scalable, high-performance web applications and mobile apps.
• Solid understanding of software architecture principles and design patterns.
• Previous experience in a leadership or technical mentorship role.
• Strong proficiency in MongoDB, Express.js, React, and Node.js .
• Experience with cloud platforms (e. g., AWS, Azure) and DevOps practices.
• Excellent problem-solving skills and a proactive attitude towards addressing challenges.
• Effective communication and collaboration skills.
• Prior experience in the health and wellness industry is a plus.

1. Responsibilities 

   • • Collaborate with the core team building a state-of-the-art blockchain based SaaS. 
   • • Building front-end web applications using latest technologies. 
   • • Suggest and ideate high- and low-level design and architecture requirements for implementation of features. 
   • • Apply comprehensive knowledge and a thorough understanding of concepts, principles, and technical capabilities to perform varied tasks and projects. 
   • • Backend RESTful API Design and server-side development for web and mobile apps. 
   • • Develop and design database schemas on MongoDB. 
   • • Perform code reviews and unit tests to ensure code consistency and maintainability. 
   • • Setup alerts, monitoring & metrics, provision and manage resources on AWS Cloud. 

    

   Minimum Qualifications 

   • • Passion to solve complex problems of agriculture in a dynamic start-up environment 
   • • Flexible, curious, exploratory, and can-do attitude 
   • • Great sense of ownership and ability to work with very limited supervision 
   • • Bachelor's degree in Computer Science, related technical field, or equivalent practical experience. 
   • • 2-5 years of hands-on coding expertise in software engineering. 
   • • Experience with JavaScript, HTML, CSS. 
   • • Ability to speak English fluently. 

    

   Preferred Qualifications 

   • • Strong programming experience of 2+ years with Node.js, Express.js, MongoDB and Angular stack. 
   • • Strong problem solving/troubleshooting skills. 
   • • Experience with software design and architecture for building highly efficient and scalable systems. 
   • • Experience with MongoDB Atlas for database hosting and storage. 
   • • Experience with SDLC in an Agile work environment using tools like Jira and GitHub. 
   • • Experience with AWS Services like ECS, EKS, EC2, S3, Lambda, Load Balancing, Route 53, API Gateway along with Infrastructure provisioning and optimization. 
   • • Knowledge and experience of NoSQL Databases is a must. 
   • • Experience with DevOps, CI/CD pipelines on Jenkins, GitHub Actions, etc. 
   • • Experience with containerization environments like Docker & Kubernetes. 
   • • Experience with Material Design is an advantage. 
   • • Experience with TDD is an advantage. 
   • • Experience or familiarity of blockchain protocols like Hyperledger Fabric a big advantage. 

• Experience in building reusable, and modular UI components and ensure cross browser compatibility.
• 3+ years developing, deploying, and supporting web applications built on framework. like Django/ NodeJS/ ReactJS.
• Must have 3+ years of current experience in Python or Go
• Knowledge in writing automated tests
• Proficient in High Level Systems Integration Design
• Understanding of Accessibility and internationalization
• Proficient in source control using GitHub
• Experience with building and maintaining a SaaS product at scale
• Write code that is tested and testable and you take responsibility for the quality of the code you produce. You will be helping build the best user experience for our Anaplan platform.
• Work in a hybrid cloud infrastructure, considering the implementation of functionality through several distributed components and services.
• Express your positive energy and enthusiasm - cultural fit is a really big deal for us. we're looking for really committed people who love solving big problems and are self-motivated to get things done.
• Familiar with developing SaaS applications using Django, NodeJS, ReactJS for development, be an added plus.

As a Software Architect a Typical Day Might Include the Following:

• Work with product/tech team to discuss/define the architecture or solution of a given problem statement
• Set the end-to-end technical direction for the team, including platform, technology, tools, and infrastructure
• Communicate architecture in an effective and professional manner
• Drive technical decisions, solve tough problems, and coordinate multiple project execution
• Ensure that the inContact Development coding quality standards and review processes are followed to ensure proper security and high availability standards
• Monitoring the quality of code that is delivered through reviews and other processes
• Foster strong teamwork environment and create passion and energy within the team
• Be an active participant in the development leadership team ensuring corporate success

To Land This Gig You'll Need:

• BE/B.Tech in Computer Science, or equivalent work experience
• 7+ years of software development experience
• Experience with developing large enterprise-scale application in AWS
• Full-stack experience with PHP, MySql, ReactJS, SQL/NoSQL and readiness to work with teams using other technology stacks like Java, Golang
• Strong quality orientation
• Expertise in designing application using relational and/or non-relational databases
• Working Knowledge of CI/CD
• Experience with micro-service design
• Experience architecting systems for performance and scalability
• Experience in product development
• Excellent problem-solving abilities
• Excellent decision-making skills
• Working Knowledge of design patterns
• Working Knowledge of Agile development processes
• Strong communication skills

Responsibilities 

Design, implementation and delivery of solutions.

Solving new problems and address any issues regarding the architecture and performance. 

Focused on understanding customer needs and anticipate the changing business and technology landscape. 

Collaborate with teams from various verticals within and outside the company.

Qualifications 

2-5 years of Software Engineering experience in Node.js and React. 

Proven experience in architecting performant, complex application on web or mobile applications. 

Knowledge of end to end Software development life cycle.

Ability to work individually or in teams and mentor new developers to the team.

Strong knowledge of computer science, algorithms and design patterns. 

A degree in Computer Science or related field, or equivalent industry experience.