Full Stack Developer, Senior

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.

Profile: MERN Stack Developer

📍 Location: Andheri East, Mumbai

🏤 Work Mode: 5 Days WFO

⏰ Experience: 2+ Years

(Only immediate joiners & candidates who have completed notice period)

What We're Looking For:

✅ 2+ years of MERN stack development experience

✅ MongoDB - database design and complex queries

✅ Express.js - server-side application development

✅ React.js - component-based UI development

✅ Node.js - backend JavaScript runtime

✅ Kafka - event streaming and messaging

✅ Docker - containerization and deployment

✅ Redis - caching and session management

✅ RESTful API design and integration

Key Responsibilities

• Design, develop, and maintain full-stack web applications using MongoDB, Express.js, React.js, and Node.js
• Build and optimise RESTful APIs and micro services
• Work closely with product managers, designers, and developers to deliver scalable solutions
• Write clean, maintainable, and testable code
• Ensure application performance, security, and responsiveness
• Mentor junior developers and contribute to code reviews

🔹 Must-Have Skills

• Strong hands-on experience with MERN stack (MongoDB, Express, React, Node.js)
• Proficiency in JavaScript (ES6+), HTML5, CSS3
• Experience with Redux / State Management in React
• Solid backend expertise with Node.js & Express.js
• Database design, queries, and performance tuning in MongoDB
• Good understanding of REST APIs, authentication (JWT, OAuth)
• Familiarity with Git, CI/CD pipelines, and Agile methodology
• Exposure to cloud platforms (AWS, Azure, GCP) is a plus

🎯 Preferred Skills

• Experience with TypeScript
• Knowledge of GraphQL, Docker, Kubernetes
• Unit testing with Jest / Mocha
• Experience mentoring or leading small teams

🎓 Education

• Bachelor's / Master's in Computer Science, IT, or related field

Founding Engineer - LITMAS

About LITMAS

LITMAS is revolutionizing litigation with the first AI-powered platform built specifically for elite litigators. We're transforming how attorneys research, strategize, draft, and win cases by combining comprehensive case repositories with cutting-edge AI validation and workflow automation. We are a team incubated by experienced litigators, building the future of legal technology.

The Opportunity

We're seeking a Founding Engineer to join our core team and shape the technical foundation of LITMAS. This is a rare opportunity to build a category-defining product from the ground up, working directly with the founders to create technology that will transform the US litigation market.

As a founding engineer, you'll have significant ownership over our technical architecture, product decisions, and company culture. Your code will directly impact how thousands of attorneys practice law.

What You'll Do

• Architect and build core platform features using Python, Node.js, Next.js, React, and MongoDB
• Design and implement production-grade LLM systems with advanced tool usage, RAG pipelines, and agent architectures
• Build AI workflows that combine multiple tools for legal research, validation, and document analysis
• Create scalable RAG infrastructure to handle thousands of legal documents with high accuracy
• Implement AI tool chains to provide agents tool inputs
• Design intuitive interfaces that make complex legal workflows simple and powerful
• Own end-to-end features from conception through deployment and iteration
• Establish engineering best practices for AI systems including evaluation, monitoring, and safety
• Collaborate directly with founders on product strategy and technical roadmap

The Ideal Candidate

You're not just an AI engineer, you're someone who understands how to build reliable, production-grade AI systems that users can trust. You've wrestled with RAG accuracy, tool reliability, and LLM hallucinations in production. You know the difference between a demo and a system that handles real-world complexity. You're excited about applying AI to transform how legal professional’s work.

What We're Looking For

Must-Haves

• Deployed production-grade LLM applications with demonstrable experience in:
• Tool usage and function calling
• RAG (Retrieval-Augmented Generation) implementation at scale
• Agent architectures and multi-step reasoning
• Prompt engineering and optimization
• Knowledge of multiple LLM providers (OpenAI, Anthropic, Cohere, open-source models)
• Background in building AI evaluation and monitoring systems
• Experience with document processing and OCR technologies
• 3+ years of production experience with Node.js, Python, Next.js, and React
• Strong MongoDB expertise including schema design and optimization
• Experience with vector databases (Pinecone, Weaviate, Qdrant, or similar)
• Full-stack mindset with ability to own features from database to UI
• Track record of shipping complex web applications at scale
• Deep understanding of LLM limitations, hallucination prevention, and validation techniques

Tech Stack

• Backend: Node.js, Express, MongoDB
• Frontend: Next.js, React, TypeScript, Modern CSS
• AI/ML: LangChain/LlamaIndex, OpenAI/Anthropic APIs, vector databases, custom AI tools
• Additional: Document processing, search infrastructure, real-time collaboration

What We Offer

• Significant equity stake true ownership in the company you're building
• Competitive compensation commensurate with experience
• Direct impact your decisions shape the product and company
• Learning opportunity work with cutting-edge AI and legal technology
• Flexible work remote-first with a global team
• AI resources access to latest models and compute resources

Interview Process

One more thing: Our process includes deep technical interviews and fit conversations. As part of the evaluation, there will be an extensive take-home test that should expect to take at least 4-5 hours depending on your skill level. This allows us to see how you approach real problems similar to what you'll encounter at LITMAS.

• Efficiently realize the UI/UX needs and deliver excellent front-end features.
  
• Maintain quality of our SAAS platform and ensure responsiveness of applications/cloud-run services.
  
• Collaborate with the rest of the teams to design and launch additional/new features and services.
  
• Develop and maintain the source codes.
  
• Optimize and stabilize the overall service architecture (front) from both engineering and commercial point of view.

• Should be highly skilled in the MERN (MongoDB, Express, React, Node)stack.
  
• Should have knowledge of different React Hooks, and should be able to develop custom hooks.
  
• Should have an understanding of making good-looking plots, an understanding of D3.js is preferred.

Job Description:

We are looking for a highly capable Node.js developerto optimize our web-based application performance. Collaborating with our front-end application developers, designing back-end components, and integrating data storage and protection solutions.

Full Stack Responsibilities:  Developing and maintaining allserver-side network components.  Ensuring optimal performance of the central database and responsivenessto front-end requests.  Collaborating with front-end developers on the integration of elements.  Designing customer-facing UI and back-end servicesfor various business processes.  Developing high-performance applications by writing testable,reusable, and efficient code.  Implementing effective security protocols, data protection measures, and storage solutions.  Running diagnostic tests,repairing defects, and providing technicalsupport.  Documenting Node.js processes, including database schemas, as well as preparing reports.  Recommending and implementing improvementsto processes and technologies.  Keeping informed of advancementsin the field of Node.js development.

Requirements:  Bachelor's degree in computerscience, information science, orsimilar.  At least two years of experience as aNode.js developer.  Extensive knowledge of JavaScript, web stacks, libraries, and frameworks.  Knowledge of front-end technologiessuch as HTML5 and CSS3, Angular, Reactjs.  Superb interpersonal, communication, and collaboration skills.  Exceptional analytical and problem-solving aptitude.  Availability to resolve urgent web application issues outside of business hours

Experience: 2 to 5 years

Annual CTC: Rupees 6,00,000 to 10,00,000

TechUnity is looking for a highly motivated and skilled React JS / React Native software developer who is comfortable with both front and back-end programming. Developer will be designing and implementing attractive and intuitive Web-based user interface and developing backend services to support front-end requests. Developer will be required to see out a project from conception to final product, requiring good organizational skills and attention to detail.

Other Responsibilities:

· Seeing through a project from conception to finished product

· Designing and coding of frontend web architecture

· Designing user interactions on web pages

· Developing backend server architecture

· Creating specification for servers and databases needed

· Ensuring responsive performance of applications.

· Designing and developing APIs.

· Meeting both technical and consumer needs.

· Staying abreast of developments in web applications and programming languages

· Good problem-solving skills.

· Excellent verbal communication skills

Skills Required

• 8+ years of industry work experience
• Proven experience as a Full Stack Developer or similar role
• 3+ years of web application development with JavaScript as full stack
• Full stack experience designing and building scalable applications from end-to-end 
• Excellent JavaScript / Typescript skills
• Strong proficiency in React (hooks knowledge is plus)
• Strong proficiency in Nodejs
• Good HTML5 / CSS3 skills with expertise on responsive web design 
• Must have Design and development experience in Micro services using NodeJS and TypeScript
• Experience with NoSQL databases such as MongoDB, mongoose, aggregation framework and Redis 
• Experience with Web sockets and related frameworks (e.g. Socket.IO) 
• Experience in using and developing GraphQL APIs
• Experience in performance tuning
• Knowledge of code versioning tools such as Git, Mercurial or SVN.
• Open minded to take up any challenge, research and provide solutions 
• Great attention to detail
• Testing libraries – jest, testing-library is plus
• TDD / BDD experience is plus
• Experience with AWS, K8S, CI/CD is plus
• Familiar with SDLC methodologies like SCRUM, AGILE, Continuous Integration

• Design – Analyze, design & document the system / solution based on the business needs which is scalable, resilient and maintainable with low overhead for both client and server side
• Problem solving – Solve the challenges and problems faced by team by guiding and team with best practices
• Coordinate - Communicate system requirements to developers; explain system structure to them and provide assistance
• Code Reviews – Perform code reviews 
• Planning – Plan and assign tasks to team members
• Develop – Develop micro services and micro frontends

Work Environment Details:

Founded in 2011 and trusted by companies across 70 countries and more, KnowledgeHut is the skills solutions provider that organizations and individuals the world over count on to innovate faster and create progress.
We help technologists master their craft and take control of their careers. We empower businesses everywhere to build adaptable teams, speed up release cycles and become scalable, reliable, and secure.  
Our mission to democratize technology skills is what drives us, and our values are at the helm of how we work together. We thrive in an environment with creativity around every corner, challenges that keep us on our toes, and peers who inspire us to be the best we can be.  
If you have the development skills required and are excited to come to work every day knowing you’re helping our customers build the skills that power innovation, we want to hear from you!

Job description:

Red Ant Media helps its clients in building digital creative solutions to help them achieve their business goals. As an outsourced product development company, we embrace the crossroads of Creative design, Web development, Web design, and Digital Marketing.

We are a data-driven agency, who bring together data-driven insights, user objective, brand, technology, content, and creative vision.

Experience: 1 -2 years

Location: Chennai

Roles and Responsibilities:

• Integration of user-facing elements developed by front-end developers with server-side logic
• Writing reusable, testable, and efficient code
• Design and implementation of low-latency, high-availability, and performant applications
• Implementation of security and data protection
• Integration of data storage solutions ( MySQL, MongoDB)
• Creating database schemas that represent and support business processes.
• Understanding the nature of asynchronous programming and its quirks and workarounds

Skills Required:

• Knowledge of Node.js and framework available for it (such as express).
• Familiarity with Progressive Web Applications and Single Page Applications and frameworks (Vue, React, Angular with Typescript, etc).
• Hand on and implement complex Angular applications, directives, pipes, interceptors, services, etc.
• Node-based module loaders and task runners (Webpack, Gulp, or Grunt), creating npm modules.
• Proficient understating of code versioning tools, such as GIT.
• Basic understanding of front-end technologies, such as HTML5, SCSS, and CSS3.