LIMRS Construction & Interior – Backend Developer (NodeJS, NestJS, AI & Cloud Integrations)
Posted: Mon Dec 01, 2025 2:49 am
Preparation Guide for the Backend Developer (Node.js / NestJS) Position
1. Understand the Job Context
• The role focuses on building, optimizing and scaling cloud‑based backend services.
• Core technologies: Node.js, NestJS, TypeScript, Express.js.
• Key integrations: OpenAI / LangChain (or similar AI tools), n8n (or Zapier/Airflow), Firebase, Firestore, Google Cloud Functions, Google APIs, Docker, CI/CD pipelines.
• Databases: MongoDB and PostgreSQL – both the data model and performance tuning are critical.
• Deployment platforms: DigitalOcean and Google Cloud (Firebase).
2. Technical Skill Deep‑Dive
a. Node.js / NestJS / TypeScript
– Review the NestJS architecture (modules, providers, controllers, interceptors, guards).
– Practice building RESTful APIs and GraphQL resolvers in NestJS.
– Master TypeScript features (generics, utility types, decorators).
– Implement middleware, custom pipes and exception filters for robust error handling.
b. Express.js (for legacy code or micro‑services)
– Refresh routing, middleware chaining, error handling, and request/response lifecycle.
c. Databases
– MongoDB: schema‑design with Mongoose, aggregation pipelines, indexing strategies, sharding basics.
– PostgreSQL: relational modeling, advanced SQL (CTE, window functions), query optimisation, partitioning.
– Practice migrations (typeORM or Prisma) and transaction handling in both databases.
d. AI Integration (OpenAI, LangChain)
– Sign up for OpenAI API, explore completions, embeddings, assistants, function calling.
– Build a small prototype that calls the API from a NestJS service, handles rate limits, and caches results.
– Review LangChain concepts: chains, agents, memory, retrievers. Create a simple chain that queries a vector store built on PostgreSQL.
e. Workflow Automation (n8n)
– Install n8n locally or use the cloud version.
– Design a workflow that pulls data from a PostgreSQL table, processes it via a custom Node.js function, and writes the result back to Firestore.
– Familiarize yourself with webhooks, triggers, and the n8n API for programmatic workflow creation.
f. Firebase / Firestore / Google Cloud Functions
– Set up a Firebase project, enable Firestore in native mode, write security rules.
– Deploy a simple Cloud Function (HTTP trigger) that writes data to Firestore.
– Explore background triggers (onCreate, onUpdate) and integrate them with NestJS services via REST or gRPC.
g. Google APIs (Drive, Maps, Sheets, etc.)
– Create a Google Cloud Service Account, enable needed APIs, generate OAuth credentials.
– Write a NestJS service that authenticates with Google and reads/writes a Google Sheet.
– Experiment with the Maps Geocoding API for address validation in a sample endpoint.
h. Containerisation and CI/CD
– Write a Dockerfile for a NestJS app (multi‑stage build, non‑root user).
– Compose a docker‑compose.yml that brings up MongoDB, PostgreSQL and the NestJS container.
– Set up a simple GitHub Actions workflow: lint → test → build → push Docker image → deploy to DigitalOcean (App Platform) or Firebase Hosting (via firebase-tools).
i. Version Control & Collaboration
– Practice rebasing, squashing commits, and pull‑request workflow.
– Configure branch protection rules, code‑owners and automated code‑review bots.
3. Build a Relevant Portfolio
• Create at least two public GitHub repositories:
1. A full‑stack mini‑project using NestJS, PostgreSQL, and a GraphQL API, with Dockerised deployment to DigitalOcean.
2. An AI‑augmented service that integrates OpenAI (or LangChain) with n8n for automated content generation, persisting results in Firestore.
• Document each project with a concise README, architecture diagram, API specs (OpenAPI), and a short video demo.
• Write a technical blog post (Medium, Dev.to) describing a challenging integration you solved—e.g., “Caching OpenAI embeddings in PostgreSQL for real‑time recommendation”.
4. Certifications and Courses (optional but advantageous)
– Node.js Certified Developer (OpenJS)
– NestJS Advanced Training (Udemy or official NestJS workshops)
– Google Cloud Associate Engineer (covers Cloud Functions, IAM, APIs)
– MongoDB University – Performance & Indexing course
– OpenAI API Quickstart (official documentation)
5. Interview Preparation
a. Coding Rounds
– Solve problems on platforms that emphasize TypeScript (LeetCode, HackerRank, Codeforces).
– Practice data‑structure questions that involve real‑world scenarios, such as “Design a rate‑limited API gateway” or “Implement a pagination system for a large MongoDB collection”.
b. System Design
– Prepare for designing a scalable backend for an AI‑driven chatbot: discuss API gateway, authentication (JWT/OAuth), async processing (queues, n8n), data storage choices (PostgreSQL for structured data, MongoDB for logs), cache layer (Redis), and deployment (Docker on DigitalOcean).
– Review CAP theorem, eventual consistency, and techniques to handle AI latency (circuit breaker, fallback).
c. Domain‑Specific Scenarios
– Explain how you would secure Google API credentials in a CI/CD pipeline.
– Walk through a migration strategy from a monolithic Express app to a modular NestJS architecture.
– Describe how you would monitor and log Cloud Functions errors and correlate them with NestJS logs.
d. Behavioural Questions
– Prepare STAR stories that highlight collaboration with frontend, DevOps, and AI teams.
– Show examples of taking ownership of production incidents and implementing preventive measures.
6. Practical Steps to Get Ready Within 4–6 Weeks
Week 1
• Refresh Node.js, TypeScript and NestJS fundamentals.
• Set up local Docker environment and create a baseline NestJS project.
Week 2
• Build a simple CRUD API with PostgreSQL, add MongoDB for a secondary collection.
• Deploy the app to DigitalOcean using a CI/CD pipeline (GitHub Actions).
Week 3
• Integrate OpenAI API into a NestJS service; implement caching in PostgreSQL.
• Set up a Firebase project, write a Cloud Function that interacts with Firestore.
Week 4
• Install n8n, design two workflows (data sync and AI content generation).
• Connect the workflow to your NestJS service via webhooks.
Week 5
• Write Dockerfiles, build multi‑stage images, push to Docker Hub.
• Harden CI/CD: add lint, test, security scanning (Snyk), and automated deployment.
Week 6
• Polish GitHub repos, add README, diagrams, and demo videos.
• Conduct mock interviews (coding, design, behavioral) with peers or using platforms like Interviewing.io.
7. Final Checklist Before Application
– Updated resume highlighting 3–5 years of relevant experience, specific tools (Node.js, NestJS, OpenAI, n8n, Firebase, Docker, CI/CD).
– Clear LinkedIn profile with keywords matching the job description.
– Portfolio links (GitHub repos, demos, blog posts).
– Brief cover letter that ties your AI‑integration projects and workflow automation experience to the company’s needs.
By systematically strengthening each technical pillar, showcasing real‑world integrations, and rehearsing the interview scenarios, you’ll be well‑positioned to meet the expectations of this Backend Developer role. Good luck!
1. Understand the Job Context
• The role focuses on building, optimizing and scaling cloud‑based backend services.
• Core technologies: Node.js, NestJS, TypeScript, Express.js.
• Key integrations: OpenAI / LangChain (or similar AI tools), n8n (or Zapier/Airflow), Firebase, Firestore, Google Cloud Functions, Google APIs, Docker, CI/CD pipelines.
• Databases: MongoDB and PostgreSQL – both the data model and performance tuning are critical.
• Deployment platforms: DigitalOcean and Google Cloud (Firebase).
2. Technical Skill Deep‑Dive
a. Node.js / NestJS / TypeScript
– Review the NestJS architecture (modules, providers, controllers, interceptors, guards).
– Practice building RESTful APIs and GraphQL resolvers in NestJS.
– Master TypeScript features (generics, utility types, decorators).
– Implement middleware, custom pipes and exception filters for robust error handling.
b. Express.js (for legacy code or micro‑services)
– Refresh routing, middleware chaining, error handling, and request/response lifecycle.
c. Databases
– MongoDB: schema‑design with Mongoose, aggregation pipelines, indexing strategies, sharding basics.
– PostgreSQL: relational modeling, advanced SQL (CTE, window functions), query optimisation, partitioning.
– Practice migrations (typeORM or Prisma) and transaction handling in both databases.
d. AI Integration (OpenAI, LangChain)
– Sign up for OpenAI API, explore completions, embeddings, assistants, function calling.
– Build a small prototype that calls the API from a NestJS service, handles rate limits, and caches results.
– Review LangChain concepts: chains, agents, memory, retrievers. Create a simple chain that queries a vector store built on PostgreSQL.
e. Workflow Automation (n8n)
– Install n8n locally or use the cloud version.
– Design a workflow that pulls data from a PostgreSQL table, processes it via a custom Node.js function, and writes the result back to Firestore.
– Familiarize yourself with webhooks, triggers, and the n8n API for programmatic workflow creation.
f. Firebase / Firestore / Google Cloud Functions
– Set up a Firebase project, enable Firestore in native mode, write security rules.
– Deploy a simple Cloud Function (HTTP trigger) that writes data to Firestore.
– Explore background triggers (onCreate, onUpdate) and integrate them with NestJS services via REST or gRPC.
g. Google APIs (Drive, Maps, Sheets, etc.)
– Create a Google Cloud Service Account, enable needed APIs, generate OAuth credentials.
– Write a NestJS service that authenticates with Google and reads/writes a Google Sheet.
– Experiment with the Maps Geocoding API for address validation in a sample endpoint.
h. Containerisation and CI/CD
– Write a Dockerfile for a NestJS app (multi‑stage build, non‑root user).
– Compose a docker‑compose.yml that brings up MongoDB, PostgreSQL and the NestJS container.
– Set up a simple GitHub Actions workflow: lint → test → build → push Docker image → deploy to DigitalOcean (App Platform) or Firebase Hosting (via firebase-tools).
i. Version Control & Collaboration
– Practice rebasing, squashing commits, and pull‑request workflow.
– Configure branch protection rules, code‑owners and automated code‑review bots.
3. Build a Relevant Portfolio
• Create at least two public GitHub repositories:
1. A full‑stack mini‑project using NestJS, PostgreSQL, and a GraphQL API, with Dockerised deployment to DigitalOcean.
2. An AI‑augmented service that integrates OpenAI (or LangChain) with n8n for automated content generation, persisting results in Firestore.
• Document each project with a concise README, architecture diagram, API specs (OpenAPI), and a short video demo.
• Write a technical blog post (Medium, Dev.to) describing a challenging integration you solved—e.g., “Caching OpenAI embeddings in PostgreSQL for real‑time recommendation”.
4. Certifications and Courses (optional but advantageous)
– Node.js Certified Developer (OpenJS)
– NestJS Advanced Training (Udemy or official NestJS workshops)
– Google Cloud Associate Engineer (covers Cloud Functions, IAM, APIs)
– MongoDB University – Performance & Indexing course
– OpenAI API Quickstart (official documentation)
5. Interview Preparation
a. Coding Rounds
– Solve problems on platforms that emphasize TypeScript (LeetCode, HackerRank, Codeforces).
– Practice data‑structure questions that involve real‑world scenarios, such as “Design a rate‑limited API gateway” or “Implement a pagination system for a large MongoDB collection”.
b. System Design
– Prepare for designing a scalable backend for an AI‑driven chatbot: discuss API gateway, authentication (JWT/OAuth), async processing (queues, n8n), data storage choices (PostgreSQL for structured data, MongoDB for logs), cache layer (Redis), and deployment (Docker on DigitalOcean).
– Review CAP theorem, eventual consistency, and techniques to handle AI latency (circuit breaker, fallback).
c. Domain‑Specific Scenarios
– Explain how you would secure Google API credentials in a CI/CD pipeline.
– Walk through a migration strategy from a monolithic Express app to a modular NestJS architecture.
– Describe how you would monitor and log Cloud Functions errors and correlate them with NestJS logs.
d. Behavioural Questions
– Prepare STAR stories that highlight collaboration with frontend, DevOps, and AI teams.
– Show examples of taking ownership of production incidents and implementing preventive measures.
6. Practical Steps to Get Ready Within 4–6 Weeks
Week 1
• Refresh Node.js, TypeScript and NestJS fundamentals.
• Set up local Docker environment and create a baseline NestJS project.
Week 2
• Build a simple CRUD API with PostgreSQL, add MongoDB for a secondary collection.
• Deploy the app to DigitalOcean using a CI/CD pipeline (GitHub Actions).
Week 3
• Integrate OpenAI API into a NestJS service; implement caching in PostgreSQL.
• Set up a Firebase project, write a Cloud Function that interacts with Firestore.
Week 4
• Install n8n, design two workflows (data sync and AI content generation).
• Connect the workflow to your NestJS service via webhooks.
Week 5
• Write Dockerfiles, build multi‑stage images, push to Docker Hub.
• Harden CI/CD: add lint, test, security scanning (Snyk), and automated deployment.
Week 6
• Polish GitHub repos, add README, diagrams, and demo videos.
• Conduct mock interviews (coding, design, behavioral) with peers or using platforms like Interviewing.io.
7. Final Checklist Before Application
– Updated resume highlighting 3–5 years of relevant experience, specific tools (Node.js, NestJS, OpenAI, n8n, Firebase, Docker, CI/CD).
– Clear LinkedIn profile with keywords matching the job description.
– Portfolio links (GitHub repos, demos, blog posts).
– Brief cover letter that ties your AI‑integration projects and workflow automation experience to the company’s needs.
By systematically strengthening each technical pillar, showcasing real‑world integrations, and rehearsing the interview scenarios, you’ll be well‑positioned to meet the expectations of this Backend Developer role. Good luck!