What to Prepare for a Tech Interview

If you're getting ready for a technical interview, it's important to understand that just knowing how to code is no longer enough.

Below, I share the key areas you need to master, based on my experience working with companies like SproutLoud, Ansira, Imaginamos, and more.

✅ 1. Have a short elevator pitch ready (45–60 seconds)

"I'm Rubén Rangel, a Full-Stack developer with 18 years of experience, mainly strong in PHP, JavaScript, Vue.js, Angular, Laravel, and NestJS. I enjoy building systems from scratch and I'm passionate about clean code, system design, and performance. I've led the full architecture of projects like Indigos Network, and I currently contribute to platforms at SproutLoud and Ansira that integrate marketing and automation at scale."

📌 Don't go on too long—they will ask you more questions later.

✅ 2. Prepare for questions about specific technologies

Can you tell me about your experience working with PHP, Python, JavaScript (React, Angular, or Vue)? What’s your strongest skill?

I have over 18 years of experience with JavaScript, including frameworks like Vue.js and Angular.
Vue.js is my strongest area, followed by Angular (up to version 9).
I’ve used Vue.js extensively for dashboards and dynamic interfaces, and Angular for complex enterprise apps.

I’ve also worked with Python for web scraping, backend services (PHP), REST APIs, and automation tasks.

I don’t have production experience with C#.

✅ Always be honest.

✅ 3. Clearly explain your experience in software architecture

Have you designed and led the technical architecture of a software product? Can you give an example?

Yes. At Indigos Network, I was responsible for designing and implementing the entire architecture of a purchasing platform that connects clients with suppliers. It included:

• Modular backend in Laravel with domain-based structure
• Frontend in Angular 9
• Real-time notifications using Firebase
• Infrastructure deployed on AWS (EC2, S3)
• RESTful API and authentication layers
• CI/CD automation and cloud deployment

I led decisions on the database schema, system scalability, and infrastructure setup at companies like Ormigga SAS, Tres Astronautas, Imaginamos, and Ansira.

Prepare 1 or 2 real architecture examples you've designed

Focus on:

🟨 Example 1: B2B Purchasing Platform for Companies (Ormigga)

Technology used:

• Backend: PHP with Laravel 5.6 (later upgraded to 7.x)
• Frontend: Angular 6 (upgraded to 9)
• Database: MySQL
• Realtime/Notifications: Firebase
• Cloud: AWS (EC2, S3, Route 53)

System scalability:

To support user and transaction growth, I designed the architecture using AWS services. We used EC2 with autoscaling to handle traffic spikes, S3 for file storage, and Route 53 for load balancing and DNS. I modularized the backend into separate services (auth, purchases, suppliers), which allowed for horizontal scaling.

Key decisions I made:

• Led the migration from Laravel 5.6 to 7.x, improving performance and compatibility
• Upgraded the frontend from Angular 6 to 9 to take advantage of Ivy and faster load times
• Implemented granular roles and permissions in the backend to control purchase approval flows
• Used Firebase to implement a real-time notification system and chat between client and supplier

Problem it solved:

The company needed to digitize and scale its corporate purchasing process. Everything was manual before. The system enabled automation of the relationship between suppliers and buyers, budget control, cost optimization, and better traceability.

The platform needed to process and deliver personalized marketing campaigns to thousands of brand partners across multiple channels. My work helped make this logic more robust and scalable, ensuring performance and reliability for high-volume and high-priority campaigns. -->

✅ 4. Frequently Asked Interview Questions

🧠 How many years of experience do you have in digital transformation?

I have over 18 years of experience in digital transformation, especially in SaaS products.
For example, at Indigos Network, Imaginamos, SproutLoud, and Ansira, I led projects that replaced manual processes with complete web systems (dashboards, workflows, reports, APIs).
These efforts helped reduce human errors, save operational time, and centralize business data.

💬 Have you worked directly with clients in consulting or custom development environments?

Yes, I’ve worked directly with clients in multiple custom development agencies, including Indigos Network, Videobase, Imaginamos, and Tres Astronautas.
I always aim to translate technical terms into business value: I explain decisions based on benefits, use diagrams, and validate their needs with prototypes or user stories before developing.

💰 What is your salary expectation in USD?

I’m open to discussing fair compensation based on the role's responsibilities.
Based on my experience and the market, my target range is between $XXXXX and $XXXXX USD per year.

🇬🇧 English Level
📖✍️ Fluent in reading and writing (C1).
🧑‍💼💬 Comfortable handling meetings and asynchronous communication.
🗣️ Currently improving my spoken English (B2) and progressing quickly towards full fluency (C1).

🛠️ Key Technologies

Languages: JavaScript, TypeScript, PHP, Python, SQL
Frameworks: Vue.js, Angular, NestJS, Laravel, Django
Backend: Node.js, REST APIs, GraphQL
Databases: PostgreSQL, MySQL, MongoDB, DynamoDB
Cloud & DevOps: AWS (EC2, S3, RDS, Lambda, Fargate), Firebase, Docker, Redis
Others: TDD, SOLID, DDD, OAuth2, Git, Linux, WordPress
Soft skills: Leadership, Agile/Scrum, Client Communication, Code Review

🧭 Know Yourself

Strengths and Weaknesses

✅ I have over 18 years of experience with PHP and JavaScript, which allows me to confidently handle complex projects.
💬 I know how to gather requirements directly from clients and translate them into effective technical solutions.
🧠 When I need to work with technologies I'm not familiar with, I use Artificial Intelligence to find accurate and efficient paths to meet the requirements without wasting time.
⚙️ I haven't worked with Flask or React in production, but I have solid experience with NestJS and Vue.js, and I learn new frameworks quickly when needed.

🎯 Smart Questions for the End of the Interview

• How is the engineering team structured in this role?
• What challenges is the product currently facing?
• What technologies do you plan to adopt or evolve over the next year?

🧱 Scalable Architecture Design (Frontend + Backend + Data + AI)

1. Frontend

• SPA built with React or Vue 3
• Tailwind CSS to keep the code clean and maintainable
• Internationalized content (i18n)
• SEO optimized with prerendering or SSR (Next.js)
• Integration with a secure and managed API Gateway

2. Backend

• Microservices using Laravel (PHP) or Spring Boot
• Communication via events or queues (Kafka or RabbitMQ)
• Orchestration in Kubernetes (EKS or GKE)
• Authentication: OAuth2 with Laravel Passport or Auth0
• CI/CD: GitLab Pipelines with testing, security, and automatic deployment

3. Data

• Transactional database: PostgreSQL with replication and partitioning
• Data lake in AWS S3 to store events, logs, and training datasets
• Streaming and ETL: Kafka + Apache Flink
• Dashboarding: Metabase or Apache Superset

4. AI / ML

• Python (FastAPI) to expose trained models as microservices
• Training with scikit-learn or TensorFlow, using pipelines in AWS SageMaker or Vertex AI
• Anonymized and versioned data using DVC or MLflow
• Models acting as internal services or asynchronously via queues

🚀 Scalability and Observability

• 📈 Horizontal autoscaling per service with Kubernetes + HPA
• 📊 Observability with Prometheus + Grafana
• 🕵️‍♂️ Tracing with Jaeger
• 📄 Logs with the ELK Stack
• 🧩 Event-driven architecture to decouple services

🧠 Key Decisions

• ✅ Choose Laravel
• 🧠 Separate AI into its own domain to isolate complexity
• 📬 Use queues and cache (Redis) to decouple expensive processes

🔍 Differences Between Monolith, Microservices, and Event-Driven Architecture

☁️ Using AWS in Scalable Architectures

I have worked directly with key AWS services to build and scale robust applications in production:

1️⃣ EC2 (Elastic Compute Cloud)

• 🚀 Host backend servers in production and staging
• ⚙️ Set up autoscaling + load balancers (ELB)
• 🔁 Automate deployments with CI/CD

2️⃣ Lambda

• 🖼️ Image processing when uploading to S3
• 🔔 Send asynchronous notifications
• ✅ Run validations on specific forms

3️⃣ S3 (Simple Storage Service)

• 📁 Store attachments, media content, and backups
• 🔐 Configure secure access policies and enable versioning

4️⃣ RDS (Relational Database Service)

• 💾 I use MySQL and PostgreSQL
• 📊 Set up read replicas and automatic backups
• 🌐 High availability with multi-AZ instances

5️⃣ API Gateway

• 🔒 Expose secure endpoints to microservices or Lambdas
• ⚠️ Set up throttling and authentication (JWT / Cognito)

6️⃣ Other key components

• 📡 CloudWatch: Logs and custom alerts
• 🌍 Route 53: DNS and health checks
• 🔐 IAM: Minimum necessary permissions
• 📬 SQS: Queues to decouple heavy processes (reports, emails)

🔐 How to protect sensitive information in distributed systems

In distributed systems involving multiple services, environments, and users, protecting sensitive information is a top priority. These are the strategies I apply:

1️⃣ Encryption

• 🔒 In transit:
  I use HTTPS/TLS for all communication between services, frontend, and APIs.
  Example: API Gateway + ACM certificates in AWS.

• 🗄️ At rest:
  I enable AES-256 encryption in databases (RDS), storage (S3), and backups.
  I also encrypt sensitive data in the app before storing it (e.g., tokens or card numbers).

2️⃣ Secret management

• 🧪 I use AWS Secrets Manager or Parameter Store to manage keys, passwords, tokens, and credentials.
• ❌ I avoid exposing sensitive data in environment variables or code.

3️⃣ Access control

• 🛡️ I apply the principle of least privilege using IAM for services and users.
• 🔐 I use OAuth2 / JWT to authorize access between systems and define scopes.
• 🧩 I separate environments (dev, staging, prod) with distinct roles and policies.

4️⃣ Traceability and auditing

• 📋 I log access and actions in CloudWatch, log systems (ELK stack), or tools like Datadog.
• 🔍 I audit changes to sensitive data (users, finances, permissions).

5️⃣ Validation and sanitization

• ⚠️ I apply strict validation and sanitization to prevent attacks (SQL injection, XSS).
• 🔁 I validate both on the frontend and in the APIs.

6️⃣ Incident response

• 🚨 I set up alerts for unusual access or security errors.
• 🔁 I have a key rotation and recovery plan in case of exposure.

🛡️ Security in modern systems: OAuth2, access roles, and encryption

🔑 OAuth2

• In projects like Ormigga, I used Laravel Passport to implement OAuth2.
• I issue access tokens with defined scopes.
• I use JWT as the token format to validate permissions without querying the database.

👥 Access roles

👥 Access roles
🔐 I design authentication systems with hierarchical roles like Admin, Editor, and User, adapting them to business needs.
⚖️ I make sure each role only has access to what's necessary, following best practices for security and user experience.
🛠️ I’ve implemented these role schemes both in systems built from scratch and in existing platforms.

🛡️ Secure design best practices (OWASP principles)

In every system I design or maintain, I apply OWASP project principles to mitigate common risks and ensure security from the architecture level.

✅ 1. Strict input validation

• I never trust data coming from the client
• I use server-side validation (Laravel Requests) and sanitization to avoid injections (SQL, XSS)

🔐 2. Authentication and session management

• I implement strong authentication (OAuth2, JWT)
• I use token expiration, revocation, and inactive session detection
• I protect against brute-force attacks by limiting login attempts

🔒 3. Role-based authorization

• I use RBAC with detailed permission control
• Each endpoint checks the user's role before allowing the action (principle of least privilege)

🔏 4. Strong encryption

• Encryption in transit (TLS 1.2/1.3) for all communication
• Encryption at rest in databases and storage (AES-256)
• Passwords are stored using bcrypt or argon2

🚫 5. Secure error handling

• I don’t expose traces, internal details, or sensitive messages to users
• Errors are logged internally for auditing without compromising security

🔐 6. Secure defaults

• All features start from a secure posture: access is denied unless explicitly allowed
• I disable unused endpoints or configurations (e.g., debug in production)

🛑 7. CSRF and XSS protection

• In Laravel, I enable CSRF middleware for forms
• I use Content-Security-Policy and properly escape dynamic data in the frontend

🤖 Use of AI / LLMs in modern systems

I’ve started integrating Artificial Intelligence and large language models (LLMs) into web systems to automate tasks, enhance user experience, and offer advanced features.

💡 Use cases

• 📝 Automated content generation (descriptions, support replies, email drafts)
• 💬 Internal assistants for clients or providers (e.g., guided chatbots)
• 🏷️ Information classification (automatic tags, intent detection)
• 🎯 Personalized recommendations based on user behavior

🛠️ Technologies used

• OpenAI API (GPT-4): for natural language tasks, integrated via backend in Laravel or Python microservice (FastAPI)
• Hugging Face Transformers: for local inference in controlled environments where confidentiality is required
• Python (scikit-learn, pandas, spaCy): for lightweight NLP or classification models
• AWS S3 and RDS: to store training and inference datasets

🧩 Integration into architecture

• Models are exposed as REST microservices or integrated via queues (SQS/Kafka) for asynchronous processes
• For sensitive tasks, I anonymize and clean data before sending it to external services
• I use logs and metrics to evaluate response quality and detect errors

🌍 Experience working with clients on real-world projects

Throughout my career, I’ve worked with various clients in countries like 🇻🇪 Venezuela, 🇨🇴 Colombia, 🇪🇸 Spain, and 🇨🇱 Chile, in companies such as Gaviria Software, Videobase, Indigos Network, Tres Astronautas, and Ormigga SAS, participating in the development of custom, scalable technology solutions aligned with real business goals.

🚀 Notable examples:

• 📺 Videobase: Developed custom streaming platforms, optimizing video upload and delivery using AWS S3 and CloudFront
• 🏢 Ormigga SAS: B2B purchasing platform with budget control, approval workflows, client-provider chat, and cloud storage (EC2, S3, RDS)
• 📣 Indigos Network: Marketing campaign automation for multiple brands, integrating third-party APIs and event-driven workflows
• 💼 Gaviria Software: Robust backend development with Laravel and PostgreSQL for financial control and licensing systems
• 👨‍🚀 Tres Astronautas: Frontend projects with Angular and backend with NodeJS/NestJS for SaaS products

In all these projects, I not only participated as a developer but also made architectural decisions, defined integration flows, optimized cloud resources, and ensured security best practices (🔒 OWASP, OAuth2, encryption).

🧠 Effective communication: from technical design to business understanding

One of my strengths as a senior developer has been translating complex technical solutions into understandable explanations for different audiences: from product managers and QA teams to non-technical stakeholders.

🛠️ How do I communicate solutions?

1. ✅ Clear user stories

   • I start from the business objective and break it down into well-defined features
   • This helps align the team at the start of each sprint

2. 🧾 Visuals and diagrams

   • I use architecture diagrams, integration flows, database schemas, and sequence diagrams to explain how systems or services interact

3. 🗣️ Audience-adapted language

   • I use technical terms when needed, but I know when to simplify to focus on benefits, workflows, or risks, depending on who I’m speaking with

🔹 Ormigga

• I visualized the full purchase order flow for different roles (buyer, supplier, financial manager) with real examples and scenarios
• This reduced friction in the approval process and allowed validating the solution before full development was completed

🚀 Use cases for NestJS, Laravel, Docker, and AWS

🧱 NestJS

I’ve used NestJS in several projects, for example in Tres Astronautas, where I developed a REST API for property management. There, I applied:

• ✅ Modular architecture
• ✅ Dependency injection
• ✅ Use of DTOs and Guards
• ✅ Unit testing with Jest

🛠 Laravel

I’ve worked extensively with Laravel, including:

• In Ormigga: I designed the full architecture of a B2B purchasing platform with:
  • 🔐 User roles
  • 📣 Real-time notifications
  • ✅ Multi-step approval flow
• Implementation of:
  • 🔗 RESTful API
  • 🛡 OAuth2 authentication
  • ⚙️ Job queues
  • 🧪 Testing with PHPUnit

🐳 Docker

• Defined consistent development and deployment environments
• Projects with microservices using Laravel and NodeJS
• 🔧 Used Docker Compose for local orchestration
• 📦 Optimized images for production

☁️ AWS

I’ve worked with multiple Amazon Web Services:

• 🖥 EC2: Auto-scaled servers for critical applications
• 🗂 S3: File, image, and backup storage
• 🛢 RDS: PostgreSQL and MySQL databases with high availability
• ⚡ Lambda: Serverless functions for specific tasks
• 📊 DynamoDB: For NoSQL workloads and fast queries
• 🐳 ECS Fargate: Run containers without managing servers
• 🛠 Infrastructure as Code (IaC) for reproducible environments

All of this allows me to deliver robust, scalable, and well-maintained solutions 💪.