Software Engineering Tools You Need to Know for Technical Interviews in 2025

During a technical interview at a fast-growing startup, I watched a candidate solve a complex algorithm problem perfectly. Then the interviewer asked: "Can you show me how you'd debug this if it wasn't working in production?" The candidate stared at the screen, unsure where to start. No breakpoints, no logging strategy, no understanding of how to investigate issues in a real environment. They didn't get the offer.

Technical interviews aren't just about algorithms and data structures anymore. Companies want to know if you can actually ship code, debug production issues, and work effectively with modern development tools. Here's what you need to know in 2025.

Why Tool Knowledge Matters in Interviews

When I interview candidates now, I care less about whether they can invert a binary tree on a whiteboard and more about whether they can work productively on day one. Tool proficiency is a proxy for real-world experience.

The shift in technical interviews:

Companies are moving away from pure algorithmic puzzles toward practical assessments. You might be asked to debug a broken application, set up a development environment, or demonstrate your workflow. If you fumble with basic Git commands or don't know how to use a debugger, it signals you haven't built much outside of tutorials.

Tool knowledge reveals experience level:

A junior developer might know git add and git commit. A mid-level developer understands branching strategies and can resolve merge conflicts. A senior developer knows how to rewrite history with git rebase, use git bisect to find bugs, and has opinions on trunk-based development versus GitFlow. Your tool fluency tells interviewers exactly how much hands-on experience you have.

Git: The Non-Negotiable Baseline

Every software engineering interview assumes you know Git. Not just the happy path—they want to see if you can handle the messy reality of collaborative development.

Commands You Absolutely Must Know

Basic workflow:

git status                    # Check what's changed
git add <file>               # Stage specific files
git add .                    # Stage everything (use carefully)
git commit -m "message"      # Commit with message
git push origin <branch>     # Push to remote
git pull origin <branch>     # Pull latest changes

These are table stakes. If an interviewer sees you googling these, that's a red flag.

Branching and merging:

git branch feature-name           # Create new branch
git checkout feature-name         # Switch to branch
git checkout -b feature-name      # Create and switch in one command
git merge feature-name            # Merge branch into current branch
git branch -d feature-name        # Delete local branch

In interviews, you might be asked: "How would you work on a new feature without disrupting the main branch?" The answer starts with creating a feature branch.

The commands that separate good from great:

# Undo your last commit but keep the changes
git reset --soft HEAD~1

# Discard uncommitted changes (dangerous!)
git checkout -- <file>

# See commit history
git log --oneline --graph --all

# Find which commit introduced a bug
git bisect start
git bisect bad                # Current version has the bug
git bisect good <commit>      # This older commit was fine
# Git will binary search through commits

# Cherry-pick a specific commit from another branch
git cherry-pick <commit-hash>

# Stash changes temporarily
git stash
git stash pop                 # Reapply stashed changes

# Interactive rebase to clean up history
git rebase -i HEAD~3          # Edit last 3 commits

Interview scenario you might encounter:

"You committed sensitive API keys to the repository. How do you remove them from Git history?"

Weak answer: "I'd delete them and commit again."

Strong answer: "I'd use git filter-branch or the BFG Repo-Cleaner to remove the file from all commits in history. Then I'd force push to the remote repository and immediately rotate those API keys since they're now compromised. I'd also add that file pattern to .gitignore and set up a pre-commit hook to prevent this in the future."

This answer shows you understand Git history, security implications, and preventive measures.

Merge Conflicts: The Real Test

When interviewers ask about merge conflicts, they're checking if you've worked on real teams. Here's how to handle them confidently:

# You'll see conflict markers in files:
<<<<<<< HEAD
const apiUrl = 'https://api.staging.example.com';
=======
const apiUrl = 'https://api.production.example.com';
>>>>>>> feature-branch

Walk through your thought process: "I'd look at both changes, understand why each person made their change, and choose the correct version or combine them. In this case, I'd check with the teammate who made the production change to understand the context. We probably need a config file to handle different environments rather than hardcoding the URL."

This shows technical knowledge plus communication skills.

Terminal/Command Line Proficiency

Developers who are comfortable in the terminal work faster. Interviewers notice when you reach for the GUI for everything.

Essential Commands for Interviews

File and directory operations:

ls -la                    # List all files including hidden
cd /path/to/directory     # Change directory
cd ..                     # Go up one directory
pwd                       # Print working directory
mkdir new-folder          # Create directory
touch newfile.txt         # Create empty file
rm file.txt              # Remove file
rm -rf folder/           # Remove directory and contents (dangerous!)
cp source.txt dest.txt   # Copy file
mv old.txt new.txt       # Move/rename file

Searching and finding:

# Find files by name
find . -name "*.js"

# Search file contents
grep -r "TODO" .                    # Recursive search
grep -r "function" --include="*.js" # Only in JS files

# Count lines of code
find . -name "*.js" | xargs wc -l

Process management:

ps aux                    # List all running processes
ps aux | grep node       # Find Node processes
kill <PID>               # Terminate process
kill -9 <PID>            # Force kill
top                      # Monitor system resources
htop                     # Better version of top (if installed)

Network commands:

curl https://api.example.com/users     # Make HTTP request
curl -X POST -H "Content-Type: application/json" \
  -d '{"name":"John"}' https://api.example.com/users

netstat -tuln            # Show listening ports
lsof -i :3000           # What's using port 3000?

Interview scenario:

"Your Node.js application is already running on port 3000, but you forgot to shut it down. How do you kill it?"

lsof -i :3000           # Find the process ID
kill -9 <PID>           # Kill it
# Or one-liner:
lsof -ti :3000 | xargs kill -9

Shell Shortcuts That Show Proficiency

Knowing these shortcuts during a live coding session subtly signals experience:

Ctrl + C        # Cancel current command
Ctrl + D        # Exit terminal
Ctrl + L        # Clear screen (same as 'clear')
Ctrl + R        # Search command history (then type to search)
Ctrl + A        # Jump to beginning of line
Ctrl + E        # Jump to end of line
Ctrl + U        # Delete from cursor to beginning
Ctrl + K        # Delete from cursor to end
!!              # Repeat last command
sudo !!         # Repeat last command with sudo

Docker: The Modern Standard

In 2025, if you're interviewing for anything beyond a junior role, you need Docker knowledge. Companies use containerization everywhere.

Core Concepts to Explain

What is Docker and why do we use it?

Strong answer: "Docker packages an application with all its dependencies into a container. This solves the 'works on my machine' problem. The same container that runs on my laptop will run identically in staging and production. It also makes it easy to run multiple isolated services—like a database, Redis cache, and Node server—all configured the same way across the team."

This answer shows you understand the value proposition, not just the mechanics.

Commands Interviewers Expect You to Know

Image management:

docker pull nginx                    # Download an image
docker images                        # List local images
docker rmi <image-id>               # Remove image
docker build -t myapp:latest .      # Build image from Dockerfile

Container operations:

docker ps                           # List running containers
docker ps -a                        # List all containers
docker run -d -p 3000:3000 myapp   # Run container (detached, port mapping)
docker stop <container-id>         # Stop container
docker rm <container-id>           # Remove container
docker logs <container-id>         # View container logs
docker exec -it <container-id> bash # Enter running container

Docker Compose for multi-container apps:

docker-compose up                   # Start services defined in docker-compose.yml
docker-compose up -d                # Start in detached mode
docker-compose down                 # Stop and remove containers
docker-compose logs -f              # Follow logs
docker-compose ps                   # List running services

Real Interview Question

"Walk me through setting up a development environment for a Node.js API with a PostgreSQL database."

Strong answer with Dockerfile:

# Dockerfile
FROM node:18-alpine

WORKDIR /app

COPY package*.json ./
RUN npm ci --only=production

COPY . .

EXPOSE 3000
CMD ["node", "server.js"]

And docker-compose.yml:

version: '3.8'
services:
  api:
    build: .
    ports:
      - "3000:3000"
    environment:
      DATABASE_URL: postgres://user:pass@db:5432/mydb
    depends_on:
      - db
    volumes:
      - ./:/app
      - /app/node_modules

  db:
    image: postgres:15
    environment:
      POSTGRES_USER: user
      POSTGRES_PASSWORD: pass
      POSTGRES_DB: mydb
    volumes:
      - postgres-data:/var/lib/postgresql/data
    ports:
      - "5432:5432"

volumes:
  postgres-data:

Then explain: "I'd run docker-compose up and the API would connect to the database automatically. The volume mount for the app directory means I can edit code locally and it reflects immediately. The postgres-data volume persists database data between container restarts."

This demonstrates practical knowledge of Docker in real development workflows.

Debugging: The Skill That Reveals Experience

Anyone can write code that works when they test it themselves. Experienced developers can figure out why code doesn't work in environments they've never seen.

Browser DevTools (for frontend developers)

Console debugging:

console.log('value:', value)              // Basic output
console.table(arrayOfObjects)             // Formatted table
console.time('operation')                 // Start timer
// ... code ...
console.timeEnd('operation')              // End timer
console.trace()                           // Stack trace

Debugger statement:

function calculateTotal(items) {
  debugger;  // Execution will pause here when DevTools open
  return items.reduce((sum, item) => sum + item.price, 0);
}

Network tab insights:

Interview question: "The API call is failing but your code looks correct. How do you debug it?"

Walk through: "I'd open DevTools Network tab and look at the failing request. I'd check:

1. The request URL—is it correct?
2. Request headers—am I sending the auth token?
3. Request payload—is the data formatted correctly?
4. Response status code—401 suggests auth issue, 500 is server error, 400 is bad request
5. Response body—often contains error details

I'd also check the Console for any CORS errors, which are common with API calls."

Backend Debugging Strategies

Node.js debugging:

# Built-in debugger
node inspect server.js

# Chrome DevTools debugging
node --inspect server.js
# Then open chrome://inspect in Chrome

# VS Code debugging - add to launch.json
{
  "type": "node",
  "request": "launch",
  "name": "Debug Server",
  "program": "${workspaceFolder}/server.js"
}

Logging best practices:

// Bad: No context
console.log(user);

// Good: Context and structure
console.log('User authentication attempt:', {
  userId: user.id,
  email: user.email,
  timestamp: new Date().toISOString()
});

// Even better: Use a logging library
logger.info('User authentication attempt', {
  userId: user.id,
  email: user.email
});

Interview scenario:

"Your API is returning 500 errors but only in production, not locally. How do you investigate?"

Strong approach:

1. "First, I'd check the production logs for the error message and stack trace
2. Look for differences between local and production—environment variables, database data, Node version
3. If logs aren't detailed enough, I'd add more logging around the failing code and redeploy
4. Use production monitoring tools (DataDog, Sentry) to see when the error started
5. Check if it's related to specific inputs by examining recent API requests
6. If safe, try to reproduce with production data in a staging environment"

IDE Proficiency: Working at Professional Speed

Your choice of IDE matters less than knowing it deeply. But you should know some IDE well.

VS Code Shortcuts That Matter

Navigation:

Cmd/Ctrl + P           # Quick file open (fuzzy search)
Cmd/Ctrl + Shift + P   # Command palette
Cmd/Ctrl + Shift + F   # Search across all files
Cmd/Ctrl + D           # Select next occurrence
Cmd/Ctrl + /           # Toggle comment
Alt + Up/Down          # Move line up/down
Alt + Shift + Up/Down  # Duplicate line
Cmd/Ctrl + Shift + L   # Select all occurrences

Multi-cursor editing:

This is powerful to demonstrate in interviews. If you need to edit multiple similar lines:

• Alt + Click to place multiple cursors
• Cmd/Ctrl + Alt + Up/Down to add cursors above/below

Refactoring:

• F2 to rename symbol across entire codebase
• Right-click → "Extract to function" or "Extract to variable"

Essential Extensions

For interviews, mention you use extensions that boost productivity:

• ESLint/Prettier: "Automated formatting and linting catch issues before code review"
• GitLens: "Helps me understand who changed what and why"
• Error Lens: "Shows errors inline as I type"
• REST Client or Postman: "For testing APIs during development"

Package Managers and Dependency Management

npm/yarn Commands Beyond the Basics

Everyone knows:

npm install
npm start

Show deeper knowledge:

# Install exact version
npm install react@18.2.0

# Install dev dependency
npm install --save-dev jest

# Update dependencies
npm update

# Check for outdated packages
npm outdated

# Audit for security vulnerabilities
npm audit
npm audit fix

# Clean install (removes node_modules first)
npm ci  # Preferred in CI/CD pipelines

# Run script with environment variable
NODE_ENV=production npm start

Interview question:

"Your build is failing in CI/CD but works locally. What could be wrong?"

Strong answer: "Several possibilities:

1. Different Node versions between local and CI—I'd check the Node version in CI config
2. Package-lock.json isn't committed, so CI installed different versions—always commit lock files
3. Environment variables aren't set in CI
4. Dev dependencies are being used but CI runs npm ci --production
5. Platform-specific dependencies (Mac vs Linux) causing issues"

Environment Variables and Configuration

Understanding environment management is crucial for real applications.

.env Files

# .env (local development)
DATABASE_URL=postgresql://localhost:5432/dev_db
API_KEY=dev_key_12345
NODE_ENV=development

// Loading in Node.js
require('dotenv').config();

const dbUrl = process.env.DATABASE_URL;

Security awareness to mention:

"I never commit .env files to Git—they're in .gitignore. For sensitive values, I use environment variables in CI/CD or secret management tools like AWS Secrets Manager. I use .env.example with dummy values to document what variables are needed."

This shows you understand security, which is critical.

Testing Tools and Strategies

In 2025, knowing testing tools isn't optional for mid-level and senior roles.

Jest (JavaScript/TypeScript)

// Basic test
describe('calculateTotal', () => {
  test('sums up item prices', () => {
    const items = [
      { name: 'Coffee', price: 5 },
      { name: 'Muffin', price: 3 }
    ];
    expect(calculateTotal(items)).toBe(8);
  });

  test('returns 0 for empty array', () => {
    expect(calculateTotal([])).toBe(0);
  });
});

Commands:

npm test                    # Run all tests
npm test -- --watch        # Watch mode
npm test -- --coverage     # Coverage report

Interview insight:

"I write tests as I develop—often writing the test first (TDD) helps me clarify what the function should do. I aim for testing business logic thoroughly but don't test every trivial getter/setter. I use mocks for external dependencies like database calls."

CI/CD Basics

You should understand continuous integration/deployment conceptually.

GitHub Actions example:

name: Test and Deploy
on: [push]
jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - uses: actions/setup-node@v2
        with:
          node-version: '18'
      - run: npm ci
      - run: npm test
      - run: npm run build

"This runs tests on every push. If tests pass, it builds the application. In a real pipeline, I'd add deployment steps for staging/production."

How to Actually Learn These Tools

Reading about tools isn't enough. Here's how to build real proficiency:

1. Build projects that require these tools:

Create a full-stack app with Docker containers, environment variables, and automated tests. Deploy it with GitHub Actions. You'll encounter real problems that tutorials skip.

2. Practice common scenarios:

Set up a Git repository, create a merge conflict intentionally, and resolve it. Delete something with git reset, then recover it. Break your Docker setup, then fix it. The muscle memory comes from repetition.

3. Maintain a personal "commands cheatsheet":

When you learn a new command or shortcut, add it to a markdown file in your notes. Review it weekly. The commands you use repeatedly will stick naturally.

4. Watch experienced developers work:

Pair programming sessions or recorded coding sessions show you real workflows. Notice what tools they reach for, what shortcuts they use, and how they debug issues.

5. Simulate interview pressure:

Time yourself setting up a new project from scratch: Git init, create Docker setup, install dependencies, write a simple feature with tests, commit everything. Can you do it in 20 minutes? This builds confidence for live interviews.

The Meta-Skill: Knowing What You Don't Know

In interviews, you won't know every tool perfectly. What matters is demonstrating:

Resourcefulness: "I haven't used that specific tool, but I'd start by reading the documentation and looking for examples similar to our use case."

Learning ability: "I learned Docker by converting an existing project to containers. It took a weekend, but now I understand the concepts."

Humility: "I know the basics of Kubernetes but haven't used it in production. That's something I'm actively learning."

This honesty, combined with demonstrated ability to learn, often impresses more than pretending expertise.

Bringing It All Together

When an interviewer asks "What's your development workflow?", they want to hear you naturally mention these tools:

"I start by creating a feature branch with Git. I use VS Code with ESLint to catch issues as I code. I run the application locally using Docker Compose so my environment matches production. When I hit issues, I use the debugger or add strategic console.logs to understand what's happening. I write tests for new functionality, run them with Jest in watch mode, and check coverage before committing. When the feature is done, I push to GitHub, where CI runs all tests. After code review, I merge to main and the deployment pipeline handles the rest."

This paragraph demonstrates mastery of Git, IDE, Docker, debugging, testing, and CI/CD. That's what separates candidates who get offers from those who don't.

The tools don't make you a better developer, but they're the language of professional software development. Master them, and you'll walk into interviews knowing you can contribute from day one.