Technical Interviews in 2025: How to Prepare and Land Your Dream Job

Hello HaWkers, the hiring process for developers has changed significantly in recent years. In 2025, companies are looking not only for technical skills but also for the ability to solve complex problems and work in teams.

Have you been in that situation of knowing a lot but freezing during the interview? You are not alone. Preparation is the key, and in this article I will share everything I have learned about how to stand out in hiring processes.

The Interview Landscape in 2025

The tech market has matured, and with it the hiring processes. Companies are more selective but also more transparent about what they expect.

Typical Hiring Process Structure

Common stages:

1. Resume screening - Initial analysis by HR
2. Initial interview - Conversation with recruiter (15-30 min)
3. Technical test - Asynchronous coding challenge (1-7 days)
4. Technical interview - Live coding or pair programming (1-2h)
5. System Design - For senior positions (45-60 min)
6. Behavioral - Cultural fit and soft skills (30-45 min)
7. Final interview - Manager or leadership (30-45 min)

Average duration: 2-4 weeks

Preparation For Algorithms and Data Structures

Even if you do not use them daily, algorithms are still required. Here is what to focus on.

Essential Topics

Data Structures:

• Arrays and Strings
• Hash Maps and Sets
• Stacks and Queues
• Linked Lists
• Trees (Binary, BST, Trie)
• Graphs

Algorithms:

• Two Pointers
• Sliding Window
• Binary Search
• BFS and DFS
• Dynamic Programming (basic)
• Sorting and Searching

Problem-Solving Strategy

1. UNDERSTAND the problem (5 min)
   - Read carefully
   - Ask to clarify
   - Identify inputs and outputs
   - Consider edge cases

2. PLAN the solution (5-10 min)
   - Start with brute force
   - Optimize gradually
   - Explain your reasoning

3. IMPLEMENT (15-20 min)
   - Clean and readable code
   - Clear variable names
   - Comment important decisions

4. TEST (5 min)
   - Execute mentally
   - Test with examples
   - Verify edge cases

Practical Examples

Problem 1: Two Sum

// Given an array of numbers and a target, return indices
// of two numbers that add up to the target

// Approach 1: Brute Force - O(n²)
function twoSumBrute(nums: number[], target: number): number[] {
  for (let i = 0; i < nums.length; i++) {
    for (let j = i + 1; j < nums.length; j++) {
      if (nums[i] + nums[j] === target) {
        return [i, j];
      }
    }
  }
  return [];
}

// Approach 2: Hash Map - O(n)
function twoSum(nums: number[], target: number): number[] {
  const map = new Map<number, number>();

  for (let i = 0; i < nums.length; i++) {
    const complement = target - nums[i];

    if (map.has(complement)) {
      return [map.get(complement)!, i];
    }

    map.set(nums[i], i);
  }

  return [];
}

// Explanation:
// - We traverse the array once
// - For each number, we check if the complement exists in the map
// - If yes, we found the pair
// - If no, we add the number to the map

Problem 2: Valid Parentheses

// Check if parentheses string is balanced

function isValid(s: string): boolean {
  const stack: string[] = [];
  const pairs: Record<string, string> = {
    ')': '(',
    ']': '[',
    '}': '{'
  };

  for (const char of s) {
    if (char in pairs) {
      // It is a closing bracket
      if (stack.length === 0 || stack.pop() !== pairs[char]) {
        return false;
      }
    } else {
      // It is an opening bracket
      stack.push(char);
    }
  }

  return stack.length === 0;
}

// Tests
console.log(isValid('()')); // true
console.log(isValid('()[]{}')); // true
console.log(isValid('(]')); // false
console.log(isValid('([)]')); // false
console.log(isValid('{[]}')); // true

System Design: For Senior Positions

System Design evaluates your ability to design scalable systems.

Approach Methodology

1. REQUIREMENTS (5 min)
   - Functional: What does the system do?
   - Non-functional: Scale, latency, availability

2. ESTIMATES (5 min)
   - Active users
   - Requests per second
   - Storage needed

3. HIGH-LEVEL DESIGN (10 min)
   - Component diagram
   - Data flow
   - Main APIs

4. DEEP DIVE (15-20 min)
   - Database schema
   - Technology decisions
   - Trade-offs

5. OPTIMIZATIONS (5 min)
   - Potential bottlenecks
   - Caching
   - Sharding/Partitioning

Example: URL Shortener Design

Requirements:

• Shorten long URLs to short ones
• Redirect short URLs to originals
• Basic analytics (click count)
• 100M new URLs/month
• 10:1 read/write ratio

Estimates:

• Write: 100M / (30 * 24 * 3600) = ~40 URLs/second
• Read: 400 URLs/second
• Storage 5 years: 100M * 12 * 5 * 500 bytes = ~3TB

Components:

1. Load Balancer - Distributes traffic
2. Application Servers - Business logic
3. Database - Stores mappings
4. Cache - Redis for popular URLs
5. Analytics Service - Processes metrics

Database Schema:

Field	Type	Description
id	BIGINT	Auto increment
short_code	VARCHAR(7)	Unique code
original_url	TEXT	Original URL
user_id	BIGINT	Creator (optional)
created_at	TIMESTAMP	Creation date
expires_at	TIMESTAMP	Expiration
click_count	INT	Total clicks

Short Code Generation:

• Base62 encoding (a-z, A-Z, 0-9)
• 7 characters = 62^7 = 3.5 trillion combinations
• Collision: Check in database, regenerate if exists

Trade-offs discussed:

• SQL vs NoSQL (chose SQL for consistency)
• Distributed counter vs batch updates
• CDN for global caching

Behavioral Interview: Soft Skills

Companies want to know how you work in teams and handle challenges.

STAR Method For Answers

S - Situation: Context of the scenario
T - Task: Your responsibility
A - Action: What you did
R - Result: Measurable impact

Common Questions and Example Answers

1. "Tell me about a challenging project you led"

Situation: At company X, our payment system was having
15% failures during peak hours.

Task: I was assigned to lead the investigation and fix
as tech lead of a 4-person squad.

Action:
- Implemented observability with Datadog
- Identified the problem was race condition in the database
- Refactored to use transactions and optimistic locks
- Created load tests to validate

Result: We reduced failures to 0.1% and were able to
support 3x more simultaneous transactions.

2. "How do you handle negative feedback?"

Situation: In a code review, I received harsh criticism about
the architecture of a module I created.

Task: I needed to process the feedback and decide how to proceed.

Action:
- Asked for a call to better understand the concerns
- Acknowledged valid points about excessive coupling
- Proposed a gradual refactoring plan
- Documented decisions for future reference

Result: The refactoring improved the module's testability
and created a pattern that was adopted in other projects.
The reviewer became an important mentor in my career.

3. "Describe a conflict situation with a colleague"

Situation: Another dev and I had opposite views about
using microservices vs monolith for a new project.

Task: We needed to reach a decision that benefited
the project and maintained the professional relationship.

Action:
- Suggested we document pros and cons of each approach
- Did a 2-day spike for each option
- Presented findings to the team
- Reached consensus: modular monolith initially

Result: The project was delivered on time and the
architecture decision proved correct. We built a relationship
of mutual respect based on data, not opinions.

Practical Tips For Interview Day

Before the Interview

Preparation checklist:

• Research the company and product
• Review your experience and relevant projects
• Prepare questions to ask the interviewer
• Test your camera, microphone and connection
• Have water nearby
• Choose a quiet environment

During the Interview

Communication:

• Think out loud - interviewers want to see your reasoning
• Do not be afraid to ask - clarifying is positive
• If you get stuck, go back to basics - explain what you know
• Admit when you do not know - honesty is valued

Live Coding:

• Start by writing input/output examples
• Implement simple solution first
• Refactor and optimize afterwards
• Test your code manually

Questions to Ask the Interviewer

About the position:

• What does a typical day look like in this role?
• What are the biggest challenges the team faces currently?
• How is success measured in this position?

About the team:

• What is the team size?
• How does the code review process work?
• What is the main tech stack?

About the company:

• What are the growth plans?
• How is the learning culture?
• Is there a structured career plan?

Study Resources

Practice Platforms

Algorithms:

• LeetCode - Largest problem collection
• HackerRank - Good for beginners
• CodeSignal - Used by companies
• AlgoExpert - Explanatory videos

System Design:

• SystemDesignPrimer (GitHub)
• Designing Data-Intensive Applications (book)
• ByteByteGo (YouTube)
• System Design Interview (book)

Suggested Study Schedule

If you have 4 weeks:

Week	Focus	Activities
1	Basic algorithms	2-3 problems/day, arrays, strings
2	Intermediate algorithms	Trees, graphs, basic DP
3	System Design	2 complete designs, study cases
4	Mock interviews	Simulate interviews, behavioral

If you have 2 weeks:

Week	Focus
1	Top 50 LeetCode + Basic System Design
2	Mock interviews + Behavioral prep

Common Mistakes to Avoid

Technical:

• Jumping straight to code without planning
• Not testing the solution
• Ignoring edge cases
• Optimizing prematurely

Behavioral:

• Talking too much or too little
• Not showing enthusiasm
• Criticizing previous employers
• Not asking questions

Logistical:

• Being late (even virtually)
• Avoidable technical problems
• Not researching the company
• Forgetting to thank

Offer Negotiation

If you made it this far, congratulations! Now it is time to negotiate.

What to negotiate:

• Base salary
• Bonus
• Equity/stock options
• Benefits (health plan, meal allowance)
• Remote work/flexibility
• Development budget

How to negotiate:

• Research salary ranges (Glassdoor, Levels.fyi)
• Do not accept the first offer immediately
• Negotiate in terms of total value, not just salary
• Be professional and objective

If you want to deepen your technical skills before interviews, I recommend checking out the article TypeScript 5.7: New Features to update yourself with best practices.

Let us go! 🦅