15 Best Interview Preparation Websites For Jobs at Google, Facebook

This is a List of best available resources for doing programming interview preparation for software developer job, still valid in 2021.

It starts with a simple question:

“What are the best interview preparation websites for software engineer job?”

If you have worked at one of the top tech companies, this is the most frequently asked question for sure.

Preparing with the right resources can save you time and effort. In this post, I handpicked 15 websites - divided into 3 main categories - that can make your preparation easier and more efficient.

Before Starting 

Before you jump into interview prep in various websites ensure you are ready to taking programming interview. These interview books should get you all geared up with programming interview at companies like Google. 

Once you feel you are done with books you need to start practicing the problem solving on below-mentioned sites. These sites will help you get equipped with a variety of questions and solution for them. The key idea is to practice these questions multiple times such that you can answer them faster in interview duration.

Many companies look for the approach in the problem solving and may still select you if your programming solution is not optimal, However being prepared will help you give the best possible solution in short duration. This will help you clear the interview much faster with higher confidence. The employer will also have a choice to pick the candidate with better solution therefore you have high chances of getting selected. 

Must-haves

This section introduces the most popular websites that you should check no matter what stage you're at.

1. Leetcode

Leetcode is one of the most popular websites for software engineer interviews for sure. The website provides a huge number of curated interview questions with the online judge, so you can submit solutions and check if they're correct.

Questions have similar difficulty level as Google/Facebook interview. The platform now supports various popular programming languages including C, C++, Java, Python, C#, JavaScript etc..

2. Gainlo

Gainlo is an online platform that allows people have mock interviews with employees from Google, Facebook, Linkedin and so on. The core concept of Gainlo is to provide exactly the same experience as real interviews except that peopel are free to fail and will get real feedback in the end.

A lot of people will feel nervous in an interview when someone is looking over his shoulder. The best way to overcome nervousness is actually by practice. Gainlo provides such an environment that is both intense and safe.

3. Glassdoor

Glassdoor was founded at 2007 and is a website where employees and former employees anonymously review companies and their management.

For interview preparation, you can just ignore all the other sections and search for interview questions of your target company.

The best way to use Glassdoor is always after you already have a target company, e.g. you will have a Facebook interview in a few weeks. At that point, you can spend most of your time on questions from past interviews of that company.

4. GeeksforGeeks

It's hard to define what kind of services GeeksforGeeks provides because it has almost everything you need to prepare a coding interview.

“Algo” sections have quite a few coding questions you can practice with. It's worth to note that answers are provided by the website instead of some random people, so you don't need to search for solutions.


Practice coding questions

The core of coding interview preparation is practice. In this section, I'll tell you where you can get lots of coding questions.

5. HackerRank

Hackerrank is a platform for both companies and interviewees. They provide tools to help companies conduct online coding interview. At the same time, it has resources for interviewees to prepare interviews.

In a nutshell, you can sharpen your programming skills with online challenges. Some online hackathons may also get you hired by top companies like Quora.

6. Careercup

Careerup is another website that provides almost everything for interview preparation. The interview question section allows you filter coding questions by company, category and position. It's a great place to practice coding questions from your target companies.

7. Coder Career Blog

This blog is like book! It contains a lot of interesting coding questions with detailed analysis and solutions. The author Harry He is an experienced engineer and interviewer. Most of the questions are manually selected from Google, Amazon, Facebook, Microsoft, etc..

8. Project Euler

Project Euler is a series of challenging mathematical/computer programming problems that will require more than just mathematical insights to solve. Although mathematics will help you arrive at elegant and efficient methods, the use of a computer and programming skills will be required to solve most problems.

9. TopCoder

One of the most popular online online computer programming competition platform. Competitions usually take place twice a week with price and you are also encouraged to work on problems from past competitions.

It's a little bit overkilled to use TopCoder to prepare interview as questions here are usually much harder. However, if you are able to perform well on TopCoder, a coding interview is definitely a piece of cake for you.

Tutorials

For beginners, it's recommended to take a look at these tutorials before diving into coding questions directly.

10. Interview Preparation Guide

This is an interview preparation guide for any software developer. This contains useful tips for you to get yourself ready for an interview in a short duration. Most of the tips in this free ebook (PDF format) are less commonly known and may help you reach your goals faster.

11. Interactive Websites To Learn Programming

Use interactive websites to learn and try our your programming skills on web. These websites provide your a preset environment to do programming and coding exercises in any programming language. Most of the popular programming languages like Java, Python, Ruby and more are already available to start practicing. This will save you time and hassle of setting up your personal computer for programming.

12. Algorithms: Design and Analysis

This is the online course from Coursera and taught by Stanford. For people who don’t have a solid computer science foundation or are not familiar with basic data structure/algorithms, this is one of the best starting points.

The course covered a bunch of fundamental principles of algorithm design: divide-and-conquer methods, graph algorithms, practical data structures (heaps, hash tables, search trees), randomized algorithms, and more.

13. Big-O Cheat Sheet

One of my favorite preparation website. You will be surprised about how many people are confused about big-O annotation. This website summarizes everything for you.

14. Codewars

Codewars is website that helps you sharpen your programming skills with real code challenges. As you can see, the platform now supports quite a few languages including Python, C#, Java, JavaScript etc..

15. Hacking a Google Interview

This is materials from an MIT course that teaches you how to hack a Google interview.

Materials are very detailed and show you how you can nail every programming question. For each classic question, it gives you detailed tips that teach you how to come up with the right solution step by step. The solution itself is not important, you should try to generalize techniques used in the tutorial and apply them to other interview questions.

16. The Technical Interview Cheat Sheet

This is the best summary of computer science course for sure! If you don't know what basic knowledge is needed for a technical interview, you should definitely check this cheat sheet.

The cheat sheet is quite short, but have more than 2k stars on Github. You can check this sheet at the start and end of your preparation.

17. Big collection of interview preparation links

It's an aggregator post on Reddit and it contains answers and tutorials for most commonly asked questions. You can find things like “How to Ace a Developer Phone Interview” or “My onsite interview experience at Google”. If you have no idea of what coding interview is like, this post is a great starting point for you.

Summary

Preparing coding interviews takes tons of work, but these websites can help you accomplish faster and easier.

But no one needs all 15 websites on this list.

I recommend you start by trying a handful of these websites at a time until you find the ones you have the most success with.

Article Updates

• Article Updated July 2021: Verified all links and confirmed recommendations are valid in 2021.
• Article Updated April 2019: Minor changes, an updated introduction section, and fixed typos. Interview prep words update for better searchability