Why Do Companies Use LeetCode for Interviews? The Truth Behind Algorithm Testing

Mar 12, 2026

The Problem

I spent months grinding LeetCode. Two problems a day. Weekends doing mock interviews. I got pretty good at it—I could solve most medium problems in under 20 minutes.

Then I started my first job as a software engineer. In three months, I never once needed to implement a binary search tree or detect a cycle in a linked list. My actual work? Writing API endpoints, debugging database queries, and figuring out why the deployment pipeline was broken.

So why did I spend all that time on algorithms I never use?

What I Found

I asked around. Read discussions. Talked to engineers at big companies. The answer isn’t what I expected.

It’s Not About Testing Real-World Skills

Companies know LeetCode doesn’t reflect day-to-day engineering. One Reddit commenter put it bluntly:

“Leetcode is a great resource for shaping your brain with algorithmic thinking, and it is almost absolutely necessary for JOB INTERVIEWS only.”

The interview process is disconnected from actual work. This frustrates everyone—candidates and interviewers alike. But the disconnect exists for a reason that makes sense from the company’s perspective.

The Filtering Problem

Big tech companies receive thousands of applications for every open position. Google reportedly gets over 3 million applications per year for about 20,000 roles. That’s 150 applicants per position.

Screening that many resumes is impossible manually. Traditional methods fail:

Resume screening → Unreliable, biased, easy to game
Take-home projects → Time-consuming, can be outsourced
Phone screens → Expensive, not scalable

LeetCode-style interviews solve the filtering problem:

Standardized → Every candidate gets same problems
Time-boxed → 45-60 minutes per round
Scalable → Can be administered remotely
Objective → Clear pass/fail criteria

The Signal Quality Question

Do algorithm problems actually predict job performance? The correlation is weaker than companies admit, but it’s not zero.

LeetCode tests show:

Fundamental CS knowledge: Do you understand data structures?
Problem decomposition: Can you break complex problems into steps?
Edge case thinking: Do you consider null inputs, overflow, duplicates?
Communication: Can you explain your approach?

These skills transfer to real work, even if the specific problems don’t. A developer who can reason about time complexity will write more efficient APIs. Someone who handles edge cases in interviews will handle edge cases in production.

Why This System Persists

Employer adoption drives candidate behavior. As one commenter noted:

“People grind leetcode because employers send tasks on leetcode.”

It’s a feedback loop:

Big companies adopt algorithm interviews
Candidates prepare using LeetCode
Companies see LeetCode practice correlates with interview success
More companies adopt the same format
More candidates use LeetCode

The system persists because changing it is risky. If your company drops algorithm interviews, how do you filter candidates? What’s the alternative that’s equally scalable and defensible?

The FAANG Effect

Not all companies require LeetCode. It’s most common at:

FAANG and similar tech giants → 90%+ require algorithm rounds
Well-funded startups → Often copy FAANG process
Non-tech companies → Varies widely
Smaller companies → Often skip it entirely

As one commenter pointed out:

“I don’t think I’ve ever met anyone with a leetcode account.”

This suggests LeetCode requirements cluster in certain industries and regions. If you’re not targeting FAANG, your experience may differ.

The Trade-offs

For Employers:

Benefit	Cost
Efficient filtering	Misses good candidates who can’t do algorithms
Standardized benchmark	Tests narrow skill set
Defensible process	Alienates experienced engineers
Remote-friendly	Creates false negatives

For Candidates:

Benefit	Cost
Clear preparation path	Time investment is massive
Skill development	Skills may not transfer to job
Equal opportunity	Experienced devs start from scratch
Industry standard	Feels like a gatekeeping ritual

Common Misconceptions

Myth 1: LeetCode Tests Real-World Skills

Reality: Most engineering work involves reading code, debugging, and system design—not implementing algorithms from scratch. Companies know this. They’re testing for something different: reasoning ability under pressure.

Myth 2: Good LeetCode Performance = Good Engineer

Reality: The correlation exists but isn’t perfect. I’ve met excellent engineers who struggle with algorithm interviews. I’ve also met people who ace LeetCode but write unmaintainable production code.

Myth 3: All Companies Require It

Reality: The LeetCode requirement clusters in specific sectors. Many companies use take-home projects, system design interviews, or pair programming exercises instead.

What This Means For You

If you’re job hunting, the strategy is straightforward:

Targeting FAANG? LeetCode is non-negotiable. Budget 2-3 months of practice minimum.

Targeting startups? Still useful, but also build projects and contribute to open source.

Not targeting tech? Focus on domain-specific skills and networking. LeetCode may be optional.

The current system isn’t fair. It overvalues a specific skill that doesn’t reflect daily work. But understanding why it exists helps you navigate it strategically rather than resentfully.

Summary

In this post, I explained why employers require LeetCode-style interviews. The key insight is that algorithm tests solve a filtering problem for companies with too many applicants, not a skill-assessment problem for identifying the best engineers. The system persists because it’s standardized, scalable, and defensible—not because it’s accurate.

Whether this system will change remains uncertain. Some companies experiment with alternatives like work-sample tests or pair programming interviews. But until a better alternative proves equally scalable, LeetCode remains the industry default for large tech employers.

Final Words + More Resources

My intention with this article was to help others share my knowledge and experience. If you want to contact me, you can contact by email: Email me

Here are also the most important links from this article along with some further resources that will help you in this scope:

👨‍💻 Reddit: Why is LeetCode basically required for job interviews?
👨‍💻 LeetCode Official Platform
👨‍💻 Cracking the Coding Interview

Oh, and if you found these resources useful, don’t forget to support me by starring the repo on GitHub!