HackerRank

Mid-sized

HackerRank is a technology company that provides a platform for technical skills assessment and coding interviews, helping companies evaluate and hire software developers. It is widely known for its coding challenges and competitive programming community used by both developers and recruiters.

5 interview notes · updated Aug 2026

HackerRank·Machine Learning Engineer·Online Assessment (OA)

Jun 2026

Took a 105-minute HackerRank OA for an ML Engineer role. Two questions: one algorithmic, one ML modeling task. Cleared 10 of 15 test cases on the coding problem and now sitting in that uncomfortable limbo of not knowing if that's enough to move forward.

Solve an algorithmic problem with 15 test cases (10 hidden) within the timed assessment.
Given a dataset, build a machine learning model that fits the problem.

“Got 10 out of 15, which means I missed all 5 hidden ones.”

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HackerRank·Software Engineer·Onsite - System Design / Architecture

Jun 2026

System design round at HackerRank for a software engineer role, centered entirely on designing a URL shortener. Pretty classic question but the depth they expected on trade-offs was more than I anticipated.

Design a URL shortening service like bit.ly or TinyURL. Walk through your requirements, capacity estimates, and overall architecture.
What data store would you choose for this system, and how would you handle sharding and caching?
How would you handle collision detection and ensure uniqueness in your encoding scheme?
How would you approach rate limiting and abuse prevention in this service?
How would you add analytics tracking to this system without impacting redirect latency?

“I started with functional requirements which felt safe: shorten a URL, redirect it, maybe support custom aliases and expiration.”

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HackerRank·Software Engineer·Executive / Final Round

Jun 2026

Spent over a month grinding through 7 sequential rounds at HackerRank only for the CEO to show up late to the final chat, give one-word answers, and end it after 10 minutes. The whole thing felt like a setup from the start.

What motivated you to start this company?

“I asked this to break the ice because the CEO was clearly not interested in being there.”

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HackerRank·Software Engineer·Onsite - Coding / Algorithms

Apr 2026

Coding round for a software engineer position at HackerRank. One algorithmic problem, graph traversal flavored, with a big constraint on k that rules out any brute force approach pretty quickly.

You have n friends labeled 1 to n. Each friend i always passes a ball to a fixed receiver[i]. Starting from friend 1, who holds the ball after exactly k passes? k can be up to around 10^9 so you can't just simulate it.

“The naive loop fails immediately once you see the constraint on k, which I did notice pretty fast.”

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HackerRank·Software Engineer·Onsite - System Design / Architecture

Apr 2026

System design round at HackerRank for a software engineer role, focused entirely on building an internal integration tool from scratch. Pretty thorough scope, covering everything from data modeling to frontend strategy, and they clearly wanted to see senior-level thinking on trade-offs.

Design an internal integration/tooling service end-to-end. Walk through requirement clarification, data modeling, backend architecture in Node.js, and frontend-backend collaboration.
How would you approach database design for this tool, including decisions around data volume, filtering needs, and indexing strategy?
When would you choose server-side rendering over client-side rendering for an internal tool, and how does that affect your full-stack data flow?

“This was basically the whole interview in one prompt.”

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