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HubSpot interview notes, page 2 of 3

Large Enterprises

Most of these HubSpot write-ups come from Software Engineers (26), then Product Managers (3) and Machine Learning Engineers (1). The most reported rounds are the system design round (13), the technical phone screen (7), the hiring manager screen (4) and the behavioral / leadership round (3).

30 interview notes · updated Jul 2026

HubSpot·Software Engineer·Onsite - Coding / Algorithms

May 2026
HubSpot coding round for a Software Engineer role. The whole thing revolved around a JSON parsing calculator problem that escalated across four parts, and I hit a wall on Part 3 that I still think about.
  • Given a JSON endpoint that returns a numeric value or a simple arithmetic operation (add, subtract, multiply, divide) on two numbers, write a program that fetches the data and computes the result. No nesting involved.
  • Extend the solution to handle nested arithmetic operations in the JSON, for example 1 plus the result of 1 plus 2 represented as nested JSON objects.
  • Deserialize the raw JSON string directly into a Java object with appropriate getters and setters, rather than manually extracting fields.
  • Further extend the calculator to support variable references (like x, y, z) that can be stored and looked up during evaluation.

“I knew Jackson going in but had only just picked it up, so there was definitely some nerves around whether I actually knew it well enough.”

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HubSpot·Software Engineer·Technical Phone Screen

May 2026
HubSpot technical phone screen for a software engineer role, one algorithmic problem the whole time. The question was a classic graph/search-adjacent puzzle dressed up with an API constraint, which made it trickier than it looked on the surface.
  • Given n people at a party, use a knows(a, b) API to find a 'celebrity': someone known by everyone else but who knows no one. Minimize the number of API calls, ideally to O(n). Return -1 if no such person exists.

“The O(n) part is what separates people who get it from people who brute-force it.”

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HubSpot·Software Engineer·Onsite - Behavioral / Leadership

May 2026
Had a behavioral round at HubSpot for a software engineering role and got hit with a pretty heavy AI safety question I wasn't expecting at all. Not a coding round, not system design, just a big open-ended scenario about responsible AI and launch tradeoffs. Left feeling like I probably underprepared for the ethics angle.
  • Tell me about a time you identified an AI safety risk in a product or project. How did you assess it, who did you bring in, what did you do to mitigate it, and what monitoring did you set up after launch? If you don't have a direct example, walk through how you'd handle harmful outputs like bias, jailbreaking, or privacy leakage when you're under deadline pressure and the business is pushing to ship.

“This one stopped me cold for a second.”

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HubSpot·Product Manager·Hiring Manager Screen

May 2026
Interviewed for a PM role at HubSpot and got asked about enterprise products I admire. Pretty short and conversational, not a deep case round.
  • Which enterprise product do you look up to and why?

“I blanked for a second and just named the first product that came to mind.”

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HubSpot·Software Engineer·Onsite - System Design / Architecture

May 2026
System design round at HubSpot for a software engineer role, focused entirely on designing a Netflix-scale video platform. Pretty deep scope covering upload pipelines, CDN strategy, search, and DRM. Left feeling like I covered the broad strokes but probably didn't go deep enough on a few areas.
  • Design a Netflix-like platform that supports video search, streaming, and uploads from both users and content studios.
  • Walk through the APIs you'd expose to clients and to content uploaders for this platform.
  • What does your data model look like, and what storage technologies would you choose for different parts of the system?
  • Describe the video upload and processing pipeline, from raw file ingestion to a video being available for streaming.
  • How would you design the CDN and caching strategy to support global low-latency streaming?
  • How would you handle reliability, fault tolerance, and scaling trade-offs across this system?
  • What would your monitoring, rate limiting, and abuse prevention strategy look like?

“The scope was massive and I think I spent too long on the upload pipeline before realizing I hadn't even touched search.”

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HubSpot·Software Engineer·Technical Phone Screen

Jun 2026
HubSpot software engineer interview that came down to a classic linked list merge problem. They wanted both iterative and recursive implementations, which I wasn't fully expecting, plus a complexity breakdown and edge case handling. Felt like a solid technical screen overall.
  • Given two sorted singly linked lists, merge them into a single sorted linked list. Implement both an iterative and a recursive solution, analyze the time and space complexity of each, and handle edge cases like empty lists and duplicate values.

“The iterative version came naturally enough.”

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HubSpot·Software Engineer·Onsite - System Design / Architecture

Jun 2026
HubSpot system design round for a software engineering role. One meaty question that took the whole session, and I left feeling like I'd covered maybe 70% of what they were looking for.
  • Design an algorithm to find duplicate files across a large directory tree. You're given an iterator of (path, size) pairs and a read_chunks function. Minimize I/O, handle hash collisions, support datasets too big to fit in memory, and explain how you'd parallelize it.

“I started with the obvious size-bucketing step and they seemed fine with that.”

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HubSpot·Software Engineer·Onsite - System Design / Architecture

Jun 2026
System design round at HubSpot for a senior backend/infrastructure role. The question was basically 'design Netflix/YouTube from scratch' and they wanted you to go deep on almost every layer of the stack. A lot of ground to cover in one session.
  • Design a large-scale video streaming platform like Netflix or YouTube, covering the full system from content ingestion through delivery to end users.
  • How would you design the video delivery path, including manifest generation, CDN distribution, and adaptive bitrate streaming?
  • How would you handle search and recommendations at scale for a video platform?
  • Walk through how you'd implement DRM and geo-restrictions for content licensing compliance.
  • How does your design handle hot content, like a viral video or a major live event with millions of concurrent viewers?

“This is one of those questions where you have to immediately triage what to go deep on versus skim, because you literally cannot cover everything well in 45 minutes.”

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HubSpot·Software Engineer·Hiring Manager Screen

Jun 2026
Interviewed for a marketing manager role at HubSpot. One behavioral question, pretty standard stuff, but it made me realize I hadn't thought carefully enough about how I actually talk through deadline pressure situations.
  • Can you describe a time you had to juggle several competing priorities under tight deadlines?

“I had a decent example ready but rambled a bit trying to cover too much context upfront.”

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HubSpot·Software Engineer·Onsite - System Design / Architecture

Jun 2026
HubSpot system design round for a software engineering role, and they came in with a pretty involved in-memory banking service problem that had way more moving parts than I expected for a single session.
  • Design an in-memory banking service supporting account creation, deposits, transfers, scheduled payments, a top-K accounts by total outgoing view, and account merging. Walk through data structures, method signatures, time/space complexities, and edge cases.

“This thing had six sub-operations and I kind of panicked when I saw the full list.”

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