
LeetCode
Exercism
Codewars
HackerRank
CodeSignal
CodinGame
CodeCombat
Project Euler is a series of challenging mathematical/computer programming problems that will...

Codility
CodeInterview.io
HackerRank Interview
Coderbyte
coderpad
CodeSignal
CodeSubmit
CodeSession puts you and your candidate in a shared IDE and whiteboard to see how they actually think and work, not whether they can crack a coding puzzle. Free forever plan, with session packs and subscriptions that scale as you grow.

Which is more popular?
Based on our record, Project Euler seems to be more popular. It has been mentioned 415 times since March 2021.
Website, pricing, platforms and company facts side by side.
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| Website | projecteuler.net | codesession.io |
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| Company | — | Startup from the United States · 1 - 9 employees |
| Listed in |
In their own words, as submitted to SaaSHub.


No description of Project Euler yet.
CodeSession is a collaborative technical interview platform built around a simple idea: the best way to evaluate a software engineer is to work with them, not watch them solve a puzzle. Most technical interview tools are built around algorithm question banks and timed coding challenges that test...
What each product offers, as listed by its team.


Possible disadvantages
An editorial look at what each product does well and who it suits.


Overall verdict
Why this product is good
Recommended for
Overall verdict
Why this product is good
Recommended for
Walkthroughs and reviews on video.
Project Euler Challenges 1–4 - Coding Challenges with Florin
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How often each product is chosen within a category, 0–100% relative to the other.


As answered by people managing Project Euler and CodeSession.
CodeSession's answer:
Technical hiring has become exhausting for everyone involved. Hiring teams design increasingly complex challenges, candidates burn hours completing them, and at the end of it nobody has a better feel for whether this person would actually thrive on the team. CodeSession takes a different approach entirely. Rather than testing whether someone can produce plausible-looking code in isolation, it puts you in a shared IDE and whiteboard with your candidate so you can experience how they actually work. Do they ask good clarifying questions? Can they start from nothing, build iteratively, and take you on that journey? How do they think and communicate under realistic conditions? Those are the things that predict job performance, and they're exactly what a collaborative CodeSession reveals. It does one thing and does it really well. And unlike most tools in this space, pricing is based on interview volume rather than seat count. Your whole team participates, and you only pay for what you actually use.
CodeSession's answer:
Most tools on the market are still optimizing for the wrong thing: screening whether someone can write reasonable-looking code in isolation, which tells you very little about what it's actually like to work with them. CodeSession is built around a different question: how does this person think, communicate, and solve problems when working alongside someone else? That's the signal that matters, and it's the one that collaborative interviews reliably surface. There's also no home-grown setup to maintain. No screen-sharing privacy concerns, no elaborate candidate instructions, no cobbling together a Google Doc and a whiteboard link and a video call. You send one link and everything is ready to go. Most teams are running their first interview within 15 minutes of signing up. Pricing is straightforward and flexible as well. Session packs for teams with occasional hiring needs, subscriptions for ongoing volume, and a genuine free forever plan to get started with no credit card required.
CodeSession's answer:
The primary audience is engineering hiring teams - startup founders conducting their first technical hires, engineering managers building out a team, and technical recruiters running multiple interview loops in parallel. What they share is a belief that the best hiring signal comes from working with a candidate rather than watching them perform, and a frustration with tools that are either built around algorithm puzzle banks or require elaborate setup to get off the ground. CodeSession fits teams at any hiring volume thanks to a genuine free forever plan, one-time session packs for a hiring sprint or a single open role, and subscriptions that scale with ongoing demand. So whether you hire two engineers a year or run dozens of interviews a month, there's a pricing model that fits without overcharging you for capacity you're not using.
CodeSession's answer:
CodeSession was built to solve a problem its founder, David Haney, encountered firsthand while running technical interviews at Stack Overflow, where he worked as an engineering leader for nearly a decade. Stack's interview philosophy deliberately avoided LeetCode-style algorithm questions. The team believed they didn't reliably predict whether someone could do the actual job. Instead, they preferred collaborative, peer-programming style interviews where candidates worked through realistic problems alongside an interviewer. The trouble was the tooling. Stack was using Google Docs with a monospace font as a makeshift coding environment, which meant no auto-indentation, no syntax highlighting, and a word processor constantly trying to autocorrect code into prose.
David looked at what the market offered and found that every tool was either expensive, built around algorithm question banks, or both, but none of them fit Stack's collaborative interview style. So in 2020, on his own time and personal hardware, he started building what would eventually become CodeSession. Stack Overflow became its first real user and a proving ground for the product's core ideas. After iterating based on feedback from Stack's engineering team, David opened CodeSession to the public in 2022 and has continued to iterate on and improve it since.
Share your experience with using Project Euler and CodeSession. For example, how are they different and which one is better?
External articles and on-site reviews we used to compare the two products.


Project Euler provides a large collection of challenges in the domain of computer science and mathematics. The challenges typically involve writing a small program to figure out the solution to a clever mathematical...
If you are studying algorithms and computer programming, chances are you’ve heard of Project Euler. A collection of mathematical problems made for problem solvers who are interested to combine mathematics and...
We have no reviews of CodeSession yet. Be the first one to post
Recommendations tracked on public social media and blogs since March 2021.


Let's hope this is going to help me solve some more Project Euler [1] problems! [1] https://projecteuler.net/. - Source: Hacker News / 5 months ago
Https://projecteuler.net/ for "Thinker" brain food. (it still has the issue of not being a pragmatic use of time, but there are plenty interesting enough questions which it at least helps). - Source: Hacker News / 8 months ago
I have a Project Euler (https://projecteuler.net/) account. Though I do not register at all on the leader board I will sometimes work obsessively on a problem just to make one of the level icons light up for me. There is not really... - Source: Hacker News / 10 months ago
Tracking CodeSession since Jun 2026.
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