Software Alternatives, Accelerators & Startups

Project Euler VS CodeSession

Compare Project Euler VS CodeSession and see what are their differences

Project Euler logo Project Euler

Project Euler is a series of challenging mathematical/computer programming problems that will...

CodeSession logo CodeSession

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.
  • Project Euler Landing page
    Landing page //
    2022-10-02
  • CodeSession Simple, effective code interviews
    Simple, effective code interviews //
    2026-06-23
  • CodeSession Interview devs the way they work - together.
    Interview devs the way they work - together. //
    2026-06-23
  • CodeSession Everything you need. Nothing you don't.
    Everything you need. Nothing you don't. //
    2026-06-23

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 whether someone has memorized the right solutions. But the ability to produce plausible-looking code in isolation tells you very little about what it's actually like to work with someone. What matters is how they think, how they communicate, how they break down an unfamiliar problem, and whether they can build something from nothing while taking you along for the ride.

CodeSession puts you and your candidate in a shared, real-time IDE and whiteboard so you can find out. Both parties can type simultaneously in a full-featured coding environment with syntax highlighting, auto-formatting, and support for 40+ programming languages. An embedded whiteboard handles system design and architecture discussions without switching tools. Take-home test mode supports asynchronous evaluation when live interviews aren't practical. Every session is stored permanently at a unique link so your team can review and debrief at any time.

There's nothing for candidates to install and no account required. They click a link and they're in. Most hiring teams are running their first interview within 15 minutes of signing up.

Pricing is designed to fit any hiring volume. A free forever plan covers two interviews per month with no credit card required. One-time session packs are available for teams with seasonal or occasional hiring needs. Monthly and annual subscriptions scale from early-stage startups to high-volume recruiting teams. All plans include unlimited users, so your entire team can participate without adding cost.

CodeSession was built by a former engineering leader at Stack Overflow who couldn't find a tool that supported collaborative, conversational interviews, so he built one.

Project Euler features and specs

  • Problem-Solving Skills
    Project Euler offers a range of problems that can help enhance your mathematical and algorithmic problem-solving abilities.
  • Programming Practice
    It provides an excellent platform to practice and improve your programming skills across multiple languages.
  • Mathematical Insight
    Many problems require a deep understanding of mathematical concepts, thus helping users to gain and apply advanced mathematical knowledge.
  • Community
    Project Euler has a vibrant community where you can discuss problems and solutions with like-minded individuals.
  • Free Access
    All the problems and resources on Project Euler are freely accessible, making it an affordable way to learn.
  • Self-Paced Learning
    Users can progress at their own pace, making it suitable for learners of all levels.

Possible disadvantages of Project Euler

  • Steep Learning Curve
    The problems can become very challenging quickly, which might be discouraging for beginners.
  • Limited Step-by-Step Guidance
    There is little to no step-by-step guidance or hints available, which might hinder the learning process for some users.
  • Focus on Mathematics
    The heavy focus on mathematical problems may not appeal to those primarily interested in practical programming tasks.
  • Lack of Immediate Feedback
    The platform does not offer immediate feedback on code submissions, which might slow down the learning process.
  • No Built-in IDE
    Users need to use their own development environments, which might be inconvenient for some, especially beginners.

CodeSession features and specs

  • Real-Time Collaborative Coding
    Work through problems with candidates side by side in a shared IDE, the same way your team actually writes code every day.
  • Instant Candidate Access
    Candidates click a link and they're in. Nothing to install, no account to create, no setup instructions to send.
  • Embedded Whiteboard
    Sketch out system designs and architecture without leaving the interview environment or sending candidates to a second link.
  • Custom Templates
    Set up a consistent starting point for every interview so candidates begin from the same baseline and your process stays repeatable.
  • Up and Running in 15 Minutes
    No implementation project, no IT involvement. Sign up, configure a session, and send a link. Most teams conduct their first interview the same day they sign up.

Analysis of Project Euler

Overall verdict

  • Yes, Project Euler is considered a beneficial tool for those interested in improving their problem-solving abilities and programming skills. It offers a wide variety of problems that range in difficulty and provide valuable insights into the application of mathematical and computational concepts.

Why this product is good

  • Project Euler is a website dedicated to a series of challenging mathematical and computational problems. It is aimed at people interested in learning more about computer science, mathematics, algorithm design, and programming. The problems encourage you to think deeply about efficient algorithms and solutions. It also fosters the development of problem-solving skills and the enhancement of coding skills.

Recommended for

  • Individuals interested in competitive programming
  • Students studying computer science or mathematics
  • Professionals seeking to improve their algorithmic thinking
  • Anyone interested in challenging themselves with mathematical problems
  • Educators looking for challenging problems to test their students

Analysis of CodeSession

Overall verdict

  • I don't have verified information about CodeSession (codesession.io) in my knowledge base, so I can't confirm its features, quality, or reputation with confidence. I'd recommend researching current reviews, checking their official website, and looking for user feedback on platforms like G2, Trustpilot, or Reddit before making a decision.

Why this product is good

  • Unable to verify specific features or capabilities of this product
  • No confirmed user reviews or ratings available in my training data
  • Cannot confirm company legitimacy, pricing, or service quality
  • May be a newer or niche product not widely covered in available information

Recommended for

  • Users should independently verify this product through official sources
  • Check recent user reviews on trusted review platforms
  • Look for case studies or testimonials from actual users
  • Contact the company directly for a demo or trial before committing

Project Euler videos

Project Euler Challenges 1โ€“4 - Coding Challenges with Florin

More videos:

  • Review - Project Euler Challenges 5โ€“12 - Coding Challenges with Florin

CodeSession videos

No CodeSession videos yet. You could help us improve this page by suggesting one.

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Category Popularity

0-100% (relative to Project Euler and CodeSession)
Online Learning
100 100%
0% 0
Candidate Screening And Assessment
Online Education
100 100%
0% 0
Recruitment
0 0%
100% 100

Questions & Answers

As answered by people managing Project Euler and CodeSession.

What makes your product unique?

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.

Why should a person choose your product over its competitors?

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.

How would you describe the primary audience of your product?

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.

What's the story behind your product?

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.

User comments

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Reviews

These are some of the external sources and on-site user reviews we've used to compare Project Euler and CodeSession

Project Euler Reviews

The 10 Most Popular Coding Challenge Websites [Updated for 2021]
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 formula or equation, such as finding the sum of digits of all numbers preceding each number in a series.
Top 25 websites for coding challenge and competition [Updated for 2021]
If you are studying algorithms and computer programming, chances are youโ€™ve heard of Project Euler. A collection of mathematical problems made for problem solvers who are interested to combine mathematics and programming, Project Euler requires the use of mathematics to form algorithms and arrive at efficient solutions, and computer programming to actually solve it. These...

CodeSession Reviews

We have no reviews of CodeSession yet.
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Social recommendations and mentions

Based on our record, Project Euler seems to be more popular. It has been mentiond 415 times since March 2021. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.

Project Euler mentions (415)

  • Fast Factorial Algorithms
    Let's hope this is going to help me solve some more Project Euler [1] problems! [1] https://projecteuler.net/. - Source: Hacker News / 3 months ago
  • I Miss Thinking Hard
    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 / 7 months ago
  • A simple leaderboard changed player behavior in my puzzle game
    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 competition just a tiny reward. - Source: Hacker News / 8 months ago
  • Does hobby programming indicate that you would rather invent than discover?
    I do hobby programing. It is sometimes to create something (supposedly) useful. Lately though it is more discovery and a little math like. I enjoy Project Euler (https://projecteuler.net/. Recently I have been playing with superpermutations (https://projecteuler.net/) and pencil and paper is useful but filling lots of paper with lots of numbers is not that fun. - Source: Hacker News / over 1 year ago
  • Solving 100 Project Euler problems using 100 languages
    As pointed out in a sibling comment, it appears that quote only shows up if you're logged in, but assuming you have an account and are logged in, it's on the homepage (https://projecteuler.net/), second paragraph under the following heading: > I learned so much solving problem XXX, so is it okay to publish my solution elsewhere? > It appears that you have answered your own question. There is nothing quite like... - Source: Hacker News / over 1 year ago
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CodeSession mentions (0)

We have not tracked any mentions of CodeSession yet. Tracking of CodeSession recommendations started around Jun 2026.

What are some alternatives?

When comparing Project Euler and CodeSession, you can also consider the following products

LeetCode - Practice and level up your development skills and prepare for technical interviews.

Codility - Codility provides a SaaS platform with advanced validation, security and protection features to evaluate the skills of software engineers.

Exercism - Download and solve practice problems in over 30 different languages.

CodeInterview.io - CodeInterview is a live coding interview tool for developers.

Codewars - Achieve code mastery through challenge.

HackerRank Interview - An all-in-one solution for remote technical interviewing.