Software Alternatives, Accelerators & Startups

Project Euler VS PrivacyNotes

Compare Project Euler VS PrivacyNotes and see what are their differences

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Project Euler logo Project Euler

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

PrivacyNotes logo PrivacyNotes

Zero-knowledge encrypted notes, tasks, journals, files, and passwords in one app. Your keys never leave your device. One-time price, no subscription. Hosted in Switzerland.
Visit Website
  • Project Euler Landing page
    Landing page //
    2022-10-02
  • PrivacyNotes Journal
    Journal //
    2026-06-25
  • PrivacyNotes Settings
    Settings //
    2026-06-25
  • PrivacyNotes Website
    Website //
    2026-06-25

PrivacyNotes is a zero-knowledge encrypted workspace that brings your notes, tasks, journals, files, and passwords into one app, so you stop juggling four separate subscriptions.

Everything is encrypted on your device with XChaCha20-Poly1305 before it ever syncs. Your keys are derived from a recovery phrase that never touches our servers, so we cannot read your content, your filenames, or anything else. This is real zero-knowledge, not a marketing label.

Five pillars, one encrypted app:

  • Notes - a live markdown editor with note-to-note links, tags, and fast full-text search
  • Tasks - native checklists and task management next to your notes
  • Journals - daily entries with built-in mood, sleep, and medication tracking
  • Files - an encrypted vault for images, audio, and attachments
  • Vault - lock sensitive notes and logins behind a PIN or biometrics

Built for privacy, not surveillance:

  • No ads, no trackers, no analytics, ever
  • Sign in anonymously with a recovery phrase or with Google. No email or personal details required.
  • Open core: the encryption layer and database schema are published for independent review
  • Burn notes: self-destructing shares the server cannot read

Pricing that respects you:

  • Free covers every pillar with two-device sync and offline use
  • Pro is a one-time free, not a subscription, adding unlimited devices, note history, and more storage
  • Optional storage add-ons when you need them

Works on web, macOS, and soon iOS, Android, Windows and Linux with a responsive mobile layout. Import from Apple Notes, Standard Notes, Google Keep, Obsidian, and markdown in a few clicks.

Project Euler

Pricing URL
-
$ Details
Platforms
-
Release Date
-

PrivacyNotes

$ Details
freemium $48.0 / One-off (Early adopter price)
Platforms
MacOS Web Firefox Google Chrome Edge Safari
Release Date
2026 June
Startup details
Country
Switzerland
Employees
1 - 9

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.

PrivacyNotes features and specs

  • Privacy-focused
    PrivacyNotes is designed with privacy as a core principle, aiming to keep your notes secure and away from third-party access, which appeals to users concerned about data confidentiality.
  • Encryption
    The service typically emphasizes encryption to protect note content, meaning your data is scrambled and less vulnerable to unauthorized reading if intercepted or stored.
  • Ephemeral notes
    Many privacy note services offer self-destructing or temporary notes that automatically delete after being read or after a set time, reducing the digital footprint left behind.
  • Simple and lightweight
    Such tools often provide a clean, minimal interface focused on quick note creation and sharing without unnecessary features, making it easy to use.
  • No account required
    Privacy-oriented note apps frequently allow you to create and share notes without registration, lowering the barrier to entry and reducing personal data collection.

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 PrivacyNotes

Overall verdict

  • I don't have verified, specific information about PrivacyNotes (privacynotes.app) to make a reliable assessment of its quality, security practices, or features. I cannot confirm details about its encryption methods, privacy policy, company background, or user reviews.

Why this product is good

  • Unable to verify claims about encryption or zero-knowledge architecture without independent confirmation
  • No access to current user reviews, ratings, or reputation data for this specific service
  • Cannot confirm company legitimacy, ownership, or track record
  • Unable to verify uptime, reliability, or actual security audit results
  • No information available on pricing structure or terms of service specifics

Recommended for

  • Before using, research independently via security audit reports if available
  • Check for third-party security reviews or penetration testing results
  • Verify the company's privacy policy and data handling practices directly on their site
  • Look for user reviews on independent platforms rather than relying on marketing claims
  • Consider established, well-audited alternatives if handling highly sensitive information

Project Euler videos

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

More videos:

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

PrivacyNotes videos

No PrivacyNotes 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 PrivacyNotes)
Online Learning
100 100%
0% 0
Personal Notes
0 0%
100% 100
Online Education
100 100%
0% 0
Task Management
0 0%
100% 100

Questions & Answers

As answered by people managing Project Euler and PrivacyNotes.

Who are some of the biggest customers of your product?

PrivacyNotes's answer:

Honestly? We have no idea, and that is the entire point. Signup is anonymous (a recovery phrase or Google, no email or personal details), the app ships zero analytics and zero trackers, and zero-knowledge encryption means we cannot see who you are or what you store. We could not name a single customer if we tried. A privacy product that tracked its users closely enough to brag about them would be missing the plot.

What makes your product unique?

PrivacyNotes's answer:

PrivacyNotes is the only zero-knowledge encrypted workspace that keeps notes, tasks, journals, files, and a password vault behind one set of on-device keys. Most privacy apps do one of those well and rent it to you monthly. We do all five, encrypt everything with XChaCha20-Poly1305 before it leaves your device, and charge once instead of forever. The encryption core is open core, published so the claims can be verified rather than trusted.

Why should a person choose your product over its competitors?

PrivacyNotes's answer:

Three reasons:

  • One app, not four subscriptions. Standard Notes, Day One, and Lunatask each rent you a slice (notes, journaling, tasks). PrivacyNotes covers all of them plus files and a vault, for a fair one-time fee.
  • Real zero-knowledge. Your keys come from a recovery phrase that never touches our servers, so we cannot read your notes, your filenames, or your metadata. Some encrypted apps leave note or task metadata in the clear; we do not.
  • Verifiable, not just trusted. The crypto and schema are open core and published for review, and there is no ad, tracker, or analytics anywhere in the app.

How would you describe the primary audience of your product?

PrivacyNotes's answer:

Privacy-conscious individuals and independent professionals who handle information they would not want a vendor reading: lawyers, journalists, healthcare and mental-health practitioners, developers, security specialists, researchers, and founders. It also fits anyone who simply wants one private home for their notes, tasks, journaling, and wellness tracking instead of spreading them across surveillance-funded apps.

Which are the primary technologies used for building your product?

PrivacyNotes's answer:

React, TypeScript, Vite and Tailwind CSS.

What's the story behind your product?

PrivacyNotes's answer:

PrivacyNotes started from a simple frustration: staying organized meant scattering your life across half a dozen apps, most of which could read everything you typed and billed you monthly for the privilege. We wanted one place for notes, tasks, journals, files, and passwords, encrypted so thoroughly that the people running the servers could not read a word of it, and paid for once rather than forever. So we built the encryption first, made the keys live only on your device, and published the crypto as open core so the promise could be checked, not just believed. Everything else grew from one rule: your data is yours, and no one else's to mine.

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 PrivacyNotes

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...

PrivacyNotes Reviews

  1. FossFox
    Feature rich

    The best thing about this: No subscription model, it's a one-time fee for a lifetime license. But you can start for free with the generous freemium model. I only needed to upgrade to pro because I wanted to use the app on my phone, laptop and desktop. Highly recommended! Btw, it's a perfect markdown editor as well, not sure why they don't emphasize this more.

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 / about 2 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 / 5 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 / 7 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
View more

PrivacyNotes mentions (0)

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

What are some alternatives?

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

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

Standard Notes - A safe place for your notes, thoughts, and life's work

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

Apple Notes - Apple Notes functions as a service for making short text notes.

Codewars - Achieve code mastery through challenge.

Simplenote - The simplest way to keep notes. Light, clean, and free. Simplenote is now available for iOS, Android, Mac, and the web.