
LeetCode
Codility
CodeSignal
iMocha
HackerEarth
Codewars
TestGorilla
HackerRank is a platform that allows companies to conduct interviews remotely to hire developers and for technical assessment purposes.

Anki
Instapaper
ChatPDF
AskYourPDF
Humata AI
Readwise
Omnivore
Read Papers & Chat with PDFs and Articles on Your Phone. Understand them. Remember them. Reedle brings web pages, PDF and formula rendering, AI chat with built-in spaced review into one reading experience, on any device.

Which is more popular?
Based on our record, HackerRank seems to be more popular. It has been mentioned 67 times since March 2021.
Website, pricing, platforms and company facts side by side.
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| Website | hackerrank.com | reedle.iopho.com |
| Pricing | — | |
| Platforms | — | |
| Company | — | Startup from the United Kingdom · 1 - 9 employees · 2026 |
| Listed in |
In their own words, as submitted to SaaSHub.


No description of HackerRank yet.
What if Pocket, Anki, and an AI tutor were one app? That's Reedle: a read-it-later app where AI chat and spaced repetition (FSRS) are built into reading, not added as an afterthought. Most reading apps are read-it-save apps. Reedle is a read-it-retain app. Save an article, highlight key passages,...
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
HackerRank is recommended for students, individual learners, and job seekers looking to improve their coding skills, as well as for companies seeking an efficient way to evaluate candidates' technical abilities during the hiring process.
Overall verdict
Why this product is good
Recommended for
Walkthroughs and reviews on video.
Is HackerRank A Good Idea?
More videos
Introducing Reedle: The AI Read-Later App That Helps You Understand and Remember
More videos
How often each product is chosen within a category, 0–100% relative to the other.


As answered by people managing HackerRank and Reedle.
Reedle's answer:
Reedle is built on a single premise that no other reading app has acted on: reading and remembering are one activity, not two. Every competing tool solves only half the problem. Save-it-later apps (Pocket, Omnivore, Instapaper) are excellent at capturing content but have no retention layer, so saved articles become a graveyard. Anki has rigorous spaced repetition but no reading experience, so users spend hours creating cards manually for content they read somewhere else. Readwise surfaces highlights after the fact but does not generate them from active reading. ChatPDF enables AI conversation but has no memory system, so each session starts from zero.
Reedle closes the loop. Save an article, read it with inline AI explanations, highlight the ideas that matter, and those highlights automatically become FSRS flashcards scheduled by the same algorithm that powers modern Anki. Nothing is extra. The reading creates the review material. The review points back to the original article context. The loop runs itself.
Three technical foundations make this coherent rather than gimmicky: full LaTeX and MathJax rendering for academic PDFs on mobile (the only read-it-later app to handle this correctly), context-aware AI chat that reasons about the specific passage you are reading rather than producing a generic document summary, and FSRS scheduling that calculates the optimal review interval for each individual idea so you spend less time reviewing and retain more.
Reedle's answer:
The case for Reedle depends on what you are currently using.
Versus Readwise Reader: Reedle has native FSRS spaced repetition rather than a passive highlight archive, costs less at every tier, renders LaTeX and MathJax correctly for academic papers, and supports YouTube and Bilibili video transcripts natively. Readwise is optimized for newsletter readers who want to resurface quotes. Reedle is built for people who read to learn and need the knowledge to stay.
Versus Anki: Anki requires double work, reading in one app and creating cards manually in another. Reedle automates the card creation step, preserves the full article context alongside each flashcard, and uses the same FSRS algorithm. Reviews are faster because you remember where each idea came from and can return to it in one tap.
Versus Pocket and Omnivore: Both are read-it-save apps with no memory layer. Pocket shut down in July 2025. Reedle is the natural migration path that also solves the retention problem neither app ever addressed.
Versus ChatPDF: ChatPDF is a single-session document tool. Reedle builds a persistent library across all your reading, with cross-document semantic search, reading streak tracking, and long-term FSRS review scheduling.
The short version: Reedle replaces a three-app stack (read-it-later plus AI chat plus spaced repetition) with a single coherent workflow that costs less and works better than any of the parts in isolation.
Reedle's answer:
Reedle is built for people who read with intent, not for entertainment. Three groups form the core audience.
Researchers, PhD students, and academics who need to process large volumes of papers and retain methodology, findings, and citations across months of work. For this group, Reedle's LaTeX rendering, Zotero library integration, and FSRS review system replace a fragmented stack of PDF readers, reference managers, and manual Anki decks.
Lifelong learners and knowledge workers who maintain a serious non-fiction reading habit and have experienced the frustration of finishing a book or article and retaining almost nothing. These users come from Pocket, Omnivore, Readwise, or Instapaper and are specifically looking for a tool that closes the gap between saving and remembering.
Language learners who use reading in their target language as a primary acquisition method. Reedle's contextual translation, grammar analysis, and spaced review of new vocabulary within real articles gives this group a workflow that traditional flashcard apps cannot replicate.
What unites all three groups is a belief that reading time is an investment, and that an investment should compound. Reedle is for readers who refuse to accept that hours of reading evaporate within weeks.
Reedle's answer:
Reedle started with an observation that felt almost embarrassing to admit: people who consider themselves serious readers retain almost nothing of what they read. Not because they are careless, but because every tool in the reading stack is optimized for the wrong thing. Browser bookmarks, read-it-later apps, and even e-readers are all built around the act of saving, not the act of learning.
The cognitive science on this has been clear for decades. Passive reading without retrieval practice produces very little long-term retention. Active recall, spaced over time, is dramatically more effective. Anki proved this could be turned into software. But Anki and reading lived in completely separate workflows, and the manual work of creating cards from reading material was enough friction to stop most people from ever making the connection.
Reedle was built by the iopho team in London to answer a simple question: what if the reading experience itself generated the review material? What if saving a highlight was enough, and the algorithm handled everything else? The result is an app that treats reading and remembering as a single continuous activity rather than two separate disciplines that most people never successfully combine.
Reedle's answer:
Reedle is a direct-to-consumer product used by individual readers rather than enterprise teams. Our early users are students and laboratories from Imperial College London, the University of Cambridge, the University of Manchester, the University of Edinburgh, Carnegie Mellon University, and Cornell University.
The most engaged users are doctoral and postdoctoral researchers who process 10 to 30 academic papers per week and use FSRS review to maintain working knowledge across long research cycles. The second largest group is self-directed learners in technical fields, particularly software engineers and data scientists who read to keep up with a fast-moving field. A third significant cohort is language learners at the B2 to C1 level who use real-world reading as their primary input method and rely on Reedle's contextual translation and vocabulary review features.
Reedle's answer:
Reedle is built around a small number of purpose-chosen technologies, each chosen because it solves a specific problem that cheaper or simpler alternatives could not.
FSRS (Free Spaced Repetition Scheduler): The memory algorithm at Reedle's core is the same one powering the latest versions of Anki, backed by decades of cognitive science research on optimal review intervals. Rather than fixed daily reminders, FSRS tracks how well you remember each individual idea and schedules the next review at the exact moment that reinforces long-term memory with the least amount of your time.
Offline-first architecture: Your entire library, reading progress, and review queue are available without an internet connection. Articles you have opened are cached locally, highlights sync the moment you reconnect, and nothing is lost if you read on a plane, underground, or anywhere with unreliable signal. The same experience runs on iOS, Android, and any modern web browser.
Academic document rendering: Reedle processes PDFs at the structural level rather than treating them as flat images. Mathematical formulas, LaTeX notation, and MathJax expressions render correctly on a phone screen. Dense research papers reflow to fit your display without the pinch-to-zoom experience that makes mobile PDF reading painful everywhere else.
Contextual AI, not generic AI: The AI in Reedle is connected to the specific text you are reading at that moment. When you ask a question, the answer is grounded in the actual passage, not a generic response generated from training data alone. The same AI layer powers summaries, translation, and the weekly digest, all running against your personal library rather than the open web.
All data is stored on EU-based servers and never used to train external models.
Share your experience with using HackerRank and Reedle. For example, how are they different and which one is better?
External articles and on-site reviews we used to compare the two products.


What are LeetCode and LeetCode alternatives good for?LeetCode💡Interested in leveling up your career? Apply to the Formation Fellowship...
HackerRank’s challenges cover a wide range of topics and difficulty levels, allowing developers to enhance their problem-solving skills and learn new algorithms and data structures. The competitive nature of...
HackerRank offers a wide array of challenges across various domains such as algorithms, mathematics, SQL, and functional programming. Its interface is user-friendly, and the platform provides detailed feedback on...
What I like the most is its high-quality AI-generated questions for improving and verifying your understanding, along with the integration with Anki / FSRS. You can easily review the key points of articles and jump...
Reedle perfectly solves my pain point of "collecting but never reading, reading but never remembering." It integrates knowledge acquisition, comprehension, and long-term memory into an incredibly elegant workflow. If...
Recommendations tracked on public social media and blogs since March 2021.


This way, you transfer what you already know (problem-solving) but only change the syntax. Platforms like Hackerrank are also great to solve the same problem in different languages and learn from other people’s solutions. - Source: dev.to / about 1 year ago
Firstly, solve some common data structure problems with it. Implement some data structures like arrays, linked lists, stacks, queues, etc. You can check common problems on LeetCode, Hackerank or some other resources. - Source: dev.to / over 2 years ago
I don't have a consecutive internet connection and I can't keep up learning process so I started practicing in hackerrank.com I have started some challenges in python and c++ there. Thus I have no internet connection so I cannot practice... Source: almost 3 years ago
Tracking Reedle since Mar 2026.
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