Kinnu app review: is it worth it?

By the edgi team Facts checked September 30, 2026

Kinnu is a good free app if you like to learn by reading: 100 public pathways of chapter-length lessons, on subjects from Norse Mythology to Macroeconomics, with no ads and questions on most lessons. It's a weaker fit if you want lessons you finish in a minute or two, or a list of sources behind what you read: a public Kinnu lesson runs about 1,500 words, and none of the 899 names its author or ends with a list of sources.

We make edgi, a learning app that competes with Kinnu, so weigh this accordingly.

What we looked at: we counted all 899 of Kinnu's public lessons and read three pathways closely (September 2026). We also read its App Store listing with its screenshots and version notes, all 164 written reviews on the US store, Kinnu's website and blog, and its pricing. We did not make an account, open the app or use the paid products, so anything below about the inside of the app is in Kinnu's words, its screenshots or its reviewers'.

What's in Kinnu

Kinnu's free app is called General Knowledge (exam prep is a separate, paid app, covered below). It's built from pathways: a subject broken into a run of lessons you take in order. Kinnu publishes 100 of them on its website, in seven categories, with 4 to 12 lessons each (median 9) and 899 lessons in all.

Counted from the public pages on kinnu.xyz, September 2026. The app holds more than the site: three of the 32 "Popular courses" on its App Store listing have no public pathway under that name, Fungi and Chemistry among them, so treat the table as a floor.

The lesson. A public lesson reads like a short chapter: about 1,500 words (the median), split into about ten cards of about 150 words each. Most lessons (69%) give every card its own subheading, like "Stage 2: Light Sleep and the Role of Sleep Spindles". The rest read as flowing narrative, and those are the illustrated ones: 88% carry an image, against 27% of the headed kind. Questions sit at the bottom; on the web you tap one to see its answer.

Memory Shield. Kinnu's App Store listing says "Never forget what you've learned with our Memory Shield technology" and promises "Interactive, adaptive questions and games to refresh and retain your knowledge." Its Kinnu 2.0 post (August 2024) says more. Memory Shields are "dynamic aids to help you learn, remember and master Orbs" (the Orb is Kinnu's base unit of knowledge), and "Different shields help you learn different things": "Ordering Shields help build mental timelines for chronological knowledge". The one question in the App Store screenshots sits under a Memory Shield label and offers a choice of two answers. We haven't used it.

The Knowledge Bank. The listing says "Track your progress and watch your mind grow with the Knowledge Bank." The 2.0 post says it shows which Orbs are "safe in your memory" and which are "at risk of being forgotten", with a "Strengthen" button for the second kind. The same post says Kinnu 2.0 "does away with streaks (kind of)" in favor of Crane Stamps: each day you complete a learning session, you get a stamp on your learning calendar.

Audio. The listing promises an "Audio version of all content to learn on the go." None of the 899 public pages carries audio, so we haven't heard it. An App Store reviewer: "Kinnu has a feature that reads the material to you which makes it a whole lot easier for me to follow along" (December 2023).

Certificates. Sold in the app at $7.99, $14.99 and $19.99. We found nothing on Kinnu's listings or website that says what one certifies.

What Kinnu does well

It's free and it has no ads. The General Knowledge app costs nothing, and none of the 164 written US App Store reviews says it shows ads. That is also what reviewers praise most. We sorted the written reviews by hand, by what they say. A review can make more than one point, and the counts are close rather than exact.

One App Store reviewer: "No ads. Free learning. What else do you need?" (September 2023). As of September 2026 the app is rated 4.8 from 506 US App Store ratings, and Google Play shows 4.4 from 7.16K reviews.

The best pathways are well written. Cognitive Biases (10 lessons, about 15,000 words) opens at the Monte Carlo casino on 18 August 1913, where the wheel landed on black 26 times before red came up, and builds from there. It names researchers and dates, and it uses real cases, from a study of judges and dice in sentencing to Iceland's 2021 vaccination figures. Its base-rate example takes a test that is 95 percent accurate for a condition 0.5 percent of people have, and shows that a positive result means an 8.7 percent chance you're ill. We checked the arithmetic. It's right.

Norse Mythology is as good in a different voice. It names the old texts it draws on (the Poetic Edda, the Prose Edda, Sturluson), says plainly where they run out ("none of this is described in much detail by Old Norse sources"), and points out that the sources don't describe dwarves as short. Its 44 questions across nine lessons, the most of any pathway we read, reach for the stories:

• "How did the gods convince Fenrir to put on his magical chains?" Answer shown: "They told him it was a test of his strength"
• "What substance did Loki discover to be Baldur's weakness?" Answer shown: "Mistletoe"

If you install it, the pathways that look most finished on the public site, featured by Kinnu and with images and questions on nearly every lesson, include Artificial Intelligence, Superpower Learning, Positive Psychology, The History of Ancient Rome, Macroeconomics and Norse Mythology.

You can read all of it before you install. Every lesson is on kinnu.xyz without an account, so you can judge the writing first. The pictures are credited too: 404 lessons carry at least one image credited to Wikimedia Commons or Wikipedia, with its license in the caption.

Most public lessons, 755 of 899, come with questions. An App Store reviewer: "I love the format of being quizzed as i read. helps retain so much." (December 2024)

Kinnu also explains itself in public. It has published its research, including an August 2024 post on learning experiments with 10,000 volunteers, and the reasoning behind Kinnu 2.0. The efficiency claims in those posts are Kinnu's own; we haven't checked them.

Where it's weaker

The lessons are longer than "bite-sized" suggests. Kinnu's listing calls its content "Bite-sized". A card fits that, at about 150 words; a lesson is about ten cards, around 1,500 words or six minutes of reading at 250 words a minute. The "5 min a day" in Kinnu's App Store screenshots is a daily target, and we can't see how the app splits a lesson into sessions.

The questions on the public pages are brief and mostly recall. 144 lessons have none. Where there are questions, the median is two per lesson and the median answer is three words. We sorted all 2,071 question stems by their first words: about nine in ten ask you to name something ("What is", "Who", "What term"), and about one in ten asks why or how. A typical one: "What is the term for a disruption to natural sleep-wake cycles caused by shifts in time zone?" The answer shown is "Jet lag".

The app's questions may work differently. Kinnu calls them "interactive, adaptive", and we haven't seen them. Many reviewers like them (31 written reviews praise the quizzes or how the app helps things stick), while five, spread from 2024 to 2026, say they repeat or test names more than understanding. One four-star reviewer said they "seem to be focused on unimportant facts or just the names of things I have learned" (August 2026).

Quality is uneven across the library. 38 of the 100 public pathways have no image in any lesson, Greek Mythology among them. The writing varies too. Science of Sleep, one of Kinnu's featured courses, is a clean overview that names no study or researcher in about 13,000 words. "Research suggests" and "studies have shown" do the work, so you come away with the advice but not the evidence behind it.

None of the 899 lessons says who wrote it or when, or ends with a list of sources, and across all 899 we found no links out to sources beyond the image credits. Four written reviews ask for sources; one App Store reviewer noted that "there are no sources cited or authors of lessons credited" (August 2026).

We found no web version of the app. Kinnu runs on iPhone (iOS 17 or later) and Android. On the web you can read the General Knowledge lessons and tap to reveal each question's answer, but we found no in-browser version of the app itself.

Bug reports are mostly in the past. Thirteen written reviews mention bugs, crashes or failed logins; eight date from August 2024 to January 2025, around the 2.0 release, and four from 2026.

What Kinnu costs

As of September 2026, from Kinnu's US App Store listings and its website:

Nothing we can read says what the $1.99 "Monthly" item unlocks, so we won't guess.

Kinnu's exam-prep app

Kinnu now makes two products. Its homepage lists Exam Prep first (SQE, SAT, CFA and BCBA) and General Knowledge second. Kinnu's own timeline shows law prep for the SQE on mobile in May 2025 and on the web in October 2025, CFA prep in February 2026 and SAT prep in July 2026. Exam Prep is a separate App Store app, first released on 22 December 2025, with monthly plans from $19 to $65 after a 7-day trial. All four of Kinnu's 2026 blog posts so far are about the CFA.

Kinnu keeps updating the General Knowledge app. The latest version came out on 2 September 2026, and the 14 August 2026 release added crane stamp tracking on the map, a weekly stamp widget and a way to ignore a question with one tap. The General Knowledge app is still free.

We haven't used the exam-prep app. It's a sensible business, since people pay to pass tests, and it sits apart from the free app this review is about.

Where edgi fits

edgi is a free app for iPhone and the web (no Android app), built from 60-second Lessons and short videos; each idea you finish becomes a card on a Map that shows what it connects to. edgi has no review schedule, only a streak. If you want an app built to "refresh and retain your knowledge", in Kinnu's words, pick Kinnu. More in edgi vs Kinnu.

Kinnu's Cognitive Biases pathway teaches confirmation bias with Wason's 2-4-6 task. Here is edgi's 60-second take on the same idea.

Confirmation Bias Confirmation bias leads people to seek, interpret, and remember evidence that fits their prior beliefs while ignoring contrary facts.

60-second Lesson

Confirmation Bias

We test our beliefs with evidence that can only agree, then count every yes as proof.

Play it here Read about confirmation bias

FAQ

Is Kinnu free? The General Knowledge app is free to download and use, with no ads. It sells optional certificates ($7.99 to $19.99) and an item called "Monthly" at $1.99 that we found no explanation of. Exam prep is a separate paid app.

Is Kinnu worth it? Yes, if you like learning by reading. It's free with no ads, and its best pathways, Cognitive Biases and Norse Mythology among them, are well written. If you want lessons you finish in a minute or two, or a list of sources behind each lesson, it isn't built for that.

How long is a Kinnu lesson? A public lesson is about 1,500 words (the median of all 899, counted September 2026), roughly six minutes of reading. Kinnu's "5 min a day" is a daily target, and we haven't seen how the app splits a lesson into sessions.

What is Memory Shield? A Kinnu feature. Its App Store listing says "Never forget what you've learned with our Memory Shield technology" and describes "Interactive, adaptive questions and games to refresh and retain your knowledge." Kinnu's 2.0 post (August 2024) calls Memory Shields "dynamic aids to help you learn, remember and master Orbs", with different shields for different things; Ordering Shields, for example, help build timelines. We haven't used it.

Does Kinnu work on Android or the web? Android, yes, on Google Play. On the web you can read the General Knowledge lessons at kinnu.xyz without an account, but we found no in-browser version of the app itself. The exam-prep products do run on the web.

Is Kinnu good for exam prep? The General Knowledge app isn't built for exams. Kinnu sells prep for the SQE, SAT, CFA and BCBA in a separate App Store app, at $19 to $65 a month after a 7-day trial. We haven't used it.

Is edgi free? Yes. Lessons, cards and the Map are free. A few Sets are open from the start, and the rest unlock with coins you earn by learning. An optional Pro subscription opens two Sets a day without coins, raises the limits on making your own Lessons and adds offline access.