Comparison

Pengword vs Kusari

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Pengword

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Key Features of Pengword ■ AI-Powered Input Assistance Simply enter a word, and the AI automatically generates its meaning, part of speech, phonetic symbols, example sentences, synonyms, and antonyms. Audio playback for both words and example sentences is also available. Currently, the app supports the following four languages: - English, Swedish, Spanish, French and Italian The following premium features are available to subscribers: - Customizable Example Sentences: Specify the length and tone of generated sentences. ■ Spaced Repetition Learning The app prompts you to review registered words just as your brain is about to forget them, based on the forgetting curve. To improve retention, Pengword offers multimodal review methods, including: - Multiple-choice quizzes - Keyboard input - Fill-in-the-blank sentences - Listening exercises ■ Grow Your Penguin as You Review This feature is a personal passion project of the developer! As you review words, your penguin egg will hatch and grow. You can view your collection of grown penguins in the Gallery. This adds a touch of fun to the often-monotonous task of memorization. -------------------------------------------------------------------------- "Scout Mode": Discover New Words While Pengword's primary focus is registering words you want to learn, Scout Mode is designed for those times you want to encounter something new. In Scout Mode, the AI suggests words based on your selected learning goals and level (e.g., Goal: "TOEIC," Level: "600–750"). You can sort through these suggestions by swiping left or right to indicate whether you already know the word. Words you didn't know can be registered in bulk, with the AI instantly generating all definitions and example sentences for you. -------------------------------------------------------------------------- Recommended For: - Those looking to expand their vocabulary efficiently. - Anyone who wants to save time on manual flashcard creation. - Learners who want to review words at the scientifically optimal time. - Penguin lovers! [Terms of Service] https://pengword-a053b.web.app/terms [Privacy Policy] https://pengword-a053b.web.app/privacy_policy

About

Kusari

This app uses behavioral economics to build a daily English learning habit. It employs a commitment device where users risk losing money if they miss their daily tasks, encouraging consistent practice through financial stakes rather than willpower. Daily activities include reading, shadowing, and AI conversation, taking 15-20 minutes.

Highlights
  • Commitment device with financial stakes
  • Daily reading, shadowing, and AI conversation
  • 15-20 minute daily tasks
  • Behavioral economics principles applied
  • Dynamic skill level adjustment (CEFR A1-C2)
  • Tiered pricing based on daily achievement
Features
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意志が弱いんじゃない。逃げ場が、あるだけだ。 Kusariは、毎日の英語学習を「鎖」で習慣に変えるアプリです。読む、話すの2ステップ、1日15分ほど。意志の力ではなく、設計で続けます。 コミットメント・デバイス(自分への約束を仕組みで守る装置)の研究をもとに設計しています。Yaleの研究者らが立ち上げたstickKなどで知られる手法です。Kusariは同大学と提携・監修関係にはありません。 料金は、続けた日数で決まります。 通常価格 月¥5,000(自動更新)。直近30日の達成日数によって、翌月のご請求が5段階で変わります。 ・24日以上 ¥0 ・18〜23日 ¥1,000 ・12〜17日 ¥2,500 ・6〜11日 ¥4,000 ・5日以下 ¥5,000(通常価格) 日数に比例して安くなるのではなく、上の5段階で決まります。 割引の適用には、更新日の前にアプリ内で申請の操作が必要です(Appleの仕様上、自動では適用できません)。アプリが更新前にお知らせします。 最初の7日間は、登録なしでお試しいただけます。8日目にご登録いただくと、そこから30日間の無料トライアル(初回のみ)が始まり、最初のご請求はその後です。 お試し期間7日分の記録は、ご登録後のアカウントには引き継がれません。 サブスクリプションは自動更新です。期間終了の24時間前までに、iPhoneの「設定」>ご自身のApple ID>サブスクリプションから解約できます。 今は三日坊主でも大丈夫です。続けられる自分に変わるための仕組みだけ、用意しました。

Screenshots

Pengword4 screens
Kusari4 screens

Verdict

The call

The clearest difference is update cadence: Pengword at every 3 days against Kusari's every 10 days. Kusari's advantage is iOS requirement (15.1 vs 26.0). On price, ads, in-app purchases and device support there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Pengword sells 1 in-app purchase, starting at $2.99 per month and Kusari sells 1 in-app purchase, starting at $29.99 per month. Whichever you choose, the download price is not the number that matters.

UpkeepUpdate frequency

Pengword ships an update every 3 days, Kusari every 10 days. The most recent releases landed on November 9, 2026 and October 31, 2026 respectively.

Scorecard2 real differences · 6 level
Pengword versus Kusari: the parameters behind the verdict, then further details
ParameterPengwordKusari
PriceFreeFree
Positive reviews—100.0% of reviews
Update frequencyEvery 3 days — betterEvery 10 days
AdsNoNo
In-app purchasesYesYes
Monetization—Free with in-app purchases
DevicesiPhoneiPhone, iPod — better
Requires iOS26.015.1 — better
Further details — not scored
Size26 MB123 MB
Age rating4+4+
DeveloperToya NiiboriRYUTA ABE

In-app purchases

1 purchases

Pengword

Subscriptions1
  • Premium Monthly$2.991 Month
1 purchases

Kusari

Subscriptions1
  • Kusari Monthly1 Month trial$29.991 Month

Questions

Is Pengword free?
Pengword is free to download, with in-app purchases available.
Is Kusari free?
Kusari is free to download, with in-app purchases available.
Do Pengword or Kusari have ads?
Neither Pengword nor Kusari shows ads.
Which is updated more often, Pengword or Kusari?
Pengword ships an update every 3 days, and Kusari every 10 days. Most recently, Pengword was updated on November 9, 2026 and Kusari on October 31, 2026.

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