Comparison

SentenceDeck vs OpenKoto

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

Head to head
About

SentenceDeck

Features
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Practice the conversations you will actually have. Pick a scene — airport check-in, ordering coffee, a job interview — and SentenceDeck uses AI to write a short dialogue for your level. You say your lines; your partner's lines are played for you. It is shadowing, made real: hear each line, say it, then hear yourself back. No grades, no corrections, no leaderboards — just a calm, repeatable way to rehearse real situations out loud, in a hand-drawn sketchbook. HOW A SCENE WORKS 1. Choose from 30 everyday scenes in five categories: Travel, Daily Life, Work, Social and Emergencies 2. Pick your level (A2, B1 or B2) and a voice for each side of the dialogue 3. Practice line by line: listen to the reference, speak — recording stops when you stop speaking — then play yourself back. Play your own lines, swap to the other role, or practice both sides 4. Finish with a short recap: lines practiced, time spent and the lines you recorded again Line-by-line translations in your interface language are one tap away. A/B compare, sentence lock and playback speed (0.75Ɨ to 1.5Ɨ) are all there while you practice. A STAMP FOR EVERY SCENE Finish a scene and it is stamped into your passport, next to today's lines, your day streak and your total. My Scenes keeps every dialogue you have practiced, with all its versions, ready to search and practice again. DESCRIBE YOUR OWN SCENE Type a situation in one sentence — "Calling my landlord because the water heater is broken" — and get a dialogue written for it. Your description is sent to an AI service to write the dialogue, and the app asks for your permission before the first time. Everyday situations only; please leave out names and contact details. Any AI-written dialogue can be reported from the practice screen or the recap. READY OFFLINE 21 built-in English scenes (B1) come with audio, are free to practice and work without a connection, so you can start talking the moment you open the app. TWO WAYS TO WRITE A DIALOGUE • Standard: free, with a number of free dialogues every day • Detailed: richer context and more natural lines. Uses characters from your balance; the cost is shown before you start, and nothing is charged if writing fails TWO KINDS OF VOICE System voice: built into iOS. Free, offline, unlimited. Premium voice: natural, lifelike voices that speak each line with the mood of the scene. Premium audio is generated sentence by sentence as you practice and paid for in characters. The same sentence is cached for replay with the same voice settings; changing the voice may generate it again and use characters again. READ ALONG WITH YOUR OWN TEXT Paste an article, a script or presentation notes — or import a text file — and practice it sentence by sentence. Backup & Restore keeps the audio you generated. LANGUAGES Practice English, Chinese (Simplified and Traditional), Japanese, Korean, Spanish, French, Italian or German. The app itself speaks 10 interface languages, on iPhone and iPad, in light or dark mode. CHARACTER PACKS • 6,000 characters • 30,000 characters • 72,000 characters Characters never expire and are used for premium voice and Detailed dialogues. The App Store shows the local price for your region. Whether you are getting ready for a trip, a job interview, IELTS or TOEFL, or simply want to sound natural in everyday conversations, SentenceDeck gives you a focused speaking routine for the situations that matter to you. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://www.kuroneko-cmd.dev/privacy/sentencedeck/

About

OpenKoto

Features
Read full description

OpenKoto is an open-source, privacy-first language-learning app. Turn the articles, books, and videos you genuinely care about into study material, understand sentences in context, collect vocabulary, and review it on a schedule. Key features: • Paste text or import TXT, Markdown, and web content • Import TXT and EPUB books with automatic chapter splitting, in either a sentence-by-sentence view or the book's original layout • Import video and audio with SRT / VTT subtitles — or generate subtitles on device when you have none (requires iOS 26) • Subtitles follow playback sentence by sentence; tap a line to jump to it, loop a single sentence, change speed without changing pitch, and hide the text to shadow by ear • Read sentence by sentence, resume where you left off, and add bookmarks and highlights • Show word-level readings above Japanese and Chinese text (furigana / pinyin), generated entirely on device • Search the full text of everything you have imported — articles, book chapters, and media transcripts — and jump straight to the sentence • Save vocabulary, organize word packs, and use spaced-repetition review; jump from any card back to the sentence it came from • View reading and review statistics • Use the app in English, Simplified Chinese, or Japanese • Choose light, dark, and multiple visual themes • Send web pages or selected text to OpenKoto from the iOS share sheet Optional AI features use a bring-your-own-key model. Configure a compatible provider of your choice for translations and sentence explanations. API keys are stored in the iOS Keychain, while learning content and progress stay on your device. AI requests go directly from your device to your selected provider and do not pass through an OpenKoto app server. No account is required. Sample articles are included, so reading, vocabulary, and review features work without configuring an AI provider. OpenKoto is free and open source.

Screenshots

SentenceDeck4 screens
OpenKoto1 screens

Verdict

The call

The clearest difference is in-app purchases: OpenKoto at none against SentenceDeck's 3. OpenKoto also leads on update cadence (weekly vs every 6 weeks). On price, ads, device support and iOS requirement there is nothing between them.

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

CostPrice Ā· In-app purchases Ā· Ads Ā· Monetization

Both are free to download. SentenceDeck sells 3 one-off in-app purchases. OpenKoto asks for nothing beyond the download.

UpkeepUpdate frequency

SentenceDeck ships an update every 6 weeks, OpenKoto weekly. The most recent releases landed on October 15, 2026 and October 9, 2026 respectively.

Scorecard2 real differences Ā· 4 level
SentenceDeck versus OpenKoto: the parameters behind the verdict, then further details
ParameterSentenceDeckOpenKoto
PriceFreeFree
Update frequencyEvery 6 weeksWeekly — better
AdsNoNo
In-app purchasesYesNo — better
DevicesiPhone, iPadiPhone, iPad, Mac — better
Requires iOS17.0 — better18.0
Further details — not scored
Size36 MB9 MB
Age rating4+4+
Developer儇濂 任倍铭 刘

In-app purchases

3 purchases

SentenceDeck

One-time3
  • Credits 100$0.99
  • Credits 500$3.99
  • Credits 1200$7.99
None

OpenKoto

No in-app purchases

Questions

Is SentenceDeck free?
SentenceDeck is free to download, with in-app purchases available.
Is OpenKoto free?
OpenKoto is free to download, with no in-app purchases.
Do SentenceDeck or OpenKoto have ads?
Neither SentenceDeck nor OpenKoto shows ads.
Which is updated more often, SentenceDeck or OpenKoto?
SentenceDeck ships an update every 6 weeks, and OpenKoto weekly. Most recently, SentenceDeck was updated on October 15, 2026 and OpenKoto on October 9, 2026.

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