"Flash Fluency: Korean" - Hangul to C1 with sentence construction coaching and syllable-level pronunciation feedback
Hi all! I'm on my business account right now, but I've been part of the community personally for the past couple of years and wanted to share the Korean language learning app I've been building since 2024. You can find "Flash Fluency: Korean" on both the iOS App Store and Google Play. Take a look and let me know what you think! Any feedback would be greatly appreciated! If you'd like to track the project, our discord and socials can be found at www.flashfluency.net
Why am I building Flash Fluency?
When I first started learning Korean there were a lot of tools available and of course there still are. But the overall learning ecosystem felt disjointed and mostly lacking. I learned Hangul through some random youtube channel - but it wasn’t actually assessing my pronunciation capability. I was using Anki for learning vocab but I wasn't progressing my ability to actually utilize those vocab in sentences, nor listen and comprehend them. TTMIK and HowToStudyKorean progressed my grammar quite well but I ended up forgetting a lot of what I learned. I later found out someone had made an Anki deck for grammar review! But at the time I had absolutely no idea that existed, and even still that's not going to help me with active sentence construction. I ended up learning to speak through months of 1:1 language exchange, but finding a solid language exchange partner is difficult especially with a 12 hour time zone difference between where I lived and Korea. So what am I actually getting at?
Learning Korean is difficult and disjointed and frustrating and I simply want to create the system that makes the journey a bit simpler. One system for vocab, grammar, reading, listening, and active production. With a PhD in physics and 7 years of experience in machine learning and conversational AI, I was confident I could build the solution, so I set out to build it.
Who is this for?
- Absolute beginners: Start with our Hangul and Foundational Curriculums (more below).
- Beginners and intermediates: Our core learning loop (reading, listening, cloze, translation, pronunciation) progresses not only your comprehension but your ability to actively construct and speak sentences in tandem. Everything adapts to your level so you're always learning and never overwhelmed.
- Advanced: Not yet fully supported. Features for advanced learners are in production.
- English to Korean only (currently)
Core Features
+1 SRS (Comprehensible Input + Spaced Repetition)
By tracking your proficiency per vocab, per grammar, and per exercise, the app provides sentences that include one new item at a time across reading, listening, cloze, translation, and pronunciation. You're always learning but never overwhelmed, and the system monitors your last encounter with each item to ensure timely review.
Hangul and Foundational Curriculum
For brand new learners: a Hangul curriculum with natively voiced snippets for every unique syllable and syllable-level pronunciation feedback from our custom trained model to get you speaking accurately from the start. The Foundational Curriculum then gets you building your first sentences before entering the core learning loop.
Syllable-Level Pronunciation Feedback
I trained a model to provide syllable-level pronunciation feedback. Most apps use models that predict what you were trying to say, so as long as you're roughly close they tell you "Perfect!" Flash Fluency analyzes what you actually said acoustically, so you get honest feedback. The app also introduces you to every Korean pronunciation rule (e.g. 연락 -> 열락) and makes sure you're familiar with all sound change rules through targeted practice.
Translation / Sentence Construction Coach
Too many systems focus only on input. Flash Fluency gives you sentences right at your level via the +1 system and asks you to translate them into Korean. As long as your sentence is natural and grammatically correct, it counts. We don't force you to guess one exact reference sentence. You get feedback on your grammar, vocab usage, and naturalness.
Instant Feedback
Tap any vocab or grammar item for a mini-lesson. We currently have 7000+ vocab and ~315 grammars. Still confused? Ask Flash, the embedded AI assistant, any question you have about the exercise.
Pricing
Up until June 1st we're having a free beta period! Utilize all of the app as much as you'd like!
Flash Fluency uses a freemium model. Free users get roughly 15 to 20 minutes of daily study across exercises that don't require per-user AI processing (reading, listening, cloze, pronunciation). Paid plans unlock unlimited core non-AI exercises + AI-driven features like translation grading and the Ask Flash assistant.
Current Exercises
Translation, Pronunciation, Reading, Listening, Fill-in-the-Blank
Coming Next (End of Year 2026)
- AI-assisted writing exercises
- Capstone conversational exercises to put your vocab and grammar to use in various real world scenarios
- A content-to-curriculum system that lets you turn anything (a K-drama script, a news article, a song) into personalized lessons (learn the vocab & grammar via our +1 learning loop)
Screenshots
fixing the resolution issue now
