Generated at your level
Every story is freshly generated and checked by trusted code against the words you know, so it sits just above your level instead of too hard or too easy.
Early access · audio-first
Learn a language
Learn a language
by ear.
lull plays you short stories in your target language, generated at your exact level. Hear a word you don't know? Tap once. It adapts the difficulty and brings the word back as spaced review - eyes closed, on a walk, or behind the wheel.
- Comprehensibility enforced by code
- Portuguese & Indonesian
Now playing · Brazilian Portuguese
Ela mora perto do mar e caminha na praia todas as manhãs.
Tap any word you don't know
The intermediate plateau
Past the beginner apps, not yet ready for native speed.
Beginner apps stay too easy and keep your eyes glued to a screen. Native podcasts and shows move too fast. lull lives in the gap: comprehensible input, just above your level, delivered by ear - so you keep moving forward instead of stalling.
The loop
One gesture, and the lesson tunes itself.
No decks to build, no grades to assign while you listen. The single tap drives everything that happens next.
- 01
Calibrate
A quick self-rating and a short comprehension probe estimate your starting level - no long placement test, no fake precision.
- 02
Listen
Press play. A short story unfolds in your target language, built from words you know plus a few new ones, at your exact level.
- 03
Tap
Hear a word you don't know? Tap once, anywhere. Eyes closed, on a walk, in the car - one gesture, no menus.
- 04
Adapt
lull attributes the tap to the right word, marks it for spaced review, and tunes the next story's difficulty to how you're doing.
- 05
Review
Due words come back woven into new stories and as quick flashcards graded by a spaced-repetition engine, so they actually stick.
What makes it work
Built for the way you actually learn.
One tap, eyes free
The whole screen is a single tap target. Mark a word you don't know without looking, then keep listening. No buttons, no typing.
Review that comes to you
Words you tap are scheduled with a real spaced-repetition engine and woven back into future listening, so review happens inside the flow.
Steer the story
Pick a genre - travel, food, sci-fi, daily life - and the stories lean that way, while the vocabulary stays exactly at your level.
Your own content
Point lull at a song or a video, or paste a transcript, and it builds a lesson around the words that are new for you.
A head start across languages
Already speak a related language? lull pre-seeds the vocabulary you share, so a new language doesn't start from zero.
Why the level is right
The model proposes. Code decides.
Language models leak words you haven't learned yet. lull never trusts a model to stay in bounds: it keeps a closed set of the words you know plus a few new ones, and a trusted validator checks every script and repairs any out-of-set word before you hear it. That is why the content reliably sits just above your level - comprehensible input, guaranteed by code, not by a prompt.
Languages
Two languages today, built to add more.
Language is a swappable, registry-driven dimension in lull, so new ones plug in cleanly.
Brazilian Portuguese
With a head start if you already speak Spanish - lull pre-seeds the thousands of words the two languages share.
Indonesian
The first language lull was built for, tuned end to end.
Questions
Good to know.
What is lull?
lull is an audio-first language-immersion app. You put in earbuds and listen to short stories generated in your target language at your exact level. When you hear a word you don't know, you tap once - anywhere on the screen. lull marks that word, schedules it for spaced repetition, and adjusts the difficulty of what comes next. Over time the unknown words shrink and review happens inside the listening rather than on a separate deck of flashcards.
How does lull work?
First a short calibration estimates your level from a self-rating plus a frequency-banded comprehension probe. Then lull generates a short story using words you already know, a few new ones, and any words due for review. Every script is checked by trusted code against your allowed vocabulary, so the content genuinely sits at your level - it is not left to the model to behave. You listen; you tap the words you don't know; lull attributes each tap to the intended word, reschedules it with a spaced-repetition engine (FSRS), and tunes the next story up or down based on how often you tapped.
Which languages does lull support?
lull currently supports Brazilian Portuguese and Indonesian. Language is a first-class, swappable dimension built on a registry, so more languages can be added. If you already speak Spanish and are learning Brazilian Portuguese, lull gives you a head start by pre-seeding the large shared and cognate vocabulary the two languages have in common, so you start higher and only drill the genuinely different words.
Can I use lull while driving or with my eyes closed?
Yes - that is the whole point. lull is audio-first and screen-optional. The default listening screen is a single blank tap target, so you can learn with earbuds in and your eyes closed, on a walk or a commute. Spaced review can also be done hands-available as quick audio-or-card flashcards when you have a moment to look.
Put in your earbuds. Press play.
Try lull in your browser - calibrate in a minute and start listening at your level.
Start listening