AI agent for learning languages
Learn Spanish from anything you love
Add a video, book or article, or ask for a topic. Subtlex turns it into Spanish lessons at your level.
If you can watch it, read it or paste it, you can learn Spanish from it
In Subtlex, you choose what you study.
la verdad, lo estuve posponiendo semanas
Videos
The YouTuber you watch every week
00:41:07,220 → 00:41:09,010
No puedes irte sin más.
00:41:09,400 → 00:41:12,150
No te voy a dejar tirado. Esta vez no.
00:41:12,600 → 00:41:14,000
Shows & movies
The series you’re watching, through its subtitles
CAPÍTULO PRIMERO
En un lugar de la Mancha, de cuyo nombre no quiero acordarme, no ha mucho tiempo que vivía un hidalgo de los de lanza en astillero…Books
The novel on your nightstand, in the original
medium.com/@lucia.ferrer/por-que-los-equipos-remotos-acaban-escribiendo-mas-8a1d4c6e2f90
Por qué los equipos remotos acaban escribiendo más
El trabajo asíncrono te obliga a ser explícito con decisiones que antes se tomaban en el pasillo.
Articles
News, blogs, docs: anything with a link
oye, ¿podemos pasar la llamada al jueves?
claro, hoy estoy hasta arriba de todo
perfecto, hablamos
Any text
Emails, chats, lyrics, notes: paste them in
Write a dialogue at a coffee shop. I’m B1, I want to sound more natural
topic · B1
Any topic
Nothing at hand? Ask, and the agent writes it at your level
Subtlex reads all of it, counts every word and how often it appears, and starts you on the most frequent ones you don’t know yet, so you understand more, faster.
They teach sentences nobody says
Other apps
Subtlex
Same catalog for everyone
Your own content
Made-up sentences
Real Spanish
Stop helping around B1
Grow with you, beginner to advanced
Lessons on their schedule
Lessons on your goals
Just three steps
- 01Check your levelTick the words you know. It takes 30 seconds.
- 02Bring something you likeUpload it, paste it, or ask the agent for a topic.
- 03Practice what’s due, every dayLearn new words, then hear them, say them and write them. Each word comes back right before you’d forget it.
Everything a tutor would do
La revisión de código era nuestro mayor cuello de botella.
cuello de botella/ˈkweʎo ðe βoˈteʎa/
Definition in context
Here: the step that slows the whole team down.
Ask AIUnderstand every word
Tap any word to get its meaning in that sentence, hear it and see how it’s used. Still unsure? Ask the AI.
Next
WritePractice every skill
Listen, speak and write with your new words. The AI corrects you when you speak.
cuello de botellareview today
dar marcha atrásin 2 days
a producciónin 6 days
subirin 3 weeks
reuniónknown
Never forget what you learned
Subtlex reminds you about each word at the right moment and skips the ones you know.
Starting from zero? We’ll go slower.
Tap “I'm a complete beginner, skip the test” and get 31 ready-made lessons in order, from greetings to talking about yesterday. The agent keeps its sentences short and explains everything in your language.
Pay only for what you use
No subscription. You pay in tokens, and each AI action costs what it uses.
Why I built Subtlex
I’m Leven, an engineer and team lead who left a big corporation to build Subtlex on my own. I love learning languages, and I was tired of apps that stop being useful once you pass the basics.
None of them would let me learn from Oppenheimer, a book I’d just bought or the game I was playing. So I built one that learns from whatever you care about.
I read every message, so I’d love to hear your feedback.
FAQ
YouTube videos, subtitles, books, articles and websites, or any text you paste. You can also ask the agent to write something on any topic.
It analyzes all of your content first: it counts every word and phrase precisely, and how often each one appears. Then it gives you the most frequent ones you don’t know yet. They make up most of the text, so every word you learn makes more of it clear, and you understand it faster.
Any, from your very first words to advanced. A 30-second test sets your level, and every lesson follows it as you grow. Starting from zero? Choose “I'm a complete beginner, skip the test” and get a ready-made path of 31 beginner lessons in order: each one becomes a course in a tap, and the agent keeps its sentences short and explains everything in your language.
ChatGPT waits for your question and forgets the answer. Subtlex comes to you: it builds each day’s lessons from the words that are due and reminds you to take them. Reviews follow FSRS, a spaced repetition model based on memory research, so each word returns right before you’d forget it. It picks the words worth learning by how common they are and what fits your level, keeps every word you know or learn in your own dictionary, and finds examples of a word across all your courses. This is exact data about you, stored in your account. Neural networks don’t keep data like this. They can only guess it.
Duolingo keeps you busy with points, gems and streaks, and everyone gets the same made-up sentences. Subtlex has no points to chase. Every lesson is made only from your content and your words: the ones you don’t know yet, from the series you watch or the book you read. You read and watch them in context, then listen, speak and write until they stick, so no minute goes to words you’ll never use. And the more content you add and lessons you take, the better the agent knows you and the more precise it gets, from beginner to advanced.
What you spend on AI features. You start with 200,000 free ones, and each action costs what it uses.
Not a language learning game
Learn Spanish from what you love
Your videos, books and texts, turned into Spanish lessons.