Destrava
English for Brazilians who understand it but freeze when they have to speak.
- 42 decks in 11 tracks
- 792 phrases and expressions in the decks
- 47 modules in the structures course
- 34 migrations in Supabase
Screenshots from a test build with a real account, in dark mode.
The problem
Many people who studied English for years understand a whole meeting and, when it is their turn to answer, nothing comes out. Vocabulary apps drill loose words. Nobody drills the ready-made answer for the stand-up, the interview, or the customer support call.
Who it’s for
Brazilian adults who need English at work and in daily life: tech professionals in meetings and code reviews, people going to a job interview, people who travel.
What we built
- Phrases by situation: 42 decks organized into 11 tracks, such as stand-up, code review, services, and social life. Each phrase comes with a translation and audio.
- Review at the right time: the FSRS algorithm schedules each phrase for the point where you are about to forget it.
- Structures course: 47 modules that teach you to build sentences, not just memorize them.
- Narrated stories: short stories in English with locally generated voice, to train your ear.
- Works offline: studying is saved on the device and syncs later.
- Free and Premium: part of the content is open, and the rest is unlocked by the server for subscribers.
Technical decisions
Content as immutable releases
Each content version is published to the database with checksums, and the audio has its own release key. The app never mixes text from one version with voice from another, and a version can be safely rolled back.
The client never grants access
The installed app ships only the free content and the samples. Premium content comes from the server only to people with an active entitlement. Modifying the app unlocks nothing.
Offline first, with an idempotent queue
Each card review goes into a local queue (outbox) and is sent to an idempotent function on the server. Resending does not duplicate progress, and studying does not depend on the network.
Providers behind interfaces
Scheduling, billing, login, and analytics sit behind our own interfaces. Switching the payment provider does not touch any screen.
Minimum version gate
Every request reports the app build. Builds that are too old receive only the update screen, instead of breaking silently.
AI in the process
The AI does not run inside the app. It is used in content production: translation, narrative drafts, and locally generated synthetic voice. Every generated audio file is transcribed back and compared to its text, to catch swapped or cut words. Full human review of the content is still in progress and is part of the launch plan.
Current status
The app runs internally, installed on test devices. Before Google Play, we still need the final signing key, the AAB package, the login setup for the store version, and these privacy and account-deletion pages.