click to boop · drag a cheek

Windows 10/11 · bring your own model key

Your English buddy, always a click away

A small floating tutor that stays on top of your work, chats in English at your CEFR level, with a Portuguese translation or in Portuguese only when you need it, and turns quiet corrections into practice you actually remember.

Download for Windows View on GitHub

Free and local-first. The button downloads the installer directly. It is unsigned, so Windows SmartScreen may ask for confirmation. Install notes

bubo chat window showing a learner message, a friendly reply, and a corrections card with one fix

Features

Small window. Real practice.

A conversation partner that corrects without turning every reply into a lesson, then remembers what you got wrong. Choose replies in English, English with a translation, or Portuguese only.

Corrections that don't interrupt

bubo answers first, then shows the fix beside the conversation. You keep talking instead of stopping to study.

Spaced practice

Every correction becomes a card on a 1 / 3 / 7 / 21 / 45-day ladder. A miss comes back in ten minutes.

Progress that adds up

Streak, accuracy, a 14-day activity strip and the mistakes you practice most, all from your local history.

A buddy you can shape

Pick a voice from twelve personalities, then tune the shape, eyes, mouth and color. The mascot is yours.

Compact mode

A 400 × 280 card with the buddy in the header and a one-line composer. The full window is one click away.

Your provider, your key

Groq, OpenAI, OpenRouter, Ollama or any OpenAI-compatible endpoint. Bring a key and pick the model you like.

Beginner mode, no shortcuts

At A1/A2, the translation waits until you try. bubo gives a hint before the answer, you can pick a study focus, and work through a three-step mini-lesson with one exercise at a time.

Screenshots

A look inside

Real screens from the app: ready-made voices, the buddy editor, a chat with corrections, the mini-lessons, the practice deck, progress, history and compact mode. Click any screenshot to open it larger.

bubo buddy panel listing twelve ready-made personality voices such as Warm Coach, Dry Wit and Night Owl
Ready-made voices Twelve personalities, from Warm Coach to Night Owl. Picking one changes only the tone.
bubo buddy customization with the default purple round mascot, bars eyes, size L, straight tilt and no mouth, plus shape, color, eye and mouth controls
The default bubo Purple, round, bars eyes, size L, straight tilt and no mouth. Every part is editable.
bubo mini-lessons list with seven grammar and vocabulary topics
Mini grammar lessons Seven short rules, one exercise per step.
A bubo mini-lesson step explaining the verb to be and asking for a sentence in English
One rule at a time A short explanation, examples and one exercise to try.
bubo practice screen with a sentence to rewrite, the original context and a check button
Practice what tripped you Rewrite the sentence and get instant feedback.
bubo progress screen with a four-day streak, accuracy, a 14-day chart and most practiced mistakes
See the streak grow Accuracy, activity and your most repeated mistakes.
bubo history screen listing saved chat sessions with message counts and dates
Every chat is a session Reopen an old conversation or start a new one.
bubo empty state with the mascot, a short introduction and three conversation starters
Start with a prompt Open the app and pick a conversation starter, or type your own.
bubo compact mode: a wide card with the mascot in the header and a one-line message composer
Compact when you're busy A 400 × 280 card that keeps the conversation and the composer on one line.

Install

Running in under a minute

No account, no admin rights and no background service to configure.

  1. Download the setup

    Grab bubo-setup.exe directly, or browse older versions.

  2. Close bubo first

    If bubo is already running, quit it from the tray. The installer cannot replace an open executable.

  3. Run the setup

    The build is unsigned, so SmartScreen may say “Windows protected your PC”. Choose More info, then Run anyway.

  4. Launch it

    Open bubo from the Start menu. If nothing appears, run %LOCALAPPDATA%\bubo\bubo.exe directly.

  5. Add an API key

    Settings opens on first run. Paste a key, pick a model and choose your CEFR level. Groq is the default preset; OpenAI, OpenRouter, Ollama and custom URLs work too. At A1/A2, you also get the beginner mode with a study focus and mini-lessons.

Privacy

Your words stay yours

bubo has no backend of its own. There is no account to create and nothing to sync.

Only your model sees your messages

The text you send goes to the provider you configure and nowhere else. There is no bubo server in the middle.

Keys live in Windows

Your API key is stored in the Windows Credential Manager as bubo / llm-api-key, not in a plain-text config file.

No analytics, no account

Chat history and corrections live in a local SQLite database. There is no telemetry, and you can delete a session whenever you want.