# Show HN: An open-source app for IELTS preparation > Source: > Published: 2026-10-29 18:00:42+00:00 **BandReady** **Offline-first IELTS exam preparation for your own machine.** All four skills, a live AI voice examiner you actually talk to, and band-descriptor scoring — running against AI models you choose, local or cloud. You supply the model; the app is free and there is no account. [**Install**](#-install-users)  •  [Build from source](#-build-from-source)  •  [Contributing](https://github.com/Luxshan2000/ielts-prep/blob/main/CONTRIBUTING.md)  •  [Report an issue](https://github.com/Luxshan2000/ielts-prep/issues) IELTS Prep is an exam room, not a chatbot wrapper. You get authentic question formats, real timers, per-criterion band descriptors and longitudinal progress tracking. It is an Electron app around a Python sidecar that binds to loopback only, so your essays, recordings and scores stay on your disk unless you point it at a cloud provider yourself. **Not affiliated with the IELTS Partners** (British Council, IDP: IELTS Australia, and Cambridge University Press & Assessment). IELTS is a registered trademark of its owners. This is an independent, unofficial project; the name describes the exam it prepares you for and implies no endorsement by, or association with, the trademark holders. All practice material here is original and is not official IELTS test content. Band scores produced by this software are AI-generated estimates for practice only and do not predict official IELTS results. - **A live voice examiner** — real-time WebRTC conversation over pipecat 1.5, SmallWebRTCTransport and Silero VAD. You speak, it answers, it follows up. - **Full three-part mocks** — plus single-part drills, topic drills and quick chats when you have ten minutes rather than fifteen. - **A scored report every time** — timed transcript, four criterion bands, quoted evidence for each judgement, and per-turn audio replay. - **496 cue cards** across Parts 1 to 3, in 108 linked card sets over 20 topics. The live call has been confirmed at a real microphone by the project owner. Headless Chromium cannot establish the peer connection, so no automated test guards it. - **All three task types** — Academic Task 1 (charts, tables, processes and maps rendered from a structured chart spec), General Training Task 1 letters, and Task 2 essays. - **A pre-check before you spend a model call** — it catches an off-topic or too-short answer while you can still fix it. - **Character-anchored inline annotations** — each error is pinned to the exact offsets in your text, with a fix and an explanation. - **A rewrite loop and an on-demand band 8/9 model answer** , so you can see the gap rather than guess at it. - **102 prompts** with chart specs and band ladders. - **Full Academic and General Training tests** — 3 passages, 40 questions, 60 minutes — plus single-passage practice and question-type drills. - **Every IELTS question type** , auto-marked with the real matching rules: case folding, abbreviations, thousands separators, hyphen and space equivalence, word limits. - **A review that explains the trap** — answer key, anchoring paragraph, explanation, and a "why was I wrong?" analysis. - **12 tests** (8 Academic, 4 General Training) over 36 passages, 480 questions, 15 question types. - **Audio synthesised on your machine** — Kokoro TTS renders each script per role and per accent on first play, then caches it. A test ships as kilobytes of script, not megabytes of audio. - **Exam-faithful playback** — plays once, no seeking, with a proper transfer window. - **Per-part practice with transcript reveal** , and the same auto-marking engine as Reading. - **7 tests** over 43 scripts across UK, US and AU voices — 415 questions, 8 question types, including map labelling rendered from shipped SVGs. - **An FSRS bank fed by your own mistakes** — errors from your writing and speaking arrive as suggestions you accept or dismiss. - **Six exercise types** — flip, cloze, use-in-sentence with LLM checking, collocation, audio recall and speaking drill. - **A grammar syllabus, not a quiz bank** — 156 points, each naming the false rule learners are usually taught, drilled up a six-rung mastery ladder. - **99 reference articles** across 8 chapters that are never locked, because someone who does not know what a modal is has to be able to look it up first. - **An offline WordNet dictionary** for double-click lookups anywhere in the app. - **Fluency signals from your own audio** — speech rate, pause profile, filled pauses, and low-confidence word flagging. - **Minimal-pair perception drills and word-stress tapping** , with reference audio rendered on demand. - **No accent score, ever.** IELTS marks intelligibility, not how close you sound to any particular English. These signals come from speech-recognition confidence, which can tell you a word was hard to make out but cannot tell you a sound was wrong. You get flags and drills, never a pronunciation band and never the word "mispronounced". - **A placement test that seeds a study plan** — four band estimates become a dated plan with daily sessions that adapts to your results. - **Local SQLite with Alembic migrations** , so an update never means losing your history. - **Jobs with real progress and cancellation** — anything slower than a second returns a job id you poll. - **Importable and exportable `.brpack` content packs** , plus a full data export. - **Dark and light themes** , and keyboard-usable timers and test players. - **The sidecar binds to loopback only** and requires a per-launch bearer token. Nothing else on your machine can call it. - **Provider API keys are encrypted at rest** with a per-install key, masked in the UI, and redacted from every log line. - **Recordings and transcripts stay in your data directory.** There is no BandReady server to send them to. - **Cloud is opt-in and text-only for marking** — if you configure a cloud LLM, it sees the essay or transcript you are having marked, and nothing else. - **Model weights are never bundled and never committed.** They download on first run into your data directory, or get hard-linked from caches you already have. Not captured yet — they land with the first tagged release rather than sitting here as six broken image icons. | Screen | File to drop in | Screen | File to drop in | |---|---|---|---| | **Dashboard** — band trend, streak, today's session | `docs/screenshots/dashboard.png` | **Speaking** — a live session mid-turn | `docs/screenshots/speaking.png` | | **Writing** — the desk with an annotated evaluation | `docs/screenshots/writing.png` | **Reading** — the test player and palette | `docs/screenshots/reading.png` | | **Listening** — a test part with audio playing | `docs/screenshots/listening.png` | **Vocabulary** — the review player | `docs/screenshots/vocab.png` | [`docs/screenshots/README.md`](https://github.com/Luxshan2000/ielts-prep/blob/main/docs/screenshots/README.md) holds the capture contract. Building from source is the supported route today, and it takes about fifteen minutes on a fast connection. Two ways in: 1. **Build it from source.** This is the supported path, and it takes about fifteen minutes on a fast connection. Jump to[Build from source](#-build-from-source) . 2. **Run the release workflow yourself.**[`.github/workflows/release.yml`](https://github.com/Luxshan2000/ielts-prep/blob/main/.github/workflows/release.yml) builds on Windows and macOS runners and attaches installers to a GitHub pre-release. It is`workflow_dispatch` only, so you need push access to this repository or to your own fork. Whichever route you take, the first launch needs a network connection so it can fetch model weights (roughly 340 MB for the voice, more if you want local speech-to-text). Everything after that runs offline. Builds are unsigned, so both systems ask once before they will run a new app. This is what they ask and what to press. - **macOS** — open**System Settings → Privacy & Security** , scroll to the message about the app being blocked, and click**Open Anyway** . Right-click then Open no longer works on macOS 15. - **Windows** — SmartScreen shows "Windows protected your PC". Click**More info** , then**Run anyway** . After that first launch neither system asks again. **Prerequisites** Tool Version Why [Node.js](https://nodejs.org)20 or newer Electron shell and Vite renderer [pnpm](https://pnpm.io)9 ( `corepack enable` pins 9.12.0)workspace package manager [Python](https://python.org)3.11 the sidecar [uv](https://docs.astral.sh/uv/)latest Python environment and lockfile **1. Clone and install the JavaScript workspace.** ``` git clone https://github.com/Luxshan2000/ielts-prep.git cd bandready pnpm install ``` **2. Install the Python sidecar.** ``` cd sidecar && uv sync --extra dev --extra voice && cd .. ``` The `voice` extra is large — pipecat, torch and faster-whisper come to roughly 2 to 3 GB of wheels — but it is what makes the live speaking module work. Drop `--extra voice` for a text-only install and everything except live speaking still runs. **3. Start everything.** ``` node scripts/dev.mjs ``` That spawns the sidecar on a random loopback port, waits for the health handshake, starts Vite, and opens Electron. Useful variants: ``` node scripts/dev.mjs --browser # no Electron: fixed-port sidecar + Vite in a plain # browser (this is the mode the E2E suite drives) node scripts/dev.mjs --no-mock # use your real configured providers instead of mocks node scripts/dev.mjs --port 5273 --sidecar-port 8710 ``` **4. Run the tests** (optional, but it tells you the install is sound). ``` uv run --project sidecar pytest sidecar/tests/ -q # 1,352 tests uv run --project sidecar ruff check sidecar/bandready sidecar/tests cd app && pnpm exec tsc --noEmit -p tsconfig.json && pnpm test ``` **5. Package an installer** (optional). The bundle carries a relocatable CPython plus the sidecar's venv, because the app has to run on a machine with no Python. ``` node scripts/stage-sidecar.mjs --arch arm64 --voice pnpm --filter bandready-app build node scripts/build-electron.mjs cd app && pnpm exec electron-builder --config electron-builder.yml --mac dmg --arm64 ``` Installers land in the repository-root `dist-electron/`. A macOS arm64 DMG comes to roughly 156 MB without the voice extra. `stage-sidecar.mjs` builds the venv for the *host* platform, so a Windows installer cannot be produced from a Mac — that is what the release workflow is for. BandReady never ships a model or an API key. You pick exactly one LLM, one STT and one TTS under **Settings → Providers**. The screen detects what is already running on your machine and offers it first, and **Verify** sends one real request and lists the models the endpoint actually serves. | Preset | Modalities | Kind | Key | Notes | |---|---|---|---|---| | **Ollama** | LLM | local server | none | The easy local start. `ollama pull qwen3:14b` , base URL`http://127.0.0.1:11434/v1` . | | **OpenRouter** | LLM, STT, TTS | cloud | `sk-or-...` | One key covers all three. Base URL is locked to `https://openrouter.ai/api/v1` . | | **Local Whisper** | STT | in-process | none | faster-whisper, int8 on CPU by default. Required for pronunciation feedback. | | **MLX Whisper** | STT | in-process | none | Apple Silicon only. `large-v3-turbo` runs realtime on an M-series chip. | | **Kokoro** | TTS | in-process | none | An 82M ONNX voice model. The default everywhere, and what renders listening audio. | | **Custom OpenAI-compatible** | LLM, STT, TTS | anything | optional | Point it at OpenAI, Groq, DeepSeek, `mlx_lm.server` ,`llama.cpp` , or your own gateway. Every field is editable. | Two things are worth knowing. Model fields are closed dropdowns wherever the endpoint can be asked what it serves — a plausible-looking model name that 404s deep inside a provider surfaces three screens away as "the practice engine reported an error", and that is a bad afternoon for someone who came here to practise English. And pronunciation feedback needs *local* Whisper: a remote transcript carries no per-word confidence, so there is nothing for the fluency analysis to read. **Model weights are never bundled.** On first run, onboarding lists what your chosen presets need and downloads it into `/models/` as a resumable, cancellable background job. | Artifact | Used by | Size | |---|---|---| | Kokoro TTS v1.0 ( `.onnx` plus voice pack) | Listening audio, the examiner's voice | ~340 MB | | faster-whisper `base` /`small` /`large-v3-turbo` | Local speech-to-text | 145 MB / 484 MB / 1.6 GB | | MLX Whisper large-v3-turbo | Local speech-to-text on Apple Silicon | ~1.5 GB | | English WordNet | Offline dictionary lookups | ~30 MB | If you already have those files, the sidecar finds and **hard-links** them at startup rather than downloading again — it checks `~/.cache/pipecat/kokoro-onnx/`, `~/.cache/huggingface/hub/`, `$HF_HOME`, and anything on `BANDREADY_MODEL_SEARCH_PATH`. Adoption is instant, costs no extra disk, and leaves the original untouched. Set `BANDREADY_ADOPT_LOCAL_MODELS=0` to keep BandReady out of your caches entirely. Set the API key field to the literal `${OPENROUTER_API_KEY}` (any `${VAR}` works) and the key is read from the environment at request time instead of being stored: ``` export OPENROUTER_API_KEY='sk-or-...' node scripts/dev.mjs ``` Only variables whose names end in `_API_KEY` reach the sidecar. A missing variable produces a precise error naming it, never a silent auth failure. On macOS an app launched from Finder inherits nothing from your shell, so put the value in `/.env` instead — or just paste the key into Settings, where it is encrypted at rest with a per-install key. | OS | Path | |---|---| | macOS | `~/Library/Application Support/BandReady` | | Windows | `%APPDATA%\BandReady` | | Linux | `$XDG_DATA_HOME/BandReady` (default`~/.local/share/BandReady` ) | One SQLite database, your settings, the encryption key, downloaded models, generated audio, voice recordings and installed content packs all live under that one directory. Deleting it resets the app completely. - **[CONTRIBUTING.md](https://github.com/Luxshan2000/ielts-prep/blob/main/CONTRIBUTING.md)** — dev setup, the module map, and how to add a route or a screen. The one document to read before your first change. - **[SECURITY.md](https://github.com/Luxshan2000/ielts-prep/blob/main/SECURITY.md)** — the security model, what stays local, and how to report a vulnerability privately. - **[CODE_OF_CONDUCT.md](https://github.com/Luxshan2000/ielts-prep/blob/main/CODE_OF_CONDUCT.md)** — Contributor Covenant 2.1. - **[CHANGELOG.md](https://github.com/Luxshan2000/ielts-prep/blob/main/CHANGELOG.md)** — what has changed, in Keep a Changelog format. - **[docs/IMPLEMENTATION-STATUS.md](https://github.com/Luxshan2000/ielts-prep/blob/main/docs/IMPLEMENTATION-STATUS.md)** — what is built, what is not, and the evidence for each claim. The most honest file in the repository. - **[docs/DEVELOPMENT.md](https://github.com/Luxshan2000/ielts-prep/blob/main/docs/DEVELOPMENT.md)** — dev-mode architecture, debugging, log and data locations, resetting local state. - **[docs/REPOSITORY.md](https://github.com/Luxshan2000/ielts-prep/blob/main/docs/REPOSITORY.md)** — the tree around the code: what is tracked, what is generated, and which docs to trust. - **The content banks** , one document each — what ships, the schema, and how to author more:[reading](https://github.com/Luxshan2000/ielts-prep/blob/main/docs/READING-CONTENT.md) ·[listening](https://github.com/Luxshan2000/ielts-prep/blob/main/docs/LISTENING-CONTENT.md) ·[speaking](https://github.com/Luxshan2000/ielts-prep/blob/main/docs/SPEAKING-CONTENT.md) ·[grammar and vocabulary](https://github.com/Luxshan2000/ielts-prep/blob/main/docs/GRAMMAR-VOCAB.md) ·[theory](https://github.com/Luxshan2000/ielts-prep/blob/main/docs/THEORY-CONTENT.md) . Writing has no such document yet. - **[docs/plan/README.md](https://github.com/Luxshan2000/ielts-prep/blob/main/docs/plan/README.md)** — the index to twenty-two numbered design documents written before implementation began. This is design*intent* , not status. Much of it shipped differently, and where the plan and the code disagree the code is right. ``` bandready/ ├── app/ Electron shell + React renderer (pnpm workspace "bandready-app") │ ├── electron/ main, preload, sidecar spawn/health/teardown — the Node side │ ├── src/features// one directory per screen: route.tsx, page.tsx, store.ts │ ├── src/components/ui/ the shared design-system kit │ └── build/ electron-builder buildResources — NOT build output ├── sidecar/bandready/ the Python FastAPI backend │ ├── server/routes/ one module per API family, auto-discovered at startup │ ├── server/auth.py loopback guard, origin guard, bearer token │ ├── security/secrets.py credential encryption and log redaction │ ├── scoring/ srs/ curriculum/ voice/ audio/ pron/ providers/ │ └── db/ migrations/ SQLAlchemy 2.0 models + Alembic ├── content/core-en/ the shipped CC0 content pack, plus per-module authoring trees ├── tools/content/ the pack pipeline CLIs: merge_*.py, then build.py, then validate.py ├── scripts/ dev.mjs, build-electron.mjs, stage-sidecar.mjs ├── e2e/ Playwright specs, driven against a real sidecar in browser mode └── docs/ everything above, plus the numbered design set docs/plan/00 to 18 ``` **Two seams are auto-discovered, and using them never means editing a registry.** - **A sidecar route** is a new file in`sidecar/bandready/server/routes/` exposing a module-level`router` .`discover_routers()` imports every module in that package at startup; one that fails to import is logged and skipped, so a half-finished feature cannot stop the app booting. - **A screen** is a new`app/src/features//route.tsx` that default-exports`defineFeatureRoute(...)` .`App.tsx` finds it with`import.meta.glob` , and the sidebar is built from the same objects. Editing `server/app.py`, `App.tsx` or `Sidebar.tsx` to register something is a mistake, not a shortcut. [CONTRIBUTING.md](https://github.com/Luxshan2000/ielts-prep/blob/main/CONTRIBUTING.md) sections 3 and 4 have a working template for each. One collision to know about: repository-root `build/` is packaging output and is gitignored, while `app/build/` is *tracked* electron-builder resources. Likewise root `dist-electron/` holds installers and `app/dist-electron/` holds compiled bundles. The `.gitignore` rule is anchored with a leading slash for exactly that reason. Bug reports, content fixes and pull requests are welcome. [CONTRIBUTING.md](https://github.com/Luxshan2000/ielts-prep/blob/main/CONTRIBUTING.md) has the setup, the house rules, the two seams and the content pipeline. Everyone taking part is expected to follow the [Code of Conduct](https://github.com/Luxshan2000/ielts-prep/blob/main/CODE_OF_CONDUCT.md). The most useful thing you can send today is a wrong answer key, a broken question, or a report that the app does not boot on your platform. The shipped keys were authored and machine-validated, and nobody has independently checked them. **Does it really work offline?** Yes, once the models are on disk. The examiner, the transcription and the listening audio all run locally, and the database is a file on your machine. Three exceptions, all of them things you can see: the first run downloads model weights, any cloud provider you configure gets what you send it, and a *packaged* build asks GitHub Releases every six hours whether a newer version exists. That last one sends nothing about you, and it is off entirely in a dev build. **Does my voice leave the machine?** Not by default. Recordings are written to `/media/speaking//` and stay there. If you choose a cloud speech-to-text provider, your audio goes to that provider — that is what choosing it means. With local Whisper selected, no audio ever leaves. **Do I need an API key?** No, if you run everything locally: Ollama for the examiner, faster-whisper for speech-to-text, Kokoro for the voice. Yes, if you would rather use OpenRouter or another cloud endpoint. There is no BandReady account either way. **Is it free?** The software is MIT-licensed and the content is CC0. There is no subscription and nothing is metered. If you point it at a paid API you pay that provider directly — writing evaluation against a mid-size model measured at roughly $0.0002 per essay. **How accurate are the band scores?** Not proven. They are spot-checked against a real model (a strong essay scored 8.0, a weak one 5.0, both plausible) and have never been calibrated against expert-marked samples. Treat them as directional feedback on your writing, not as a predicted result. **What is missing?** Code signing and notarization, any Windows or Linux build that a human has run, automated coverage of the live voice call, scoring calibration, and an independent check of the answer keys. [docs/IMPLEMENTATION-STATUS.md](https://github.com/Luxshan2000/ielts-prep/blob/main/docs/IMPLEMENTATION-STATUS.md) lists the rest without flinching. **Is this affiliated with IELTS?** No. See the notice near the top. All practice material here is original and none of it is official test content. BandReady is licensed under the [MIT License](https://github.com/Luxshan2000/ielts-prep/blob/main/LICENSE) — copyright © 2026 Luxshan Thavarasa. The first-party practice content under `content/` is released separately as **CC0-1.0**, so you can reuse, remix or ship it however you like. Models you download are covered by their own licences, and BandReady redistributes none of them. One caveat for anyone redistributing a build: the local TTS engine `kokoro-onnx` depends on `phonemizer-fork` and `espeakng-loader`, which carry GPL-3.0 terms. If you ship a binary that bundles the voice extra, the licence of that combined work is a question you need to answer for yourself. The source in this repository is MIT.