A Chrome extension that instantly explains any text you highlight — in ADHD-friendly bullets, plain English (ELI5), detailed breakdowns, or your own custom prompt. Uses your own AI API key, runs entirely in your browser.
| Mode | What it does |
|---|---|
| ADHD-friendly | Short bullets, bold key terms, under 150 words — fast to scan |
| ELI5 | Simple analogies, no jargon, 2–4 sentences |
| Detailed | Structured breakdown with key concepts and context |
| Custom | Write your own system prompt — explain like a lawyer, summarise in one line, anything |
- Highlight to explain — select text on any webpage and the explanation appears instantly in the side panel
- Right-click menu — "Explain with Plainly" in Chrome's context menu as an alternative trigger
- History — last 20 explanations saved locally, each remembering its mode
- Enable / disable toggle — pause Plainly with one click without uninstalling
- Multiple AI providers — OpenAI, Groq (free tier), or any OpenAI-compatible endpoint (Ollama, n8n, etc.)
- BYOK — Bring Your Own Key. No Plainly server. No subscription.
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| ADHD mode — Wikipedia article | ELI5 mode — Terms of Service |
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| Right-click context menu trigger | Inline settings — provider, model, mode |
Install directly from the Chrome Web Store →
git clone https://github.com/coder-RT/plainly.git
cd plainly- Open Chrome →
chrome://extensions - Enable Developer mode (top right)
- Click Load unpacked → select the
plainly/folder - Click the Plainly icon in the toolbar to open the side panel
- Go to Settings → add your API key
Plainly works with any of these providers:
| Provider | Model | Cost | Get key |
|---|---|---|---|
| OpenAI | gpt-4o-mini (recommended) | ~$0.001 per explanation | platform.openai.com/api-keys |
| Groq | Llama 3.3 70B | Free tier available | console.groq.com/keys |
| Ollama | Any local model | Free (runs locally) | ollama.com |
| Custom | Any OpenAI-compatible API | — | Your endpoint URL |
Your API key is stored locally in your browser using
chrome.storage.sync. It is never sent to any Plainly server.
plainly/
├── manifest.json # Extension manifest (MV3)
├── background.js # Service worker — API calls, message routing
├── content.js # Content script — text selection detection
├── sidepanel.html/css/js # Side panel UI
├── options.html/css/js # Options page (legacy)
├── prompts/
│ ├── adhd.js # ADHD-friendly system prompt
│ ├── eli5.js # ELI5 system prompt
│ ├── detailed.js # Detailed system prompt
│ └── index.js # Re-exports all prompts
├── icons/ # Extension icons
└── screenshots/ # Store screenshots and mockups
Plainly collects zero data. No analytics, no telemetry, no backend server.
- Your API key stays in your browser (
chrome.storage.sync) - Selected text is sent directly from your browser to your chosen AI provider, using your own API key
- Explanation history is stored locally in your browser only
Read the full Privacy Policy →
# Install dev dependencies (icon generation script only)
npm install
# Regenerate icons from source
node scripts/generate-icons.jsTo edit prompts, modify the files in prompts/ — each mode is a separate file so you can tweak, add, or remove modes independently.
- Phase 2 — Proxy backend for users who don't want to manage API keys
- Keyboard shortcut to trigger explanation
- Export history to Markdown / Notion
- Per-site prompt preferences
- Firefox support
Issues and PRs are welcome. Please open an issue first to discuss what you'd like to change.
MIT © Plainly