{"slug": "show-hn-promptlab-local-first-chrome-sidepanel-for-llm-prompt-testing", "title": "Show HN: PromptLab – Local-first Chrome sidepanel for LLM prompt testing", "summary": "PromptLab, a local-first Chrome extension for testing LLM prompts, was released on Hacker News. The Manifest V3 side panel, built with React, TypeScript, and Vite, stores up to 20 prompt fixtures entirely in chrome.storage.local with no analytics, remote APIs, or cloud storage, ensuring data never leaves the machine.", "body_md": "Chrome extension (Manifest V3) for managing local prompt fixtures. Nothing leaves the machine: no analytics, no remote APIs, no cloud storage.\n\n- React + TypeScript + Vite\n- Tailwind CSS\n`@crxjs/vite-plugin`\n\nfor the extension build`chrome.storage.local`\n\nin the extension,`localStorage`\n\nin the browser preview\n\n```\nnpm install\nnpm run dev\n```\n\nOpens a local dashboard at `http://localhost:5173`\n\n. Add, edit, and delete up to 20 prompt fixtures. **Run Eval** is a stub for tomorrow’s LLM wiring.\n\n```\nnpm run build\n```\n\nThen in Chrome:\n\n- Open\n`chrome://extensions`\n\n- Enable\n**Developer mode** - Click\n**Load unpacked** - Select the\n`dist`\n\nfolder\n\nClick the extension icon to open the side panel.\n\nFor live reload while developing the extension:\n\n```\nnpm run dev:extension\n```\n\nLoad the generated `dist`\n\nfolder as unpacked. Keep the Vite process running.\n\n- Fixtures persist only in\n`chrome.storage.local`\n\n(or`localStorage`\n\nin the web preview) - No telemetry, fonts-from-CDN, or outbound requests in this app\n- Permissions:\n`storage`\n\n,`activeTab`\n\n, and`sidePanel`\n\n(needed to host the dashboard)", "url": "https://wpnews.pro/news/show-hn-promptlab-local-first-chrome-sidepanel-for-llm-prompt-testing", "canonical_source": "https://github.com/timgioh/PromptLab-Local-First-LLM-Prompt-Testing-in-Your-Browser", "published_at": "2026-09-01 08:33:50+00:00", "updated_at": "2026-09-01 08:56:27.101492+00:00", "lang": "en", "topics": ["developer-tools", "ai-tools"], "entities": ["PromptLab", "Chrome", "React", "TypeScript", "Vite", "Tailwind CSS"], "alternates": {"html": "https://wpnews.pro/news/show-hn-promptlab-local-first-chrome-sidepanel-for-llm-prompt-testing", "markdown": "https://wpnews.pro/news/show-hn-promptlab-local-first-chrome-sidepanel-for-llm-prompt-testing.md", "text": "https://wpnews.pro/news/show-hn-promptlab-local-first-chrome-sidepanel-for-llm-prompt-testing.txt", "jsonld": "https://wpnews.pro/news/show-hn-promptlab-local-first-chrome-sidepanel-for-llm-prompt-testing.jsonld"}}