I built a zero-backend, browser-only alternative to Open WebUI and heavy LLM stacks

Most open-source LLM chat interfaces follow the exact same blueprint: a heavy Python or Node.js backend, a Postgres/Redis database, and a multi-container Docker Compose setup just to pass a JSON prompt to an API. If you just want a clean, responsive workspace to inspect token counts, test system prompts, or chat with your local Ollama instance, deploying 2GB+ of Docker containers is massive overkill. That’s why I built Lab - a lightweight, completely serverless, local-first web environment for LLMs. 💡 Core Architecture - Zero Backend: Everything executes entirely on the client side in your browser. - Local Storage via IndexedDB: Chats, model configs, system prompts, and API keys are persisted locally in your browser using Dexie.js. Nothing ever touches my servers. - Surgical Context Controls: - Exact token usage breakdown per message: User vs. Assistant vs. Tool vs. System. - Message Pinning: Lock essential system instructions or context anchors in place to prevent them from being pruned when managing context windows. - Collapsible code blocks and raw JSON payload inspectors. - Multi-Provider Support: Seamlessly switch between Anthropic, OpenAI, OpenRouter, Google Gemini, and local models via Ollama. - Offline & PWA Ready: Installable as a native desktop or mobile PWA with background service worker caching. 🛠️ Working with Local Models (Ollama) Since Lab runs entirely in your browser over HTTPS, connecting to a local Ollama instance (http://localhost:11434 ) requires allowing browser cross-origin requests. Simply set the environment variable on your Ollama host: # Linux (systemd) sudo systemctl edit ollama.service # Add: [Service] Environment="OLLAMA_ORIGINS=*" Restart Ollama, and Lab connects instantly directly from your browser tab. 🔗 Links & Code The project is fully open-source under the MIT license: - Web App (Live Demo): https://labstudio.tech - GitHub Repository: https://github.com/Talos-popcorn/lab Feedback, bug reports, and PRs are more than welcome! Top comments (0)