Web Llm
High-performance In-browser LLM Inference Engine
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What is Web Llm?
WebLLM is a high-performance, in-browser language model inference engine that brings large language models (LLMs) directly to web browsers using WebGPU for hardware acceleration. It enables developers to run powerful AI models like Llama, Phi, Gemma, Mistral, Qwen, and RedPajama entirely on the client side without any server-side processing, offering cost reduction, enhanced personalization, and privacy protection.
The tool provides full OpenAI API compatibility, allowing seamless integration with standard AI workflows including JSON-mode, function-calling, and streaming chat completions. It features a modular design that can be easily integrated into projects via NPM, Yarn, pnpm, or CDN, with support for web workers and service workers to offload heavy computation from the UI flow.
WebLLM is designed for web developers building AI-powered applications, researchers experimenting with client-side AI, and anyone wanting private, server-free AI conversations. The demo site serves research purposes only, and the project is open-source under the MLC-AI organization.
Custom model integration is supported through MLC format, allowing users to adapt WebLLM to specific needs. The engine supports Chrome extensions, real-time streaming interactions, and provides progress callbacks for model loading operations.
Web Llm pricing
Pricing model: Freemium
WebLLM is completely free and open-source. The package is available on npm (@mlc-ai/web-llm) under Apache-2.0 license. The demo site at webllm.mlc.ai is for research purposes only. No paid tiers or subscription plans exist - users can install via npm, yarn, pnpm, or use CDN directly without any cost.
Web Llm pros
- Runs LLMs entirely in browser without server processing
- WebGPU hardware acceleration for optimal performance
- Full OpenAI API compatibility with JSON-mode and function-calling
- Supports multiple models: Llama, Phi, Gemma, Mistral, Qwen, RedPajama
- Complete privacy with all computation happening locally
- Zero server costs for AI inference
- Streaming chat completions for real-time responses
- Web worker and service worker support forUI optimization
- Easy integration via NPM, Yarn, pnpm, or CDN
- Custom model integration through MLC format
- Chrome extension support for browser functionality extension
- Modular design hooks to any UI components
- Progress callbacks for model loading monitoring
- OpenAI-style chat APIs through MLCEngine interface
- Open-source project from MLC-AI community
Web Llm cons
- Requires WebGPU-compatible browser (Chrome, Brave, Edge only)
- Does not work on Safari or Firefox without WebGPU support
- iPhone limited to 1.5GB memory for webpage operations
- First run requires downloading multiple gigabytes of model weights
- Model download may fail on slow internet connections
- Requires powerful GPU with sufficient VRAM for larger models
- Limited model selection compared to server-based solutions
- Cannot run Phi 3 yet according to available models
Frequently asked questions about Web Llm
What is WebLLM?
WebLLM is a high-performance in-browser language model inference engine that brings large language models to web browsers with WebGPU hardware acceleration. It allows developers to build AI-powered applications directly within the browser environment, removing the need for server-side processing and ensuring privacy.
Which browsers support WebLLM?
WebLLM requires a WebGPU-compatible browser. It works on Chrome, Brave, and Edge browsers that support WebGPU. It does not work on Safari or Firefox due to lack of WebGPU support, except iPhone is limited to 1.5GB memory for webpage operations.
What models does WebLLM support?
WebLLM natively supports a range of models including Llama, Phi, Gemma, RedPajama, Mistral, Qwen (通义千问), and many others. Models are registered as ModelRecord instances and can be accessed through the MLCEngine interface.
How does model loading work?
Loading models requires downloading and can take significant time for the first run without previous caching. You should properly handle this asynchronous call using initProgressCallback to monitor progress. Subsequent visits load instantly from browser cache.
Is WebLLM free to use?
Yes, WebLLM is completely free and open-source under the Apache-2.0 license. The package is available on npm and there are no paid tiers or subscription plans. The demo site is for research purposes only.
Does WebLLM support streaming responses?
Yes, WebLLM supports streaming chat completions by passing stream: true parameter to engine.chat.completions.create. This enables real-time output generation which enhances interactive applications like chatbots and virtual assistants.
How do I use the OpenAI API with WebLLM?
WebLLM provides full OpenAI API compatibility through the MLCEngine interface. Chat completions are invoked using engine.chat.completions.create with OpenAI-style messages. Features include JSON-mode, function-calling, and streaming support.
Can I use custom models with WebLLM?
Yes, WebLLM supports custom model integration through MLC format. You can compile models into MLC format and integrate them easily, allowing you to adapt WebLLM to specific needs and scenarios for enhanced flexibility in model deployment.
What is the MLCEngine interface?
MLCEngine is the main API interface for WebLLM. It can be instantiated using the CreateMLCEngine factory function or by directly instantiating the MLCEngine class and using reload() to load models. All WebLLM APIs are exposed through this interface.