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AI Frameworks · mlc-ai

web-llm

WebLLM is a TypeScript-based engine that runs large language models directly in web browsers using WebGPU acceleration, with no server required. It provides OpenAI API compatibility and supports models like Llama, Phi, Gemma, and Qwen out of the box.

Source: GitHub — github.com/mlc-ai/web-llm
18.3k
GitHub stars
1.3k
Forks
TypeScript
Primary language
Apache-2.0
License (OSI-approved)

Key facts

Objective fields from the source. Values we can't verify are shown as “Unknown” rather than guessed.

FieldValue
Repositorymlc-ai/web-llm
Ownermlc-ai
Primary languageTypeScript
LicenseApache-2.0 — OSI-approved
Stars18.3k
Forks1.3k
Open issues148
Latest releasev0.2.83 (2026-04-24)
Last updated2026-06-09
Sourcehttps://github.com/mlc-ai/web-llm

What web-llm is

WebLLM leverages WebGPU for GPU-accelerated LLM inference in-browser, built on the MLC LLM compilation framework. It offers streaming chat completions, JSON-mode structured generation, OpenAI API-compatible endpoints, and flexible cache backends (Cache API, IndexedDB, OPFS, Cross-Origin Storage).

Quickstart

Get the web-llm source

Clone the repository and explore it locally.

terminalbash
git clone https://github.com/mlc-ai/web-llm.gitcd web-llm# follow the project's README for install & configuration

Need it deployed, integrated, or customized instead? DEV.co ships production installs.

Best use cases

Privacy-First AI Assistants

Build chatbot and assistant applications where model inference stays entirely on-device, avoiding data transmission to external servers and meeting privacy-first product requirements.

Offline Web Applications

Develop web apps that function without constant server connectivity by embedding LLM inference directly in the browser, suitable for progressive web apps and offline-capable platforms.

Low-Latency Interactive Experiences

Create real-time, streaming chat interfaces and AI-powered features where local GPU acceleration reduces inference latency compared to client-server round-trips.

Implementation considerations

  • Model download and compilation on first run can be lengthy; implement robust progress callbacks and user guidance for initial load experience.
  • Browser storage limits (Cache API, IndexedDB, OPFS) vary by vendor and user settings; plan fallback strategies and educate users on clearing cache if needed.
  • WebGPU support is not universal across all browsers and devices; detect capability early and provide graceful degradation or server-side fallback.
  • Memory pressure in the browser may cause tab crashes if model size or concurrent operations exceed available VRAM; monitor and test on target hardware.
  • Worker thread offloading (Web Worker, Service Worker) is supported but adds complexity; assess whether UI performance gains justify architectural overhead.

When to avoid it — and what to weigh

  • Require Enterprise Model Support — If your use case demands proprietary models (GPT-4, Claude) or industry-specific fine-tuned variants, WebLLM's open-model-only approach may not meet requirements.
  • Need Maximum Model Accuracy/Scale — Browser-resident models are typically smaller (0.5B–8B parameters) due to memory constraints; applications requiring state-of-the-art 70B+ parameter models belong server-side.
  • Targeting Low-End Devices — WebGPU and sufficient VRAM are prerequisites; older browsers, mobile Safari, and devices with minimal GPU memory will face significant compatibility or performance limits.
  • Mission-Critical Compliance Requirements — If you require audited inference pipelines, formal security certifications, or guaranteed SLAs, unvetted browser-based inference may not satisfy compliance frameworks.

License & commercial use

Apache License 2.0 (Apache-2.0). This is a permissive OSI-approved license allowing commercial use, modification, and distribution, with minimal restrictions (retain copyright notices and license text).

Commercial use is permitted under Apache-2.0. No license restrictions prevent building commercial products or SaaS offerings on top of WebLLM. However, ensure you comply with licenses of any bundled models (e.g., Llama, Phi) which may have their own terms. Verify model licenses independently before commercial deployment.

DEV.co evaluation signals

Editorial assessment — not user reviews. Directional, with an explicit confidence level.

SignalAssessment
MaintenanceActive
DocumentationStrong
License clarityClear
Deployment complexityModerate
DEV.co fitGood
Assessment confidenceHigh
Security considerations

All inference occurs in-browser, eliminating data transmission to external servers and reducing typical client-server attack surface. However, consider: (1) browser XSS vulnerabilities can expose model outputs and user input; (2) model weights are downloaded and cached, requiring content-security verification; (3) no formal security audit details are published; (4) WebGPU is a nascent API with unknown long-term security implications. Perform threat modeling for your use case and validate model provenance.

Alternatives to consider

Ollama (Local Desktop)

Runs LLM inference locally on desktop/server with better performance and model flexibility, but requires separate infrastructure; better for non-web-bound applications.

Hugging Face Transformers.js

Browser-based ML library using WebAssembly and WebGPU; simpler to set up for smaller models but less optimized for LLM inference at scale compared to WebLLM.

OpenAI API / Anthropic API

Cloud-hosted inference with superior model capabilities (GPT-4, Claude) and reliability; trade privacy and latency for accuracy and compliance guarantees.

Software development agency

Build on web-llm with DEV.co software developers

WebLLM brings model inference directly to end-users with GPU acceleration and no server dependency. Explore examples, review browser compatibility, and assess model licensing for your use case.

Talk to DEV.co

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web-llm FAQ

Does WebLLM work on all browsers?
No. WebGPU support is required; Chrome/Edge support it, but Firefox and Safari support is limited or absent. Always detect WebGPU availability before attempting inference.
Can I use my own models with WebLLM?
Yes, via the 'Custom Models' feature. However, models must be compiled into MLC format using the MLC LLM toolchain, which requires compilation expertise and is not a plug-and-play process.
How much VRAM do I need?
Depends on the model. Smaller models (0.5B–1.5B) require 1–2 GB; mid-range (7B) require 4–8 GB. Browser memory limits and OS paging can reduce available capacity; test on target hardware.
Is this production-ready?
WebLLM is actively maintained and used in production by some projects, but it remains a relatively young technology. Thoroughly test browser/device coverage, model performance, and caching behavior before committing to production use.

Build it with a software development company

Pairing web-llm with the rest of your stack is where most ai frameworks projects stall. DEV.co is a software development agency that does the integration work — plus AI development when models are in scope.

Ready to Deploy Private AI in the Browser?

WebLLM brings model inference directly to end-users with GPU acceleration and no server dependency. Explore examples, review browser compatibility, and assess model licensing for your use case.