Lightning-fast serving engine for AI models.
Easy. Flexible. Enterprise-scale.
LitServe is an easy-to-use, flexible serving engine for AI models built on FastAPI. It augments FastAPI with features like batching, streaming, and GPU autoscaling eliminate the need to rebuild a FastAPI server per model.
LitServe is at least 2x faster than plain FastAPI due to AI-specific multi-worker handling.
✅ (2x)+ faster serving ✅ Easy to use ✅ LLMs, non LLMs and more ✅ Bring your own model ✅ PyTorch/JAX/TF/... ✅ Built on FastAPI ✅ GPU autoscaling ✅ Batching, Streaming ✅ Self-host or ⚡️ managed ✅ Compound AI ✅ Integrate with vLLM and more
Install LitServe via pip (more options):
pip install litserveThis toy example with 2 models (AI compound system) shows LitServe's flexibility (see real examples):
# server.py
import litserve as ls
# (STEP 1) - DEFINE THE API (compound AI system)
class SimpleLitAPI(ls.LitAPI):
def setup(self, device):
# setup is called once at startup. Build a compound AI system (1+ models), connect DBs, load data, etc...
self.model1 = lambda x: x**2
self.model2 = lambda x: x**3
def decode_request(self, request):
# Convert the request payload to model input.
return request["input"]
def predict(self, x):
# Easily build compound systems. Run inference and return the output.
squared = self.model1(x)
cubed = self.model2(x)
output = squared + cubed
return {"output": output}
def encode_response(self, output):
# Convert the model output to a response payload.
return {"output": output}
# (STEP 2) - START THE SERVER
if __name__ == "__main__":
# scale with advanced features (batching, GPUs, etc...)
server = ls.LitServer(SimpleLitAPI(), accelerator="auto", max_batch_size=1)
server.run(port=8000)Now run the server via the command-line
python server.pyRun the auto-generated test client:
python client.py Or use this terminal command:
curl -X POST http://127.0.0.1:8000/predict -H "Content-Type: application/json" -d '{"input": 4.0}'LitServe isn’t just for LLMs like vLLM or Ollama; it serves any AI model with full control over internals (learn more).
For easy LLM serving, integrate vLLM with LitServe, or use LitGPT (built on LitServe).
litgpt serve microsoft/phi-2
- LitAPI lets you easily build complex AI systems with one or more models (docs).
- Use the setup method for one-time tasks like connecting models, DBs, and loading data (docs).
- LitServer handles optimizations like batching, GPU autoscaling, streaming, etc... (docs).
- Self host on your own machines or use Lightning Studios for a fully managed deployment (learn more).
Learn how to make this server 200x faster.
Use LitServe to deploy any model or AI service: (Compound AI, Gen AI, classic ML, embeddings, LLMs, vision, audio, etc...)
LitServe_Overview.mp4
Toy model: Hello world LLMs: Llama 3.2, LLM Proxy server, Agent with tool use RAG: vLLM RAG (Llama 3.2), RAG API (LlamaIndex) NLP: Hugging face, BERT, Text embedding API Multimodal: OpenAI Clip, MiniCPM, Phi-3.5 Vision Instruct, Qwen2-VL, Pixtral Audio: Whisper, AudioCraft, StableAudio, Noise cancellation (DeepFilterNet) Vision: Stable diffusion 2, AuraFlow, Flux, Image Super Resolution (Aura SR), Background Removal, Control Stable Diffusion (ControlNet) Speech: Text-speech (XTTS V2), Parler-TTS Classical ML: Random forest, XGBoost Miscellaneous: Media conversion API (ffmpeg), PyTorch + TensorFlow in one API
Browse 100+ community-built templates
State-of-the-art features:
✅ (2x)+ faster than plain FastAPI
✅ Bring your own model
✅ Build compound systems (1+ models)
✅ GPU autoscaling
✅ Batching
✅ Streaming
✅ Worker autoscaling
✅ Self-host on your machines
✅ Host fully managed on Lightning AI
✅ Serve all models: (LLMs, vision, etc.)
✅ Scale to zero (serverless)
✅ Supports PyTorch, JAX, TF, etc...
✅ OpenAPI compliant
✅ Open AI compatibility
✅ Authentication
✅ Dockerization
Note: We prioritize scalable, enterprise-level features over hype.
LitServe is designed for AI workloads. Specialized multi-worker handling delivers a minimum 2x speedup over FastAPI.
Additional features like batching and GPU autoscaling can drive performance well beyond 2x, scaling efficiently to handle more simultaneous requests than FastAPI and TorchServe.
Reproduce the full benchmarks here (higher is better).
These results are for image and text classification ML tasks. The performance relationships hold for other ML tasks (embedding, LLM serving, audio, segmentation, object detection, summarization etc...).
💡 Note on LLM serving: For high-performance LLM serving (like Ollama/vLLM), integrate vLLM with LitServe, use LitGPT, or build your custom vLLM-like server with LitServe. Optimizations like kv-caching, which can be done with LitServe, are needed to maximize LLM performance.
LitServe can be hosted independently on your own machines or fully managed via Lightning Studios.
Self-hosting is ideal for hackers, students, and DIY developers, while fully managed hosting is ideal for enterprise developers needing easy autoscaling, security, release management, and 99.995% uptime and observability.
| Feature | Self Managed | Fully Managed on Studios |
|---|---|---|
| Deployment | ✅ Do it yourself deployment | ✅ One-button cloud deploy |
| Load balancing | ❌ | ✅ |
| Autoscaling | ❌ | ✅ |
| Scale to zero | ❌ | ✅ |
| Multi-machine inference | ❌ | ✅ |
| Authentication | ❌ | ✅ |
| Own VPC | ❌ | ✅ |
| AWS, GCP | ❌ | ✅ |
| Use your own cloud commits | ❌ | ✅ |
LitServe is a community project accepting contributions - Let's make the world's most advanced AI inference engine.