Alexsander HamirandGitHub eb5031da1e [Perf] Fix bottlenecks degrading realtime endpoint performance (#16670)
* Cache realtime websocket request body

Move the realtime request payload builder out of the websocket handler and wrap it with an LRU cache so repeated connections reuse the same bytes object. This keeps the JSON formatting cost down while bounding memory usage.

* Optimize realtime websocket caching

Refactored /v1/realtime to use cached helpers for both the JSON body and query params, introduced a reusable request-scope template, and optimized header handling to avoid redundant work.

* Refine realtime websocket header handling

* Reuse websocket scope headers in auth

* Refactor realtime request body helper

Move the realtime request body formatter into proxy common utils so it can be reused across modules. Reuse it in the websocket auth flow to share LRU caching and avoid ad hoc byte builders.

* fix: revert to old pattern

The old pattern was necessary, we can just return the optimized function instead.

* Reuse SSL context for realtime

Create a shared SSLContext for OpenAI realtime websocket dials and pass it into websockets.connect so we stop re-reading verify paths on every session.

* feat: reuse shared TLS context for realtime websockets

- add `SHARED_REALTIME_SSL_CONTEXT` helper so all realtime websocket clients share the same TLS settings
- wire the shared context into OpenAI, Azure, custom HTTPX handlers, and realtime health checks
- update realtime tests to assert that the expected SSL context is passed to `websockets.connect`

This keeps TLS configuration consistent and avoids recreating SSL contexts per connection.

* Reuse HTTP SSL context for realtime

Remove the standalone realtime SSL helper, expose a shared context directly from the HTTP handler, and point all realtime websocket clients and tests to it. Add the websocket header comparison tool.

* Lazy-load shared realtime SSL context

Fix circular imports introduced by eagerly instantiating the shared TLS context. Make the HTTP handler lazily create the context and have realtime clients/tests fetch it on demand, keeping configuration consistent without breaking startup.

* add: unit test for realtime LRU caches

* fix: merge conflict with imports
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🚅 LiteLLM

Deploy to Render Deploy on Railway

Call all LLM APIs using the OpenAI format [Bedrock, Huggingface, VertexAI, TogetherAI, Azure, OpenAI, Groq etc.]

LiteLLM Proxy Server (LLM Gateway) | Hosted Proxy (Preview) | Enterprise Tier

PyPI Version Y Combinator W23 Whatsapp Discord Slack

LiteLLM manages:

  • Translate inputs to provider's completion, embedding, and image_generation endpoints
  • Consistent output, text responses will always be available at ['choices'][0]['message']['content']
  • Retry/fallback logic across multiple deployments (e.g. Azure/OpenAI) - Router
  • Set Budgets & Rate limits per project, api key, model LiteLLM Proxy Server (LLM Gateway)

LiteLLM Performance: 8ms P95 latency at 1k RPS (See benchmarks here)

Jump to LiteLLM Proxy (LLM Gateway) Docs
Jump to Supported LLM Providers

🚨 Stable Release: Use docker images with the -stable tag. These have undergone 12 hour load tests, before being published. More information about the release cycle here

Support for more providers. Missing a provider or LLM Platform, raise a feature request.

Usage (Docs)

Important

LiteLLM v1.0.0 now requires openai>=1.0.0. Migration guide here LiteLLM v1.40.14+ now requires pydantic>=2.0.0. No changes required.

Open In Colab
pip install litellm
from litellm import completion
import os

## set ENV variables
os.environ["OPENAI_API_KEY"] = "your-openai-key"
os.environ["ANTHROPIC_API_KEY"] = "your-anthropic-key"

messages = [{ "content": "Hello, how are you?","role": "user"}]

# openai call
response = completion(model="openai/gpt-4o", messages=messages)

# anthropic call
response = completion(model="anthropic/claude-sonnet-4-20250514", messages=messages)
print(response)

Response (OpenAI Format)

{
    "id": "chatcmpl-1214900a-6cdd-4148-b663-b5e2f642b4de",
    "created": 1751494488,
    "model": "claude-sonnet-4-20250514",
    "object": "chat.completion",
    "system_fingerprint": null,
    "choices": [
        {
            "finish_reason": "stop",
            "index": 0,
            "message": {
                "content": "Hello! I'm doing well, thank you for asking. I'm here and ready to help with whatever you'd like to discuss or work on. How are you doing today?",
                "role": "assistant",
                "tool_calls": null,
                "function_call": null
            }
        }
    ],
    "usage": {
        "completion_tokens": 39,
        "prompt_tokens": 13,
        "total_tokens": 52,
        "completion_tokens_details": null,
        "prompt_tokens_details": {
            "audio_tokens": null,
            "cached_tokens": 0
        },
        "cache_creation_input_tokens": 0,
        "cache_read_input_tokens": 0
    }
}

Call any model supported by a provider, with model=<provider_name>/<model_name>. There might be provider-specific details here, so refer to provider docs for more information

Async (Docs)

from litellm import acompletion
import asyncio

async def test_get_response():
    user_message = "Hello, how are you?"
    messages = [{"content": user_message, "role": "user"}]
    response = await acompletion(model="openai/gpt-4o", messages=messages)
    return response

response = asyncio.run(test_get_response())
print(response)

Streaming (Docs)

LiteLLM supports streaming the model response back, pass stream=True to get a streaming iterator in response. Streaming is supported for all models (Bedrock, Huggingface, TogetherAI, Azure, OpenAI, etc.)

from litellm import completion

messages = [{"content": "Hello, how are you?", "role": "user"}]

# gpt-4o
response = completion(model="openai/gpt-4o", messages=messages, stream=True)
for part in response:
    print(part.choices[0].delta.content or "")

# claude sonnet 4
response = completion('anthropic/claude-sonnet-4-20250514', messages, stream=True)
for part in response:
    print(part)

Response chunk (OpenAI Format)

{
    "id": "chatcmpl-fe575c37-5004-4926-ae5e-bfbc31f356ca",
    "created": 1751494808,
    "model": "claude-sonnet-4-20250514",
    "object": "chat.completion.chunk",
    "system_fingerprint": null,
    "choices": [
        {
            "finish_reason": null,
            "index": 0,
            "delta": {
                "provider_specific_fields": null,
                "content": "Hello",
                "role": "assistant",
                "function_call": null,
                "tool_calls": null,
                "audio": null
            },
            "logprobs": null
        }
    ],
    "provider_specific_fields": null,
    "stream_options": null,
    "citations": null
}

Logging Observability (Docs)

LiteLLM exposes pre defined callbacks to send data to Lunary, MLflow, Langfuse, DynamoDB, s3 Buckets, Helicone, Promptlayer, Traceloop, Athina, Slack

from litellm import completion

## set env variables for logging tools (when using MLflow, no API key set up is required)
os.environ["LUNARY_PUBLIC_KEY"] = "your-lunary-public-key"
os.environ["HELICONE_API_KEY"] = "your-helicone-auth-key"
os.environ["LANGFUSE_PUBLIC_KEY"] = ""
os.environ["LANGFUSE_SECRET_KEY"] = ""
os.environ["ATHINA_API_KEY"] = "your-athina-api-key"

os.environ["OPENAI_API_KEY"] = "your-openai-key"

# set callbacks
litellm.success_callback = ["lunary", "mlflow", "langfuse", "athina", "helicone"] # log input/output to lunary, langfuse, supabase, athina, helicone etc

#openai call
response = completion(model="openai/gpt-4o", messages=[{"role": "user", "content": "Hi 👋 - i'm openai"}])

LiteLLM Proxy Server (LLM Gateway) - (Docs)

Track spend + Load Balance across multiple projects

Hosted Proxy (Preview)

The proxy provides:

  1. Hooks for auth
  2. Hooks for logging
  3. Cost tracking
  4. Rate Limiting

📖 Proxy Endpoints - Swagger Docs

Quick Start Proxy - CLI

pip install 'litellm[proxy]'

Step 1: Start litellm proxy

$ litellm --model huggingface/bigcode/starcoder

#INFO: Proxy running on http://0.0.0.0:4000

Step 2: Make ChatCompletions Request to Proxy

Important

💡 Use LiteLLM Proxy with Langchain (Python, JS), OpenAI SDK (Python, JS) Anthropic SDK, Mistral SDK, LlamaIndex, Instructor, Curl

import openai # openai v1.0.0+
client = openai.OpenAI(api_key="anything",base_url="http://0.0.0.0:4000") # set proxy to base_url
# request sent to model set on litellm proxy, `litellm --model`
response = client.chat.completions.create(model="gpt-3.5-turbo", messages = [
    {
        "role": "user",
        "content": "this is a test request, write a short poem"
    }
])

print(response)

Proxy Key Management (Docs)

Connect the proxy with a Postgres DB to create proxy keys

# Get the code
git clone https://github.com/BerriAI/litellm

# Go to folder
cd litellm

# Add the master key - you can change this after setup
echo 'LITELLM_MASTER_KEY="sk-1234"' > .env

# Add the litellm salt key - you cannot change this after adding a model
# It is used to encrypt / decrypt your LLM API Key credentials
# We recommend - https://1password.com/password-generator/
# password generator to get a random hash for litellm salt key
echo 'LITELLM_SALT_KEY="sk-1234"' >> .env

source .env

# Start
docker compose up

UI on /ui on your proxy server ui_3

Set budgets and rate limits across multiple projects POST /key/generate

Request

curl 'http://0.0.0.0:4000/key/generate' \
--header 'Authorization: Bearer sk-1234' \
--header 'Content-Type: application/json' \
--data-raw '{"models": ["gpt-3.5-turbo", "gpt-4", "claude-2"], "duration": "20m","metadata": {"user": "ishaan@berri.ai", "team": "core-infra"}}'

Expected Response

{
    "key": "sk-kdEXbIqZRwEeEiHwdg7sFA", # Bearer token
    "expires": "2023-11-19T01:38:25.838000+00:00" # datetime object
}

Supported Providers (Website Supported Models | Docs)

Provider /chat/completions /messages /responses /embeddings /image/generations /audio/transcriptions /audio/speech /moderations /batches /rerank
AI/ML API (aiml)
AI21 (ai21)
AI21 Chat (ai21_chat)
Aleph Alpha
Anthropic (anthropic)
Anthropic Text (anthropic_text)
Anyscale
AssemblyAI (assemblyai)
Auto Router (auto_router)
AWS - Bedrock (bedrock)
AWS - Sagemaker (sagemaker)
Azure (azure)
Azure AI (azure_ai)
Azure Text (azure_text)
Baseten (baseten)
Bytez (bytez)
Cerebras (cerebras)
Clarifai (clarifai)
Cloudflare AI Workers (cloudflare)
Codestral (codestral)
Cohere (cohere)
Cohere Chat (cohere_chat)
CometAPI (cometapi)
CompactifAI (compactifai)
Custom (custom)
Custom OpenAI (custom_openai)
Dashscope (dashscope)
Databricks (databricks)
DataRobot (datarobot)
Deepgram (deepgram)
DeepInfra (deepinfra)
Deepseek (deepseek)
ElevenLabs (elevenlabs)
Empower (empower)
Fal AI (fal_ai)
Featherless AI (featherless_ai)
Fireworks AI (fireworks_ai)
FriendliAI (friendliai)
Galadriel (galadriel)
GitHub Copilot (github_copilot)
GitHub Models (github)
Google - PaLM
Google - Vertex AI (vertex_ai)
Google AI Studio - Gemini (gemini)
GradientAI (gradient_ai)
Groq AI (groq)
Heroku (heroku)
Hosted VLLM (hosted_vllm)
Huggingface (huggingface)
Hyperbolic (hyperbolic)
IBM - Watsonx.ai (watsonx)
Infinity (infinity)
Jina AI (jina_ai)
Lambda AI (lambda_ai)
Lemonade (lemonade)
LiteLLM Proxy (litellm_proxy)
Llamafile (llamafile)
LM Studio (lm_studio)
Maritalk (maritalk)
Meta - Llama API (meta_llama)
Mistral AI API (mistral)
Moonshot (moonshot)
Morph (morph)
Nebius AI Studio (nebius)
NLP Cloud (nlp_cloud)
Novita AI (novita)
Nscale (nscale)
Nvidia NIM (nvidia_nim)
OCI (oci)
Ollama (ollama)
Ollama Chat (ollama_chat)
Oobabooga (oobabooga)
OpenAI (openai)
OpenAI-like (openai_like)
OpenRouter (openrouter)
OVHCloud AI Endpoints (ovhcloud)
Perplexity AI (perplexity)
Petals (petals)
Predibase (predibase)
Recraft (recraft)
Replicate (replicate)
Sagemaker Chat (sagemaker_chat)
Sambanova (sambanova)
Snowflake (snowflake)
Text Completion Codestral (text-completion-codestral)
Text Completion OpenAI (text-completion-openai)
Together AI (together_ai)
Topaz (topaz)
Triton (triton)
V0 (v0)
Vercel AI Gateway (vercel_ai_gateway)
VLLM (vllm)
Volcengine (volcengine)
Voyage AI (voyage)
WandB Inference (wandb)
Watsonx Text (watsonx_text)
xAI (xai)
Xinference (xinference)

Read the Docs

Run in Developer mode

Services

  1. Setup .env file in root
  2. Run dependant services docker-compose up db prometheus

Backend

  1. (In root) create virtual environment python -m venv .venv
  2. Activate virtual environment source .venv/bin/activate
  3. Install dependencies pip install -e ".[all]"
  4. Start proxy backend python litellm/proxy_cli.py

Frontend

  1. Navigate to ui/litellm-dashboard
  2. Install dependencies npm install
  3. Run npm run dev to start the dashboard

Enterprise

For companies that need better security, user management and professional support

Talk to founders

This covers:

  • Features under the LiteLLM Commercial License:
  • Feature Prioritization
  • Custom Integrations
  • Professional Support - Dedicated discord + slack
  • Custom SLAs
  • Secure access with Single Sign-On

Contributing

We welcome contributions to LiteLLM! Whether you're fixing bugs, adding features, or improving documentation, we appreciate your help.

Quick Start for Contributors

This requires poetry to be installed.

git clone https://github.com/BerriAI/litellm.git
cd litellm
make install-dev    # Install development dependencies
make format         # Format your code
make lint           # Run all linting checks
make test-unit      # Run unit tests
make format-check   # Check formatting only

For detailed contributing guidelines, see CONTRIBUTING.md.

Code Quality / Linting

LiteLLM follows the Google Python Style Guide.

Our automated checks include:

  • Black for code formatting
  • Ruff for linting and code quality
  • MyPy for type checking
  • Circular import detection
  • Import safety checks

All these checks must pass before your PR can be merged.

Support / talk with founders

Why did we build this

  • Need for simplicity: Our code started to get extremely complicated managing & translating calls between Azure, OpenAI and Cohere.

Contributors

S
Description
Python SDK, Proxy Server (AI Gateway) to call 100+ LLM APIs in OpenAI (or native) format, with cost tracking, guardrails, loadbalancing and logging. [Bedrock, Azure, OpenAI, VertexAI, Cohere, Anthropic, Sagemaker, HuggingFace, VLLM, NVIDIA NIM]
Readme MIT
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TypeScript 12.2%
JavaScript 5.9%
HTML 0.5%
HCL 0.2%