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LiteLLM - Getting Started

https://github.com/BerriAI/litellm

Call 100+ LLMs using the OpenAI Input/Output Format

• 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
• Track spend & set budgets per project LiteLLM Proxy Server

How to use LiteLLM

You can use litellm through either:

1. LiteLLM Proxy Server - Server (LLM Gateway) to call 100+ LLMs, load balance, cost tracking across projects
2. LiteLLM python SDK - Python Client to call 100+ LLMs, load balance, cost tracking

When to use LiteLLM Proxy Server (LLM Gateway)

:::tip

Use LiteLLM Proxy Server if you want a central service (LLM Gateway) to access multiple LLMs

Typically used by Gen AI Enablement / ML PLatform Teams

:::

• LiteLLM Proxy gives you a unified interface to access multiple LLMs (100+ LLMs)
• Track LLM Usage and setup guardrails
• Customize Logging, Guardrails, Caching per project

When to use LiteLLM Python SDK

:::tip

Use LiteLLM Python SDK if you want to use LiteLLM in your python code

Typically used by developers building llm projects

:::

• LiteLLM SDK gives you a unified interface to access multiple LLMs (100+ LLMs)
• Retry/fallback logic across multiple deployments (e.g. Azure/OpenAI) - Router

LiteLLM Python SDK

Basic usage

pip install litellm

from litellm import completion
import os

## set ENV variables
os.environ["OPENAI_API_KEY"] = "your-api-key"

response = completion(
  model="openai/gpt-4o",
  messages=[{ "content": "Hello, how are you?","role": "user"}]
)

from litellm import completion
import os

## set ENV variables
os.environ["ANTHROPIC_API_KEY"] = "your-api-key"

response = completion(
  model="anthropic/claude-3-sonnet-20240229",
  messages=[{ "content": "Hello, how are you?","role": "user"}]
)

from litellm import completion
import os

## set ENV variables
os.environ["XAI_API_KEY"] = "your-api-key"

response = completion(
  model="xai/grok-2-latest",
  messages=[{ "content": "Hello, how are you?","role": "user"}]
)

from litellm import completion
import os

# auth: run 'gcloud auth application-default'
os.environ["VERTEXAI_PROJECT"] = "hardy-device-386718"
os.environ["VERTEXAI_LOCATION"] = "us-central1"

response = completion(
  model="vertex_ai/gemini-1.5-pro",
  messages=[{ "content": "Hello, how are you?","role": "user"}]
)

from litellm import completion
import os

## set ENV variables
os.environ["NVIDIA_NIM_API_KEY"] = "nvidia_api_key"
os.environ["NVIDIA_NIM_API_BASE"] = "nvidia_nim_endpoint_url"

response = completion(
  model="nvidia_nim/<model_name>",
  messages=[{ "content": "Hello, how are you?","role": "user"}]
)

from litellm import completion
import os

os.environ["HUGGINGFACE_API_KEY"] = "huggingface_api_key"

# e.g. Call 'WizardLM/WizardCoder-Python-34B-V1.0' hosted on HF Inference endpoints
response = completion(
  model="huggingface/WizardLM/WizardCoder-Python-34B-V1.0",
  messages=[{ "content": "Hello, how are you?","role": "user"}],
  api_base="https://my-endpoint.huggingface.cloud"
)

print(response)

from litellm import completion
import os

## set ENV variables
os.environ["AZURE_API_KEY"] = ""
os.environ["AZURE_API_BASE"] = ""
os.environ["AZURE_API_VERSION"] = ""

# azure call
response = completion(
  "azure/<your_deployment_name>",
  messages = [{ "content": "Hello, how are you?","role": "user"}]
)

from litellm import completion

response = completion(
            model="ollama/llama2",
            messages = [{ "content": "Hello, how are you?","role": "user"}],
            api_base="http://localhost:11434"
)

from litellm import completion
import os

## set ENV variables
os.environ["OPENROUTER_API_KEY"] = "openrouter_api_key"

response = completion(
  model="openrouter/google/palm-2-chat-bison",
  messages = [{ "content": "Hello, how are you?","role": "user"}],
)

from litellm import completion
import os

## set ENV variables. Visit https://novita.ai/settings/key-management to get your API key
os.environ["NOVITA_API_KEY"] = "novita-api-key"

response = completion(
  model="novita/deepseek/deepseek-r1",
  messages=[{ "content": "Hello, how are you?","role": "user"}]
)

from litellm import completion
import os

## set ENV variables. Visit https://vercel.com/docs/ai-gateway#using-the-ai-gateway-with-an-api-key for insturctions on obtaining a key
os.environ["VERCEL_AI_GATEWAY_API_KEY"] = "your-vercel-api-key"

response = completion(
  model="vercel_ai_gateway/openai/gpt-4o",
  messages=[{ "content": "Hello, how are you?","role": "user"}]
)

Response Format (OpenAI Format)

{
    "id": "chatcmpl-565d891b-a42e-4c39-8d14-82a1f5208885",
    "created": 1734366691,
    "model": "gpt-4o-2024-08-06",
    "object": "chat.completion",
    "system_fingerprint": null,
    "choices": [
        {
            "finish_reason": "stop",
            "index": 0,
            "message": {
                "content": "Hello! As an AI language model, I don't have feelings, but I'm operating properly and ready to assist you with any questions or tasks you may have. How can I help you today?",
                "role": "assistant",
                "tool_calls": null,
                "function_call": null
            }
        }
    ],
    "usage": {
        "completion_tokens": 43,
        "prompt_tokens": 13,
        "total_tokens": 56,
        "completion_tokens_details": null,
        "prompt_tokens_details": {
            "audio_tokens": null,
            "cached_tokens": 0
        },
        "cache_creation_input_tokens": 0,
        "cache_read_input_tokens": 0
    }
}

Streaming

Set stream=True in the completion args.

from litellm import completion
import os

## set ENV variables
os.environ["OPENAI_API_KEY"] = "your-api-key"

response = completion(
  model="openai/gpt-4o",
  messages=[{ "content": "Hello, how are you?","role": "user"}],
  stream=True,
)

from litellm import completion
import os

## set ENV variables
os.environ["ANTHROPIC_API_KEY"] = "your-api-key"

response = completion(
  model="anthropic/claude-3-sonnet-20240229",
  messages=[{ "content": "Hello, how are you?","role": "user"}],
  stream=True,
)

from litellm import completion
import os

## set ENV variables
os.environ["XAI_API_KEY"] = "your-api-key"

response = completion(
  model="xai/grok-2-latest",
  messages=[{ "content": "Hello, how are you?","role": "user"}],
  stream=True,
)

from litellm import completion
import os

# auth: run 'gcloud auth application-default'
os.environ["VERTEX_PROJECT"] = "hardy-device-386718"
os.environ["VERTEX_LOCATION"] = "us-central1"

response = completion(
  model="vertex_ai/gemini-1.5-pro",
  messages=[{ "content": "Hello, how are you?","role": "user"}],
  stream=True,
)

from litellm import completion
import os

## set ENV variables
os.environ["NVIDIA_NIM_API_KEY"] = "nvidia_api_key"
os.environ["NVIDIA_NIM_API_BASE"] = "nvidia_nim_endpoint_url"

response = completion(
  model="nvidia_nim/<model_name>",
  messages=[{ "content": "Hello, how are you?","role": "user"}]
  stream=True,
)

from litellm import completion
import os

os.environ["HUGGINGFACE_API_KEY"] = "huggingface_api_key"

# e.g. Call 'WizardLM/WizardCoder-Python-34B-V1.0' hosted on HF Inference endpoints
response = completion(
  model="huggingface/WizardLM/WizardCoder-Python-34B-V1.0",
  messages=[{ "content": "Hello, how are you?","role": "user"}],
  api_base="https://my-endpoint.huggingface.cloud",
  stream=True,
)

print(response)

from litellm import completion
import os

## set ENV variables
os.environ["AZURE_API_KEY"] = ""
os.environ["AZURE_API_BASE"] = ""
os.environ["AZURE_API_VERSION"] = ""

# azure call
response = completion(
  "azure/<your_deployment_name>",
  messages = [{ "content": "Hello, how are you?","role": "user"}],
  stream=True,
)

from litellm import completion

response = completion(
            model="ollama/llama2",
            messages = [{ "content": "Hello, how are you?","role": "user"}],
            api_base="http://localhost:11434",
            stream=True,
)

from litellm import completion
import os

## set ENV variables
os.environ["OPENROUTER_API_KEY"] = "openrouter_api_key"

response = completion(
  model="openrouter/google/palm-2-chat-bison",
  messages = [{ "content": "Hello, how are you?","role": "user"}],
  stream=True,
)

from litellm import completion
import os

## set ENV variables. Visit https://novita.ai/settings/key-management to get your API key
os.environ["NOVITA_API_KEY"] = "novita_api_key"

response = completion(
  model="novita/deepseek/deepseek-r1",
  messages = [{ "content": "Hello, how are you?","role": "user"}],
  stream=True,
)

from litellm import completion
import os

## set ENV variables. Visit https://vercel.com/docs/ai-gateway#using-the-ai-gateway-with-an-api-key for insturctions on obtaining a key
os.environ["VERCEL_AI_GATEWAY_API_KEY"] = "your-vercel-api-key"

response = completion(
  model="vercel_ai_gateway/openai/gpt-4o",
  messages = [{ "content": "Hello, how are you?","role": "user"}],
  stream=True,
)

Streaming Response Format (OpenAI Format)

{
    "id": "chatcmpl-2be06597-eb60-4c70-9ec5-8cd2ab1b4697",
    "created": 1734366925,
    "model": "claude-3-sonnet-20240229",
    "object": "chat.completion.chunk",
    "system_fingerprint": null,
    "choices": [
        {
            "finish_reason": null,
            "index": 0,
            "delta": {
                "content": "Hello",
                "role": "assistant",
                "function_call": null,
                "tool_calls": null,
                "audio": null
            },
            "logprobs": null
        }
    ]
}

Exception handling

LiteLLM maps exceptions across all supported providers to the OpenAI exceptions. All our exceptions inherit from OpenAI's exception types, so any error-handling you have for that, should work out of the box with LiteLLM.

from openai.error import OpenAIError
from litellm import completion

os.environ["ANTHROPIC_API_KEY"] = "bad-key"
try:
    # some code
    completion(model="claude-instant-1", messages=[{"role": "user", "content": "Hey, how's it going?"}])
except OpenAIError as e:
    print(e)

See How LiteLLM Transforms Your Requests

Want to understand how LiteLLM parses and normalizes your LLM API requests? Use the /utils/transform_request endpoint to see exactly how your request is transformed internally.

You can try it out now directly on our Demo App! Go to the LiteLLM API docs for transform_request

LiteLLM will show you the normalized, provider-agnostic version of your request. This is useful for debugging, learning, and understanding how LiteLLM handles different providers and options.

Logging Observability - Log LLM Input/Output (Docs)

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

from litellm import completion

## set env variables for logging tools (API key set up is not required when using MLflow)
os.environ["LUNARY_PUBLIC_KEY"] = "your-lunary-public-key" # get your public key at https://app.lunary.ai/settings
os.environ["HELICONE_API_KEY"] = "your-helicone-key"
os.environ["LANGFUSE_PUBLIC_KEY"] = ""
os.environ["LANGFUSE_SECRET_KEY"] = ""

os.environ["OPENAI_API_KEY"]

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

#openai call
response = completion(model="gpt-3.5-turbo", messages=[{"role": "user", "content": "Hi 👋 - i'm openai"}])

Track Costs, Usage, Latency for streaming

Use a callback function for this - more info on custom callbacks: https://docs.litellm.ai/docs/observability/custom_callback

import litellm

# track_cost_callback
def track_cost_callback(
    kwargs,                 # kwargs to completion
    completion_response,    # response from completion
    start_time, end_time    # start/end time
):
    try:
      response_cost = kwargs.get("response_cost", 0)
      print("streaming response_cost", response_cost)
    except:
        pass
# set callback
litellm.success_callback = [track_cost_callback] # set custom callback function

# litellm.completion() call
response = completion(
    model="gpt-3.5-turbo",
    messages=[
        {
            "role": "user",
            "content": "Hi 👋 - i'm openai"
        }
    ],
    stream=True
)

LiteLLM Proxy Server (LLM Gateway)

Track spend across multiple projects/people

The proxy provides:

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

📖 Proxy Endpoints - Swagger Docs

Go here for a complete tutorial with keys + rate limits - here

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 1. CREATE config.yaml

Example litellm_config.yaml

model_list:
  - model_name: gpt-3.5-turbo
    litellm_params:
      model: azure/<your-azure-model-deployment>
      api_base: os.environ/AZURE_API_BASE # runs os.getenv("AZURE_API_BASE")
      api_key: os.environ/AZURE_API_KEY # runs os.getenv("AZURE_API_KEY")
      api_version: "2023-07-01-preview"

Step 2. RUN Docker Image

docker run \
    -v $(pwd)/litellm_config.yaml:/app/config.yaml \
    -e AZURE_API_KEY=d6*********** \
    -e AZURE_API_BASE=https://openai-***********/ \
    -p 4000:4000 \
    ghcr.io/berriai/litellm:main-latest \
    --config /app/config.yaml --detailed_debug

Step 2: Make ChatCompletions Request to Proxy

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)

More details

• exception mapping
• retries + model fallbacks for completion()
• proxy virtual keys & spend management
• E2E Tutorial for LiteLLM Proxy Server