Migrate to Fireworks

Fireworks accepts OpenAI, Anthropic, and NVIDIA NIM or vLLM requests, so your SDK and app code stay as they are. You change three values: the base URL, the API key, and the model name.

Your app uses	Start here
OpenAI SDKs or the OpenAI API format	OpenAI compatibility
Anthropic SDKs or the Messages API	Anthropic compatibility
NVIDIA NIM or vLLM, including their extra request fields	NIM compatibility

How to migrate

Create an API key

Create a key in the Fireworks dashboard and export it:

export FIREWORKS_API_KEY="<YOUR_FIREWORKS_API_KEY>"

Point your client at Fireworks

Pick your API in the tabs below. In your existing code, update the highlighted lines: the base URL, API key, and model name. The rest of your code stays the same.

import os
from openai import OpenAI

client = OpenAI(
    base_url="https://api.fireworks.ai/inference/v1",
    api_key=os.environ["FIREWORKS_API_KEY"],
)

response = client.chat.completions.create(
    model="accounts/fireworks/models/kimi-k3",
    messages=[{"role": "user", "content": "Say hello in one word."}],
)
print(response.choices[0].message.content)

import os
import anthropic

client = anthropic.Anthropic(
    base_url="https://api.fireworks.ai/inference",  # no /v1
    api_key=os.environ["FIREWORKS_API_KEY"],
)

response = client.messages.create(
    model="accounts/fireworks/models/kimi-k3",
    max_tokens=256,
    messages=[{"role": "user", "content": "Say hello in one word."}],
)
print(response.content[0].text)

import os
from openai import OpenAI

client = OpenAI(
    base_url="https://api.fireworks.ai/inference/v1",
    api_key=os.environ["FIREWORKS_API_KEY"],
)

response = client.chat.completions.create(
    model="accounts/fireworks/models/kimi-k3",
    messages=[{"role": "user", "content": "Say hello in one word."}],
    # NIM-style extras still work. Fireworks maps this to reasoning_effort="none".
    extra_body={"chat_template_kwargs": {"enable_thinking": False}},
)
print(response.choices[0].message.content)

curl https://api.fireworks.ai/inference/v1/chat/completions \
  -H "Authorization: Bearer $FIREWORKS_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "accounts/fireworks/models/kimi-k3",
    "messages": [{"role": "user", "content": "Say hello in one word."}]
  }'

# OpenAI SDKs
export OPENAI_BASE_URL="https://api.fireworks.ai/inference/v1"
export OPENAI_API_KEY="$FIREWORKS_API_KEY"

# Anthropic SDKs, Claude Code, and the Claude Agent SDK
export ANTHROPIC_BASE_URL="https://api.fireworks.ai/inference"  # no /v1
export ANTHROPIC_AUTH_TOKEN="$FIREWORKS_API_KEY"

Pick a replacement model

Fireworks model names use the format accounts/fireworks/models/<model>. To find the closest match for the model you use today, see Compare models or browse the model catalog.

Check what behaves differently

Most requests work unchanged. These are the differences that most often affect a migration:

OpenAI: when the prompt plus max_tokens exceeds the context window, Fireworks lowers max_tokens instead of returning an error. Set context_length_exceeded_behavior to error to match OpenAI. Streaming responses include usage in the final chunk.
Anthropic: Fireworks does not run server-side tools such as web search, code execution, memory, or web fetch. Declare them as client-side tools and run them yourself. The anthropic-version header is ignored.
NIM and vLLM: Fireworks maps the thinking keys in chat_template_kwargs to reasoning_effort and drops any other keys in that object.

Each guide lists every supported field: OpenAI, Anthropic, NIM.

Test before you switch traffic

Send one request first. Then run the prompts, tool calls, and streaming paths your app depends on, and compare output quality and latency before you move production traffic.

Get started

Inference

Nexus

Training

Account & security

Resources

How to migrate

Next steps

Get an API key

Compare models