APIs and SDKs

Call Fireworks from custom agents, background runners, services, HTTP APIs, and SDKs

The same model ID works on every supported API.

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Compatible APIs

Choose the endpoint your SDK or client already uses:

API	Base URL to configure	Full endpoint	Typical clients
Anthropic Messages	https://api.fireworks.ai/inference	https://api.fireworks.ai/inference/v1/messages	Anthropic SDK, Claude Code
OpenAI Chat Completions	https://api.fireworks.ai/inference/v1	https://api.fireworks.ai/inference/v1/chat/completions	OpenAI SDK, Fireworks SDK, most gateways and harnesses
OpenAI Responses	https://api.fireworks.ai/inference/v1	https://api.fireworks.ai/inference/v1/responses	OpenAI SDK, Codex

Anthropic-style clients add /v1/messages to the base URL themselves, so their base URL ends at /inference.

For client setup, see OpenAI compatibility, Anthropic compatibility, or the Responses API.

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Call the API

Send your Fireworks key and any model ID:

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

auto works the same way on all three APIs. For Nexus Auto examples in cURL and the OpenAI, Anthropic, and Fireworks SDKs, see Nexus Auto.

For a Nexus Auto request, the response model field names the model that served the turn, such as glm-5p3 or claude-opus-5-5, not auto.

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Credentials

Credential	How to provide it	When
Fireworks API key (fw_...)	Authorization bearer token or X-Fireworks-Api-Key header	Every request; bills open-model traffic to your Fireworks account
Anthropic	Connect an Anthropic Provider Key if enabled, or send x-anthropic-api-key	You want auto to be able to use Anthropic models
OpenAI	Connect an OpenAI Provider Key if enabled, or send x-openai-api-key	You want auto to be able to use OpenAI models
Amazon Bedrock	Amazon Bedrock Provider Key	You want auto to use a model you mapped there. Usage bills to your AWS account.

In every SDK, api_key is the Fireworks key. Pass provider keys as extra headers, as shown in Nexus Auto.

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Limitations

• With US data residency, send Nexus Auto requests to us.api.fireworks.ai. Open-model turns run on US-only Serverless. Other regions must pin a model served in that region.
• Without an Anthropic or OpenAI credential, auto uses Fireworks open models.

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Troubleshooting

• 401: the Fireworks key is missing or invalid. Send a valid fw_... key with Authorization: Bearer or X-Fireworks-Api-Key.
• 404 Model id not found: the model ID is unknown, or the account can’t use this router. Check the model ID and your account’s access.
• 400 no_credential: the closed model you named has no provider key. Connect Provider Keys where available. For Anthropic or OpenAI, you can instead send the provider header.

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See also

• Nexus Auto
• Provider Keys
• Effort
• Routers load-balance traffic across your own Fireworks deployments. They are separate from auto, the Nexus Auto model ID.