APIs and SDKs

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

Call Fireworks from custom agents, background jobs, or services with curl, the OpenAI SDK, the Anthropic SDK, or the Fireworks SDK. Send requests to https://api.fireworks.ai/inference and use the same model ID across each supported API.

Compatible APIs

Choose the endpoint your SDK or client already uses:

API format	Endpoint	Typical clients
Chat completions (OpenAI-style)	POST /v1/chat/completions	OpenAI SDK, most LLM gateways
Messages (Anthropic-style)	POST /v1/messages	Anthropic SDK
Responses (OpenAI-style)	POST /v1/responses	OpenAI Responses API clients

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

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."}]
  }'

Router IDs such as firerouter/opus work the same way on all three APIs.

FireRouter examples for every API and SDK

cURL, OpenAI, Anthropic, and Fireworks SDK examples for Chat Completions, Responses, and Messages, with provider-key headers.

Read the serving model

For a router request, the response model field names the model that served the turn, such as glm-5p3 or claude-opus-5-5, not the router ID you sent. See Verify routing.

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 Any route containing a Claude family alias or Anthropic model ID. Bare firerouter needs an Anthropic or an OpenAI credential
OpenAI	Connect an OpenAI Provider Key if enabled, or send x-openai-api-key	Any route containing Astra or another OpenAI model
Amazon Bedrock	Amazon Bedrock Provider Key	A route that includes one of your mapped models. Usage bills to your AWS account.

An Anthropic or OpenAI key in a request header applies only to that request. A key connected through Provider Keys is available at the account level, so clients and gateways do not need to send it with every call.

A route containing both providers needs both credentials. You can combine an account-level key for one provider with a request header for the other.

Fireworks also accepts Anthropic credentials in x-api-key or Authorization: Bearer. One Authorization header cannot carry both the Fireworks and Anthropic keys. If it carries the Anthropic key, send the Fireworks key in X-Fireworks-Api-Key. Prefer x-anthropic-api-key for new integrations.

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

Limitations

• Accounts with data residency enabled must use a residency-compatible pinned serverless model. Other model-router requests are rejected.
• Model routers are not available through Microsoft Foundry.
• See What happens without a closed-model credential.

Errors

Response	Cause	Fix
401	Fireworks key is missing or invalid	Send a valid fw_... key with Authorization: Bearer or X-Fireworks-Api-Key
Request rejected for data residency	The requested route is not residency-compatible	Pin a residency-compatible serverless model
404 Model id not found	Unknown id, or the account cannot use this router	Check the model id and account 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.
Upstream provider authentication failure	The provider key is wrong or revoked	Check the Anthropic, OpenAI, or Amazon Bedrock key; exact status and message come from that provider

Model routers and deployment routers

A firerouter/... id is a model router. Routers load-balance traffic across your own Fireworks deployments.

See also

• FireRouter
• Provider Keys
• Routing Preferences