Base URL:

https://api.tryarcflow.com

User authentication:

Authorization: Bearer sk-...

Public endpoints such as /v1/models and /v1/ping do not require a bearer according to the OpenAPI schema.

Runtime

Method	Path	Description
`GET`	`/v1/ping`	API ping.
`GET`	`/v1/models`	List the model catalog.
`GET`	`/v1/models/{model}`	Retrieve one model metadata.

OpenAI-compatible

Method	Path	Description
`POST`	`/v1/responses`	Create a Responses API response, with SSE when `stream=true`.
`GET`	`/v1/responses/{response_id}`	Retrieve a response.
`POST`	`/v1/chat/completions`	Forward Chat Completions to the configured upstream.
`POST`	`/v1/conversations`	Create a conversation container.
`GET`	`/v1/conversations/{conversation_id}`	Retrieve a conversation.
`POST`	`/v1/conversations/{conversation_id}`	Update a conversation.
`DELETE`	`/v1/conversations/{conversation_id}`	Delete a conversation.

Responses example

curl https://api.tryarcflow.com/v1/responses \
  -H "Authorization: Bearer $ARCFLOW_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-5.4",
    "input": "Write a one sentence release note."
  }'

The minimal body requires model. input can contain text, messages, images, files, or tool results depending on the Responses format you use.

Claude-compatible

Method	Path	Description
`POST`	`/v1/messages`	Create a Claude message through Anthropic Messages.
`POST`	`/v1/messages/count_tokens`	Count Claude tokens.

Messages example

curl https://api.tryarcflow.com/v1/messages \
  -H "Authorization: Bearer $ARCFLOW_API_KEY" \
  -H "Content-Type: application/json" \
  -H "anthropic-version: 2023-06-01" \
  -d '{
    "model": "claude-sonnet-4-6",
    "max_tokens": 128,
    "messages": [{ "role": "user", "content": "Reply with ok" }]
  }'

Files

Method	Path	Description
`POST`	`/v1/files`	Upload multipart form data.
`PUT`	`/v1/files/{path}`	Upload by streaming the request body.

Usage

Method	Path	Description
`GET`	`/v1/usage`	Budget for the authenticated API key.

Common errors

Status	Meaning
`400`	Invalid body or unavailable model.
`401`	Missing or invalid key.
`402`	API key budget exhausted.
`502`	Upstream failure.
`503`	Provider, repository, or capacity unavailable.

API Reference