runapi-ai Claude on RunAPI
Use Anthropic Messages at https://runapi.ai with POST /v1/messages as the primary protocol.
Primary protocol recipe
Authenticate
Set ANTHROPIC_API_KEY to a RunAPI API key and ANTHROPIC_BASE_URL to
https://runapi.ai. The SDK sends x-api-key; Bearer authentication is also accepted.
Send request
import anthropic
client = anthropic.Anthropic(api_key="YOUR_RUNAPI_TOKEN", base_url="https://runapi.ai")
message = client.messages.create(
model="claude-sonnet-5",
max_tokens=1024,
messages=[{"role": "user", "content": "Explain this decision."}],
)
print(message.content[0].text)
print(message.usage)
max_tokens is required. For long output, use client.messages.stream(...)
and consume stream.text_stream through the terminal event. Add image blocks,
function tools, reasoning controls, or token counting only when the current
RunAPI contract verifies them for the selected exact model.
Verify result
Require final text, stop_reason, and authoritative usage. A stream is
complete only after terminal Usage and message_stop. Token counting estimates
input only; actual response Usage remains authoritative.
Stop boundaries
Correct a rejected shape once using the structured error. Retry transport once only before any response or Usage and when replay is safe. Record a terminal error and stop without changing model or protocol.
Compatibility protocols
Load compatibility protocols only when an existing client requires OpenAI Chat/Responses or Gemini contents.
Supported models
| Model ID | Use when |
|---|---|
claude-fable-5-1 |
— |
claude-fable-5 |
Flagship state-of-the-art coding, reasoning, and vision |
claude-sonnet-5 |
Near-Opus coding at Sonnet cost |
claude-opus-5 |
Latest Opus frontier reasoning |
claude-opus-4-8 |
Strongest general model |
claude-opus-4-7 |
Previous Opus generation |
claude-opus-4-6 |
High-end reasoning |
claude-sonnet-4-6 |
Balanced reasoning and speed |
claude-opus-4-5-20251101 |
Dated Opus 4.5 snapshot |
claude-sonnet-4-5-20250929 |
Dated Sonnet 4.5 snapshot |
claude-haiku-4-5-20251001 |
Fastest lightweight snapshot |
claude-opus-4-1-20250805 |
Dated Opus 4.1 snapshot |