OpenPAI integrates Anthropic Claude over two protocols at once: OpenAI-compatible and the Claude-native /v1/messages.
Available models
| Model ID | Context | Max output | Positioning |
|---|
claude-opus-4-8 | 1M | 128K | Latest top tier — strongest at complex reasoning and long-horizon agentic coding |
claude-sonnet-4-6 | 1M | 64K | Best balance of speed and intelligence — recommended for code / reasoning / agents |
claude-haiku-4-5 | 200K | 64K | Fastest, near-frontier intelligence — first choice for everyday chat and code |
Legacy (still available)
| Model ID | Context | Notes |
|---|
claude-opus-4-7 | 1M | Previous-gen top tier |
claude-opus-4-5 | 200K | Older flagship |
claude-sonnet-4-5 | 200K | Previous-gen Sonnet |
claude-3-7-sonnet-20250219 | 200K | Interim version |
claude-3-5-sonnet-20241022 | 200K | Older, for compatibility |
Thinking
Claude can reason internally before the final answer. There are two approaches across generations:
- Extended Thinking:
claude-sonnet-4-6 and claude-haiku-4-5 set a budget_tokens thinking budget via the thinking parameter.
- Adaptive Thinking:
claude-opus-4-8 and claude-opus-4-7 are controlled by the effort parameter (low / medium / high); Opus 4.8 defaults to high and no longer uses budget_tokens.
Enable extended thinking via model ID
| Model ID | Behavior |
|---|
claude-sonnet-4-6-thinking | Sonnet 4.6, thinking enabled automatically |
claude-haiku-4-5-thinking | Haiku 4.5, thinking enabled automatically |
Enable via parameter (Claude native protocol)
# Extended thinking: Sonnet 4.6 / Haiku 4.5
curl https://openp.ai/v1/messages \
-H "x-api-key: $OPENPAI_API_KEY" \
-H "anthropic-version: 2023-06-01" \
-H "Content-Type: application/json" \
-d '{
"model": "claude-sonnet-4-6",
"max_tokens": 4096,
"thinking": { "type": "enabled", "budget_tokens": 8000 },
"messages": [{"role": "user", "content": "Prove Goldbach's conjecture"}]
}'
# Adaptive thinking: Opus 4.8 (effort defaults to high)
curl https://openp.ai/v1/messages \
-H "x-api-key: $OPENPAI_API_KEY" \
-H "anthropic-version: 2023-06-01" \
-H "Content-Type: application/json" \
-d '{
"model": "claude-opus-4-8",
"max_tokens": 4096,
"effort": "high",
"messages": [{"role": "user", "content": "Prove Goldbach's conjecture"}]
}'
Tokens produced by thinking and tokens in the final answer are billed separately (thinking_tokens vs. output_tokens), shown distinctly in the console log. Exact parameter support is subject to the console.
Examples
OpenAI-compatible protocol
from openai import OpenAI
client = OpenAI(api_key="sk-...", base_url="https://openp.ai/v1")
resp = client.chat.completions.create(
model="claude-opus-4-8",
messages=[
{"role": "system", "content": "You are a senior Go engineer."},
{"role": "user", "content": "Implement a consistent-hashing ring in Go."},
],
)
Claude native SDK
from anthropic import Anthropic
client = Anthropic(
api_key="sk-XXXXXXXXXXXXXXXX",
base_url="https://openp.ai",
)
resp = client.messages.create(
model="claude-opus-4-8",
max_tokens=2048,
system="You are a senior Go engineer.",
messages=[{"role": "user", "content": "Implement a consistent-hashing ring in Go."}],
)
print(resp.content[0].text)
tools / tool_use / tool_result tool-calling flow, fully compatible with the official Anthropic protocol.
When accessed via the OpenAI-compatible endpoint, tool calls are automatically converted to OpenAI’s tools / tool_calls structures.
See Function calling.
Vision
Supports image URL and base64 input:
{
"model": "claude-opus-4-8",
"messages": [
{
"role": "user",
"content": [
{"type": "text", "text": "What's in the image?"},
{"type": "image_url", "image_url": {"url": "https://example.com/x.png"}}
]
}
]
}
Prompt caching
Claude supports marking long context segments with cache_control to hit the prompt cache, with cache hits billed at a lower rate.
OpenPAI passes this field through verbatim — see Cache billing.
Other capabilities
Anthropic also offers Message Batches (asynchronous, ~50% off), the Files API, 1M long context, citations, and memory. Whether these are exposed through the OpenPAI gateway is subject to the console / site announcements.
API docs
