Claude Opus 5 API — Access via an AI API Gateway
Call Anthropic’s Claude Opus 5 through byesu — an AI API gateway with pay-as-you-go billing and no subscription. It supports both the Anthropic-native and the OpenAI-compatible API, and plugs into Claude Code with environment variables.
Model specs below are quoted from Anthropic’s official documentation, checked on 2026-10-22.
What It Is
Claude Opus 5 was released on July 24, 2026. Anthropic now lists it as a legacy model: it is still available, but Anthropic recommends migrating new work to the current Opus model, Claude Opus 5.5. If your prompts, evals or workflows are already tuned for Opus 5 and you want consistent behavior, you can keep using claude-opus-5.
| Item | Value |
|---|---|
| Model ID on byesu | claude-opus-5 |
| Context window | 1M tokens |
| Max output | 128K tokens |
| Input → output | Text and images → text |
| Thinking | Adaptive thinking, default effort high |
| Knowledge cutoff | May 2026 |
| Status | Legacy; retirement not sooner than July 24, 2027 |
How Pricing Works
byesu bills per token with no monthly fee. The actual price of every model is shown live in the model list after you sign in, and the console records the charge for each request.
For reference, Anthropic’s official list price is $5 / $25 per million input / output tokens; cache reads are $0.50 (10% of the input price), 5-minute cache writes $6.25 and 1-hour cache writes $10. Claude Opus 5.5 has a lower list price ($4 / $20).
TIP
claude-opus-5 is served by the Claude groups in the console. The Claude group is in the default auto-group list, so a token in the default auto group can call it — no need to pick a group. You can also create a token in a Claude group to pin the route. A wrong group returns “no available channel”; see Choosing a Group.
How to Call It
The base URL depends on the API format:
- Anthropic native (
/v1/messages) →https://byesu.com - OpenAI-compatible (
/v1/chat/completions) →https://byesu.com/v1
Authenticate with Authorization: Bearer sk-YOUR_TOKEN.
Option 1: Anthropic native /v1/messages
curl https://byesu.com/v1/messages \
-H "Authorization: Bearer sk-YOUR_TOKEN" \
-H "anthropic-version: 2023-06-01" \
-H "Content-Type: application/json" \
-d '{
"model": "claude-opus-5",
"max_tokens": 1024,
"messages": [
{
"role": "user",
"content": "Explain what an API gateway is in one sentence"
}
]
}'Option 2: OpenAI-compatible /v1/chat/completions
from openai import OpenAI
client = OpenAI(api_key="sk-YOUR_TOKEN", base_url="https://byesu.com/v1")
resp = client.chat.completions.create(
model="claude-opus-5",
messages=[{"role": "user", "content": "Explain what an API gateway is in one sentence"}],
)
print(resp.choices[0].message.content)Use It in Claude Code
Point Claude Code at byesu with environment variables (the base URL has no /v1):
export ANTHROPIC_BASE_URL="https://byesu.com"
export ANTHROPIC_API_KEY="sk-YOUR_TOKEN"
export ANTHROPIC_MODEL="claude-opus-5"Full steps and a one-line setup script: Claude Code CLI.
FAQ
Should I use Claude Opus 5 or Claude Opus 5.5?
Anthropic lists Opus 5 as a legacy model and recommends Opus 5.5 for new work; Opus 5.5 also has a lower list price ($4 / $20 vs $5 / $25). If your prompts and evals are tuned for Opus 5 and you need consistent output, keep using claude-opus-5. On byesu both work with the same token — just change the model name.
How much does the Claude Opus 5 API cost on byesu?
byesu bills per token with no subscription; the live price is shown in the model list after you sign in. For reference, Anthropic’s official list price is $5 / $25 per million input / output tokens.
How long is the Claude Opus 5 context window?
According to Anthropic’s documentation, the context window is 1M tokens with up to 128K output tokens per request.
Can I call Claude Opus 5 with the OpenAI SDK?
Yes. Set the SDK base_url to https://byesu.com/v1, use your byesu token as the api_key, and set model to claude-opus-5.
What does “no available channel” mean when calling claude-opus-5?
Check that the token uses the default auto group or a Claude group, and that the model ID is exactly claude-opus-5, as shown in the console.