How do I use Claude Opus 4.5 through YepAPI?

Sign up for a free API key, then send requests to the /v1/ai/chat endpoint.

AnthropicText Generation/v1/ai/chat

Claude Opus 4.5

Access Claude Opus 4.5 through one API key. OpenAI-compatible, pay per token.

Anthropic's Claude 4.5 flagship for complex software engineering, agentic workflows and long-horizon computer use, with a 200K token context window and 64K output tokens.

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2,400+

Developers

1.2M+

API calls served

100+

Endpoints

$0.01

Per call

Yep, that's it.

Try it live

Send a message and see Claude Opus 4.5 respond in real time.

POST/v1/ai/chatanthropic/claude-opus-4.5

Message *

Max Tokens

Maximum tokens in the response.

Stream

Real-time tokens

Hit "Send Request" to see the response

Context Window

200K tokens

Max Output

64K tokens

Input Price

$7.38 / 1M tokens

Output Price

$36.92 / 1M tokens

Strengths

✓

Claude 4.5 flagship

The top of the Claude 4.5 line, built for demanding software engineering and agentic work.

✓

Long-horizon computer use

Strong at multi-step tasks that operate tools and interfaces over many turns.

✓

200K context, 64K output

Handles up to 200,000 input tokens and returns up to 64,000 output tokens per call.

✓

Tools, vision and structured output

Function calling, image and file input, and JSON schema outputs.

Quick start

Copy this snippet and start making calls with Claude Opus 4.5.

const res = await fetch('https://api.yepapi.com/v1/ai/chat', {
  method: 'POST',
  headers: {
    'x-api-key': 'YOUR_API_KEY',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    "model": "anthropic/claude-opus-4.5",
    "messages": [
      {
        "role": "user",
        "content": "Explain API gateways in 2 sentences."
      }
    ],
    "maxTokens": 256
  }),
});
const { data } = await res.json();
console.log(data.message.content);

Why use Claude Opus 4.5 through YepAPI?

✓One API key for all models — no separate accounts

✓OpenAI SDK compatible — just change the base URL

✓No monthly minimums — pay per token

✓Switch models with one line of code

✓Full provider passthrough — citations, search results, and all extras included

✓Streaming and non-streaming support on every model

✓Works with Cursor, Claude, LangChain, and any LLM tool

✓Unified billing across all providers

Claude Opus 4.5 API — pricing, context window & access

Claude Opus 4.5 is Anthropic's frontier reasoning model of the Claude 4.5 generation, optimised for complex software engineering, agentic workflows and long-horizon computer use, with strong multimodal capabilities. It pairs a 200,000-token context window with up to 64,000 output tokens per response, at $7.38 per 1M input and $36.92 per 1M output tokens through YepAPI.

Through YepAPI you call Claude Opus 4.5 on an OpenAI-compatible endpoint with a single key — the same key that reaches the rest of the Claude line, GPT-6, Gemini and the SEO, SERP and scraping APIs.

What is Claude Opus 4.5?

Claude Opus 4.5 is Anthropic's frontier reasoning model of the Claude 4.5 generation, optimised for complex software engineering, agentic workflows and long-horizon computer use, with strong multimodal capabilities. It remains a solid choice for teams with prompts tuned against it; new work should start on Claude Opus 5.5, which is stronger and cheaper.

Build with Claude Opus 4.5 via YepAPI

YepAPI serves Claude Opus 4.5 on the OpenAI-compatible /v1/ai/chat endpoint. Point your base URL at YepAPI, add your key, and set the model string to claude-opus-4.5 (or the full anthropic/claude-opus-4.5). Switching to a newer Claude, or to any other model on the platform, is a one-string change per request.

Claude Opus 4.5 API pricing — $7.38 / 1M input, $36.92 / 1M output

Claude Opus 4.5 costs $7.38 per 1M input tokens and $36.92 per 1M output tokens through YepAPI, pay per token with no minimums. Failed calls are never charged, and every request is itemised in your dashboard API Logs.

Try Claude Opus 4.5 free

Every new YepAPI account includes $5 in free credit with no card required. Create an account, copy your key, and call claude-opus-4.5 right away.

Start generating in 30 seconds

$5 free credit on signup. No credit card required. Pay per call.

Get API Key

What developers say

“Switched from SerpAPI and cut our SERP costs by 80%. Same data quality, way simpler billing.”
Marcus T.
SEO Platform Founder

“One API key for AI models, SERP data, and web scraping. Saved us from managing 4 separate providers.”
Priya S.
Full-Stack Developer

“The $5 free credit let us prototype our entire rank tracking feature before committing. No other API does that.”
Jake R.
Indie Hacker

Frequently asked questions

Anthropic's Claude 4.5 flagship for complex software engineering, agentic workflows and long-horizon computer use, with a 200K token context window and 64K output tokens.

Input tokens cost $7.38 per 1M tokens and output tokens cost $36.92 per 1M tokens through YepAPI. No monthly minimums — you only pay for what you use.

Claude Opus 4.5 supports a 200K token context window with up to 64K output tokens per request.