AnthropicText Generation/v1/ai/chatReasoning

Claude Opus 5 API

Access Claude Opus 5 through one API key. Anthropic Opus 5 Flagship.

Claude Opus 5 is Anthropic's flagship model for demanding reasoning, coding and long-horizon agentic work, the first of the Claude 5 generation. Opus 5 remains useful for teams that have validated prompts against it and want a stable target; new projects should start with Opus 5.5.

Full Docs Get API Key

Takes 30 seconds.

Claude Opus 5 API pricing

Pay per request from your YepAPI balance — no subscription, no monthly minimum. Prices updated September 27, 2026.

Token type	Price
Input	$7.38 / 1M tokens
Output (incl. reasoning)	$36.92 / 1M tokens
Context window	1M tokens

What it costs	Per job	Per 1,000
Chat reply1K input + 500 output tokens	$0.026	$25.84
RAG answer8K input + 800 output tokens	$0.089	$88.58
Agent step with tools30K input + 2K output tokens	$0.295	$295.24
Long document summary100K input + 2K output tokens	$0.812	$811.84

4,900+

Developers

2.3M+

API calls served

184

Endpoints

$0.01

Per call

Yep, that's it.

Try it live

Send a message and see Claude Opus 5 respond in real time.

POST/v1/ai/chatanthropic/claude-opus-5

Message *

Max Tokens

Maximum tokens in the response.

Stream

Real-time tokens

Hit "Send Request" to see the response

Claude Opus 5 specs

Provider	Anthropic
Model ID	anthropic/claude-opus-5
Endpoint	/v1/ai/chat
Type	Text Generation
Context window	1M tokens
Max output	128K tokens
Reasoning	Yes
OpenAI-compatible	Yes — /v1/ai/chat/completions

How to get a Claude Opus 5 API key

1
Create an account
Sign up at yepapi.com with Google or email. It takes about 30 seconds.
2
Create an API key
Open the dashboard, go to API Keys and create a key. Copy it — it starts with yep_sk_.
3
Call Claude Opus 5
Send a request to /v1/ai/chat with the x-api-key header and model "anthropic/claude-opus-5".
4
Pay as you go
Usage is billed per request from your balance. Top up any amount; there is no subscription.

Strengths

✓

First Claude 5 flagship

Introduced the Claude 5 generation's 1M context and 128K output for Opus-class reasoning.

✓

End-to-end software tasks

Strong at implementing, reviewing and debugging across a codebase in one run.

✓

1M token context, 128K output

Handles up to 1,000,000 input tokens and returns up to 128,000 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 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-5",
    "messages": [
      {
        "role": "user",
        "content": "Explain API gateways in 2 sentences."
      }
    ],
    "maxTokens": 256
  }),
});
const { data } = await res.json();
console.log(data.message.content);

Claude Opus 5 vs similar models

Every model below runs on the same API key — switch by changing the model ID.

Model	Provider	Price	Context
Claude Opus 5	Anthropic	$7.38 in / $36.92 out per 1M	1M
Claude Haiku 5.5	Anthropic	$0.15 in / $0.74 out per 1M	1M
Claude Haiku 4.5	Anthropic	$1.48 in / $7.38 out per 1M	200K
Claude Sonnet 5	Anthropic	$2.95 in / $14.77 out per 1M	1M
Claude Sonnet 5.5	Anthropic	$2.95 in / $14.77 out per 1M	1M
Claude Sonnet 4.6	Anthropic	$4.43 in / $22.15 out per 1M	1M
Nemotron 3 Super	NVIDIA	$0 in / $0 out per 1M	262K
Qwen3.7 Flash	Qwen	$0.04 in / $0.19 out per 1M	1M

Why use Claude Opus 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 5 API — pricing, context window & access

Claude Opus 5 is Anthropic's flagship model for demanding reasoning, coding and long-horizon agentic work, the first of the Claude 5 generation. It pairs a 1,000,000-token context window with up to 128,000 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 5 on an OpenAI-compatible endpoint with a single key — the same key that reaches GPT-6, Claude, Gemini, Grok and the SEO, SERP and scraping APIs. Input: text, images, files.

What is Claude Opus 5?

Claude Opus 5 is Anthropic's flagship model for demanding reasoning, coding and long-horizon agentic work, the first of the Claude 5 generation. It is particularly strong at end-to-end software tasks, code review and bug finding, and visual analysis, with a 1,000,000-token context window and up to 128,000 output tokens. It is succeeded by Claude Opus 5.5, which is both stronger and cheaper. It accepts text, images, files as input, handles up to 1,000,000 tokens of context and returns up to 128,000 output tokens per call.

Build with Claude Opus 5 via YepAPI

YepAPI serves Claude Opus 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-5 (or the full anthropic/claude-opus-5). Function calling, structured outputs and reasoning settings pass straight through, and switching to any other model on the platform is a one-string change per request.

Claude Opus 5 API pricing — $7.38 / 1M input, $36.92 / 1M output

Claude Opus 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 so you can see exactly what a 128,000-token response cost.

Claude Opus 5 use cases

Opus 5 remains useful for teams that have validated prompts against it and want a stable target; new projects should start with Opus 5.5.

Start generating in 30 seconds

Pay per call, no subscriptions.

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

Claude Opus 5 costs $7.38 per 1M input tokens and $36.92 per 1M output tokens through YepAPI, billed per request with no monthly fee. For example, a chat reply (1K input + 500 output tokens) costs about $0.026.

Sign up at yepapi.com (Google or email, about 30 seconds), open the dashboard and create an API key. The same key works for Claude Opus 5 and every other model — no separate Anthropic account or waitlist.

Use "anthropic/claude-opus-5" as the model on /v1/ai/chat. The short alias "claude-opus-5" also works.

Yes. Point the OpenAI SDK at https://api.yepapi.com/v1/ai with your YepAPI key and set model to "anthropic/claude-opus-5". Streaming works the same way, so existing OpenAI code only needs the base URL and key changed.

Claude Opus 5 supports a 1M token context window with up to 128K output tokens per request.