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Claude Opus 4.8

AnthropicChatin 4 · out 20 Credits / 1M tokens≈$4 / $20Available
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Claude Opus 4.8 is Anthropic's most powerful Opus model to date, built for complex reasoning and long-running, high-autonomy agentic coding. Access it through Velokey's unified endpoint with below-list pricing.

1M-token context128K-token outputAdaptive thinkingVision multimodal

Use cases

Codebase-scale migrations · Legal and financial document analysis

Input

Text, image

Output

Text

Billing

Per token

0.7
02
2048
2568192
claude-opus-4-8

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Sign up to get $0.5 in free credits — about 20 free images

Pricing details

Transparent usage-based pricing with no hidden fees.

Detailed Pricing

Usage-based pricing breakdown

SpecPriceOfficialSavings
Input/1M tokens4 Credits≈$45 Credits-20%
Output/1M tokens20 Credits≈$2025 Credits-20%
Cache Read/1M tokens0.4 Credits≈$0.40.5 Credits-20%
Cache Write/1M tokens5 Credits≈$56.25 Credits-20%

Billing Rules

  • Output price varies by model, resolution, quality, duration, or token usage.
  • Uploaded reference files may be charged separately when supported.
  • Add-on capabilities such as web search or image search may be billed per request.
  • Token-based models are billed by input and output tokens.
  • If the primary route is unavailable, Velokey may automatically switch to a stable fallback route when possible.
  • Usage is pay-as-you-go with transparent credit deduction.

* Final cost depends on the generated result.

Related models

Explore other models in the same family.

Affordable Claude Opus 4.8 API

Access Anthropic's most powerful Opus-tier model on Velokey — 1M-token context, adaptive thinking, and stable long-running agentic coding, with a unified endpoint and discount on official pricing for production-ready apps.

Meet Claude Opus 4.8 and its API integration

Claude Opus 4.8 is Anthropic's flagship Opus-tier model released in May 2026, comprehensively improving coding, agentic tasks, reasoning, and knowledge work on top of Opus 4.7 at the same price. It defaults to a 1M-token context window, 128K-token max output, and adaptive thinking — particularly fit for long-running autonomous coding, codebase-scale migrations, and complex document analysis.\n\nVelokey offers an affordable, integration-friendly Claude Opus 4.8 API: a unified chat endpoint, a clean request flow, and a discount on top of official pricing — ready to drop into production systems, agent pipelines, and automation tools.

1M-token long context

Defaults to a 1M-token context window and 128K-token output, maintaining coherence across very long codebases, documents, and conversations, with less compression and improved post-compression recovery.

View Documentation →
1M-token long context

Adaptive thinking, on-demand reasoning

The model decides on a per-turn basis whether to think: simple steps get direct responses, complex problems get reasoning-first answers. At the same effort level, reduces unnecessary thinking tokens for better cost efficiency in agent loops.

View Documentation →
Adaptive thinking, on-demand reasoning

Stronger tool triggering and honesty

Fewer missed tool calls for required tasks; the probability of letting its own code flaws go unremarked is roughly one-quarter of 4.7's; more proactive in flagging uncertainty in agentic tasks.

View Documentation →
Stronger tool triggering and honesty

Mid-conversation system injection

Supports inserting role: system messages in the messages array after user turns, updating instructions mid-stream without restating the full system prompt, preserving prompt cache hits from earlier turns for lower input costs in long flows.

View Documentation →
Mid-conversation system injection

How to deploy the Claude Opus 4.8 API on Velokey

Just a few steps to start calling.

1

Sign up and get an API Key

Sign in to the Velokey dashboard to generate an API Key that authenticates every request sent to Claude Opus 4.8.

2

Migrate your request

Set model to claude-opus-4-8. If migrating from an older version, remove manual thinking budgets, switch to thinking: adaptive, and set output_config.effort to high or another level; also remove unsupported sampling parameters like temperature.

3

Integrate and start calling

Send requests to Velokey's unified /v1/chat/completions endpoint to power assistants, agents, and automation, and manage usage from one dashboard.

Claude Opus 4.8 real-world use cases

From engineering to knowledge work, across many high-autonomy scenarios.

Long-running agentic coding

Fit for long-running autonomous engineering tasks with less long-context dropout and more stable compression recovery, consistently advancing multi-step coding workflows.

Codebase-scale migrations

With 1M-token context, handles large-scale refactoring, framework upgrades, and migrations across hundreds of thousands of lines of code.

Legal document analysis

Maintains context coherence across lengthy contracts and legal documents — fit for contract review and other high-reliability knowledge work.

Financial analysis

Maintains context across lengthy financial reports and complex financial models — fit for analysis that spans large amounts of data.

Deep research

Organizes lengthy academic materials, breaks down complex problems, and generates structured conclusions while maintaining cross-document context coherence.

Multimodal reasoning

Supports vision input for multimodal reasoning on PDFs, charts, and screenshots — fit for document analysis requiring visual understanding.

Why choose Velokey for Claude Opus 4.8

A discount on official pricing

Call Claude Opus 4.8 at a lower price on Velokey — pay-as-you-go with no mandatory subscription, reducing upfront cost.

Unified API interface

One API Key accesses Claude Opus 4.8 and other models — no juggling multiple accounts and keys, simplifying integration.

Thorough docs and migration guidance

Endpoint references, parameter details, and migration examples help you smoothly upgrade from 4.7 to 4.8 and make the most of new capabilities.

Stable and highly available

Automatic failover and stable backup routing maintain availability when a primary route is down, keeping production steady.

API Reference

Complete API call examples and parameter descriptions

Endpoint

https://api.velokey.ai/v1/messages

Authentication

Bearer YOUR_API_KEY

Request Example

curl https://api.velokey.ai/v1/messages \
  -X POST \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-opus-4-8",
    "messages": [{"role": "user", "content": "Hello!"}],
    "temperature": 0.7
  }'

Response Example

{
  "id": "req_abc123",
  "model": "claude-opus-4-8",
  "created": 1234567890,
  "data": { ... }
}

Claude Opus 4.8 API FAQ

What's improved in Claude Opus 4.8?

Compared to Opus 4.7, it improves long-running agentic coding, reasoning effort calibration, and tool triggering: better long-context handling, less compression, fewer missed tool calls, at the same price.

What are the context window and max output?

On Claude API, Amazon Bedrock, and Google Cloud, it defaults to a 1M-token context window (200K on Microsoft Foundry) with 128K-token max output.

Why does setting temperature return an error?

Like 4.7, Opus 4.8 does not support temperature, top_p, or top_k sampling parameters; setting non-default values returns 400. Guide model behavior via prompts instead.

How do I control its thinking depth?

Opus 4.8 only supports adaptive thinking (adaptive thinking), not manual thinking budgets. Set thinking to adaptive and use the effort parameter (default high; also extra/xhigh and max) to control thinking and output depth.

How is it billed on Velokey?

The pricing section on this page shows the current Velokey price for Claude Opus 4.8, billed by input and output tokens with a discount on top of official pricing. Credits are managed centrally in your Velokey account.

Start building with Claude Opus 4.8 today

Use one API key to access low-cost, stable AI models through Velokey.

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