Claude Opus 4.5
Claude Opus 4.5 is Anthropic's flagship, leading on real-world software engineering and long-horizon agentic coding and deep research. Access it through Velokey's unified endpoint with below-list pricing.
Use cases
Complex coding & code migration · Financial modeling & spreadsheet automation
Input
Text
Output
Text
Billing
Per token
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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
| Spec | Price | Official | Savings |
|---|---|---|---|
| Input/1M tokens | 4 Credits≈$4 | 5 Credits | -20% |
| Output/1M tokens | 20 Credits≈$20 | 25 Credits | -20% |
| Cache Read/1M tokens | 0.4 Credits≈$0.4 | 0.5 Credits | -20% |
| Cache Write/1M tokens | 5 Credits≈$5 | 6.25 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.
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Affordable Claude Opus 4.5 API
Access Anthropic's Opus 4.5 on Velokey — SOTA software engineering, an adjustable effort parameter, subagent coordination, and the strongest alignment, with a unified endpoint and below-list pricing for production apps.
Meet Claude Opus 4.5 and its API access
Claude Opus 4.5 is Anthropic's flagship model released on November 24, 2025, reaching state-of-the-art on real-world software engineering (SWE-bench Verified) and excelling at multilingual coding, long-horizon agent tasks, and autonomous planning. It offers a 200K-token context window, introduces an adjustable effort parameter, and finishes the same work with fewer output tokens — while being Anthropic's most robustly aligned, prompt-injection-resistant model at release. Velokey provides an affordable, easy-to-integrate Claude Opus 4.5 API: a unified chat endpoint, a clear request flow, and below-list pricing for production systems, agent pipelines, and automation tools.
SOTA coding & code migration
Reaches state-of-the-art on real-world software engineering and excels across most major languages — fit for complex code migration, large-codebase refactoring, and debugging, including long autonomous engineering runs.
View Documentation →
Adjustable effort parameter
Tune reasoning depth with the effort parameter to balance capability, speed, and cost. At a medium setting it finishes the same work with markedly fewer output tokens, keeping costs predictable.
View Documentation →
Long-horizon agents & subagent coordination
Excels at multi-step autonomous workflows and long-context tasks, coordinating subagent teams effectively — stable on long-running agent systems and autonomous planning.
View Documentation →
Strongest alignment & prompt-injection resistance
Anthropic's most robustly aligned model at release, with clear improvements in prompt-injection robustness over peers — better suited to user-facing production systems.
View Documentation →
How to deploy the Claude Opus 4.5 API on Velokey
Get started with just a few steps.
Sign up and get an API Key
Sign in to the Velokey console to generate an API Key that authenticates every request sent to Claude Opus 4.5.
Configure request parameters
Set model to claude-opus-4-5, submit messages, and use the effort parameter to tune reasoning depth per task, balancing capability, speed, and cost.
Integrate and start calling
Send requests to Velokey's unified /v1/chat/completions endpoint to power assistants, agents, and automation, with usage managed in one console.
Real-world use cases for Claude Opus 4.5
From engineering to enterprise knowledge work, covering many high-autonomy scenarios.
Complex coding & code migration
State-of-the-art on real engineering — fit for migration, refactoring, and debugging across large codebases and long autonomous runs.
Long-horizon agents & subagents
Excels at multi-step autonomous workflows, coordinating subagent teams effectively — fit for long-running agent systems.
Deep research & analysis
Strong at long-context research, cross-source synthesis, and deep analysis — fit for research and decision support.
Financial modeling & spreadsheet automation
Fit for spreadsheet, slide, and financial-modeling work that needs high reliability across multi-step enterprise processes.
Alignment-sensitive production systems
With stronger alignment and prompt-injection resistance, fit for user-facing, safety-sensitive production systems.
Long-document analysis
A 200K-token context fits retrieval, synthesis, and analysis across long contracts, reports, and material.
Why choose Velokey for Claude Opus 4.5
Discount on list price
Call Claude Opus 4.5 at a lower price on Velokey — pay-as-you-go with no forced subscription, reducing upfront cost.
Unified API interface
One API Key accesses Claude Opus 4.5 and other models — no juggling multiple accounts and keys, simplifying integration.
Complete docs and migration guidance
Endpoint references, parameter details, and migration examples help you quickly adopt the effort parameter and more.
Stable and highly available
Automatic failover and stable fallback routes maintain availability when the primary route is down, keeping production reliable.
API Reference
Complete API call examples and parameter descriptions
Endpoint
https://api.velokey.ai/v1/messagesAuthentication
Bearer YOUR_API_KEYRequest 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-4-5-20251101",
"messages": [{"role": "user", "content": "Hello!"}],
"temperature": 0.7
}'Response Example
{
"id": "req_abc123",
"model": "claude-opus-4-5-20251101",
"created": 1234567890,
"data": { ... }
}Claude Opus 4.5 API FAQ
What stands out about Claude Opus 4.5?
It reaches state-of-the-art on real-world software engineering, excels at multilingual coding, long-horizon agent tasks, and autonomous planning, and introduces an adjustable effort parameter with higher token efficiency — while being Anthropic's most robustly aligned model at release.
How does the effort parameter work?
The effort parameter tunes the model's reasoning depth: lower settings suit cost- or latency-sensitive tasks, higher settings suit complex problems. It lets you balance capability, speed, and cost, finishing the same work with fewer output tokens.
How large is the context window?
Claude Opus 4.5 offers a 200K-token context window, fit for long documents, long conversations, and long-context agent tasks.
What is it best for?
Complex coding and code migration, deep research and analysis, financial modeling and spreadsheet automation, long-running autonomous tasks, and multi-step enterprise workflows.
How is it billed on Velokey?
Official pricing is $5 input / $25 output per million tokens. This page's pricing area shows the current Velokey price, billed by input and output tokens with a discount on list price.
Start building with Claude Opus 4.5 today
Use one API key to access low-cost, stable AI models through Velokey.