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Claude Opus 4.5 is Anthropic’s most intelligent model, combining maximum capability with practical performance across reasoning, coding, and complex problem solving.

Pricing: Input 356.25 credits / 1M tokens (≈ $1.78), Output 1787.5 credits / 1M tokens (≈ $8.94).

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README
Complete guide to using Claude Opus 4.5

Affordable Claude Opus 4.5 API – Claude API for Coding & Agents

Claude Opus 4.5 is Anthropic’s powerful model for coding, agents, and long-context reasoning. On ModelFold, you can access the Claude Opus 4.5 API with affordable pricing and free credits, making it easy to test, build, and scale real AI workflows.

Affordable Claude Opus 4.5 API – Claude API for Coding & Agents

What Is Claude Opus 4.5 API?

Introducing Claude Opus 4.5 by Anthropic

Claude Opus 4.5 API gives developers access to Anthropic’s most advanced Claude model, built for coding, reasoning, and long-running agent workflows. It is designed to handle real software tasks, from debugging and refactoring to research and computer use, and has set new benchmarks in software engineering. On ModelFold, you can use Opus 4.5 API to bring this top-tier Claude intelligence into your own products through a fast, reliable API.

Introducing Claude Opus 4.5 by Anthropic

What’s New in Claude Opus 4.5 API on ModelFold

Maximum Intelligence in Anthropic’s Claude Opus 4.5

Claude Opus 4.5 is Anthropic’s most intelligent model to date, combining stronger reasoning, deeper code understanding, and practical problem solving. Compared to Opus 4.1, it shows step-change gains across coding, analysis, and complex workflows.

Maximum Intelligence in Anthropic’s Claude Opus 4.5

Advanced Coding with Claude Opus 4.5 API

Claude Opus 4.5 delivers a major leap in real-world coding performance. It leads on SWE-bench Verified and handles multi-file changes, complex debugging, and agentic coding tasks with higher accuracy and fewer failed attempts than earlier Opus models.

Advanced Coding with Claude Opus 4.5 API

Reasoning Improvements in Opus 4.5 API

Claude Opus 4.5 reasons through ambiguity, tradeoffs, and edge cases more effectively than previous versions. With improved planning and the effort control option, it delivers more consistent logic, cleaner solutions, and fewer retries on hard engineering and research tasks.

Reasoning Improvements in Opus 4.5 API

Longer-Running Agents with Smarter Context Handling

Claude Opus 4.5 API supports longer agent workflows with better context management. On ModelFold, run extended tasks like research, refactors, and tool loops without hitting a wall. Claude Opus 4.5 API summarization keeps progress consistent.

Longer-Running Agents with Smarter Context Handling

Everyday Tasks with Claude Opus 4.5

Claude Opus 4.5 is meaningfully better at everyday work like spreadsheets, slides, and deep research. It can analyze data, generate presentations, and run long research workflows with higher accuracy and smoother context handling than earlier Opus models.

Everyday Tasks with Claude Opus 4.5

How to Use Claude Opus 4.5 API on ModelFold

  1. 1

    Step 1: Get Your Claude Opus 4.5 API Key

    Sign up or log in to ModelFold, then generate your Claude Opus 4.5 API key from the dashboard. This key gives you access to Anthropic’s Claude Opus API and allows your app to authenticate every Opus 4.5 API request.

  2. 2

    Step 2: Send Requests to Claude Opus 4.5 API

    Use the Claude Opus 4.5 API endpoint on ModelFold to send prompts, code, or tasks. You can call the Opus 4.5 API for Claude Opus 4.5 coding, data analysis, or agent workflows using standard HTTP requests.

  3. ✓

    Step 3: Receive and Use Claude Opus 4.5 Responses

    ModelFold returns structured Claude API responses that include generated text, code, or tool outputs. You can take results from Claude Opus 4.5 API and plug them directly into your product, automation, or developer workflow.

Claude Opus 4.5 vs Claude Sonnet 4.5 vs Claude Haiku 4.5

Claude 4.5 models are designed for different levels of speed, cost, and intelligence. This table shows how Haiku 4.5, Sonnet 4.5, and Claude Opus 4.5 compare.

FeatureClaude Sonnet 4.5Claude Haiku 4.5Claude Opus 4.5
DescriptionSmart Claude model built for complex agents and coding tasksFastest Claude model with near-frontier intelligencePremium Claude model combining maximum intelligence with practical performance
Best forSaaS apps, coding, agent workflowsChatbots, automation, simple tasksClaude Opus 4.5 coding, deep reasoning, advanced agents
Agentic abilityStrongBasicBest-in-class
Long-running tasksMediumShortLong, multi-step
Context handlingAdvancedStandardAdvanced with reasoning memory
Response speedFastFastestModerate
Output qualityVery goodGoodHighest

Claude Opus 4.5 vs Gemini 3 Pro

Claude Opus 4.5 and Gemini 3 Pro are both available on ModelFold, giving you access to two of the most advanced AI models through one platform. The comparison below shows how they differ in coding, reasoning, and multimodal capabilities, so you can choose the best option for your workflow.

FeatureClaude Opus 4.5Gemini 3 Pro
Core focusFrontier coding, deep reasoning, and long-running agent workflowsMultimodal intelligence, research, and general-purpose AI
Coding & logicBest-in-class for Claude Opus 4.5 coding, refactoring, and complex system debuggingStrong, but more optimized for concise and practical code
Long context handlingExcellent at large documents, deep analysis, and multi-step reasoningGood, but less focused on long-horizon agent tasks
Agent workflowsDesigned for complex agents, planning, and tool-driven orchestrationBetter suited for broad assistant and research workflows
Multimodal abilityText-first, optimized for logic and codeBest for video, image, and UI understanding
Output styleDetailed, insightful, and preciseConcise, efficient, and fast
Ecosystem integrationStrong for developer tools and AI agentsDeep integration with Google Search and Google tools
Best use casesAdvanced software engineering, reasoning, and Claude Opus 4.5 API agentsMultimodal research, UI ideas, and large-scale general AI use

Claude Opus 4.5 vs GPT-5.2 Codex

Claude Opus 4.5 and GPT-5.2 Codex are two of the strongest coding models available today. Both score around 80% on SWE-bench Verified, which means they can fix real GitHub issues in large codebases. The key difference is how they approach coding, reasoning, and production workflows.

FeatureClaude Opus 4.5GPT-5.2 Codex
Overall coding performanceLeads SWE-bench Verified with 80.9%, strong on real-world repositoriesVery close at 80.0%, state-of-the-art on SWE-bench Pro
Code qualityClean, well-structured, and defensive, designed for long-term maintainabilityConcise and fast, but more likely to cause integration or version issues
Long-context workExcellent for large codebases, refactors, and multi-file changesVery strong, but less focused on long-running agent workflows
Agent workflowsBuilt for agentic coding, planning, and tool-driven orchestrationStrong for fast single-agent coding and rapid iteration
Terminal and DevOpsMuch stronger command-line and multi-step workflow handlingGood, but less consistent with complex terminal tasks
Mathematical reasoningVery strong, but not top in pure math benchmarksBest-in-class for math, algorithms, and formal reasoning
Output styleMore detailed and explanatory, better for reviews and refactoringShorter and more direct, better for quick coding
Best use casesArchitecture, refactoring, large systems, Claude Opus 4.5 coding, and production agentsAlgorithms, fast prototyping, cost-sensitive or math-heavy coding

Why Choose Claude Opus 4.5 API on ModelFold

Claude Opus 4.5 Free Credits to Test Before You Pay

ModelFold gives you free credits to try Claude Opus 4.5 free before committing. You can test Claude Opus 4.5 API on real coding, reasoning, and agent tasks to see how it fits your workflow, without risk or upfront cost.

Affordable Claude Opus 4.5 API Pricing for Real Workloads

Claude Opus 4.5 API pricing on ModelFold is built to be affordable and flexible, from first tests to large-scale production. You can start small, scale up as your usage grows, and keep predictable costs while using Opus-level Claude API performance for real workloads.

Access Claude API and Other Top LLM APIs

ModelFold gives you more than Claude Opus 4.5 API. You can also use Gemini 3 Pro, GPT-5.2, and other top models through one platform. This lets you combine Claude Opus API with other best LLM APIs to build faster, smarter, and more flexible AI products.

Frequently Asked Questions

What is Claude Opus 4.5 API?⌄

Claude Opus 4.5 API is Anthropic’s advanced Claude API for coding, reasoning, and long-running agents. It gives developers access to Opus-level intelligence for complex software and automation tasks.

How do I get a Claude Opus 4.5 API key?⌄

You can get a Claude Opus 4.5 API key by creating an account on ModelFold and generating one from the dashboard. Once created, you can use that key to call the Claude Opus API in your application.

Is Claude Opus 4.5 API good for coding?⌄

Yes. Claude Opus 4.5 coding is designed for real-world software work, including debugging, refactoring, and multi-file changes.

How does Claude Opus 4.5 differ from Sonnet 4.5 and Haiku 4.5?⌄

Claude Opus API provides the highest level of reasoning and coding performance. Sonnet and Haiku are faster and cheaper, but Opus 4.5 API is built for complex logic, deep analysis, and advanced agent workflows.

How does Claude Opus 4.5 compare to Gemini 3 Pro?⌄

Claude Opus 4.5 is stronger for deep coding, reasoning, and long-running agents, while Gemini 3 Pro is better for multimodal tasks like images, video, and UI-focused workflows.

How does Claude Opus 4.5 compare to GPT-5.2 Codex?⌄

Claude Opus 4.5 focuses on clean architecture, long-context understanding, and agentic coding, while GPT-5.2 Codex is faster and strong at algorithms and math-heavy tasks.

How to access Claude 4 Opus for free?⌄

ModelFold offers free credits so you can try Claude Opus 4.5 free before committing to a paid plan and test it on your own prompts and projects.

Rate card
Input356.25 credits 1M tokens≈ $1.78
Output1787.5 credits 1M tokens≈ $8.94

Billed per token: input and output are priced separately, and thinking tokens count as output. The Playground charges exactly the same way.

Read API docs →
Quick start
curl https://ai.modelfold.online/v1/chat/completions \
  -H "Authorization: Bearer $MODELFOLD_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"claude-opus-4-5","messages":[{"role":"user","content":"Hello"}]}'