claude-opus-4-1
Claude Opus 4.1 is an updated version of Anthropic’s flagship Opus model, with improved performance in coding, reasoning and agentic tasks.
Pricing: Input 3600 credits / 1M tokens (≈ $18.00), Output 18000 credits / 1M tokens (≈ $90.00).
Prices updated
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Claude Opus 4.1 API on ModelFold
Claude Opus 4.1 is an updated version of Anthropic’s flagship Opus model, with improved performance in coding, reasoning and agentic tasks. Try Claude Opus 4.1 in the ModelFold Playground, then call it from your own code through an OpenAI-compatible chat completions API.
What Is the Claude Opus 4.1 API
Claude Opus 4.1 at a glance
Claude Opus 4.1 is a chat model from Anthropic. It accepts text, images and files (such as PDF) as input and returns text, with a context window of up to 200K tokens.
Use it without hosting anything
On ModelFold you call Claude Opus 4.1 with a single API key — no model weights to download and no inference servers to run. The same key also works for the other chat, image, video and audio models on ModelFold.
Core Capabilities of Claude Opus 4.1
Up to 200K tokens of context
Keep long conversations, large documents and sizeable code in a single request, so the model can reason over the full material instead of fragments.
Understands images and files (such as PDF)
Besides text, Claude Opus 4.1 accepts images and files (such as PDF) as input, so a single request can combine instructions with visual or other media.
Function calling
Claude Opus 4.1 supports tool (function) calling: describe your functions in the request and the model returns structured calls your code can run — the basis for agents and integrations.
Reasoning mode
Claude Opus 4.1 can produce reasoning before its final answer; in the Playground you can switch reasoning on or off to compare results.
How to Use Claude Opus 4.1 on ModelFold
- 1
Step 1: Try it in the Playground
Open the Playground at the top of this page, type a prompt and see how Claude Opus 4.1 responds before writing any code.
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Step 2: Create an API key
Sign in to ModelFold and create an API key in the console. Keep it secret and send it as a Bearer token.
- 3
Step 3: Send a request
Call POST https://modelfold.ai/v1/chat/completions with "model": "claude-opus-4-1" and your messages. Existing OpenAI-compatible SDKs work by changing the base URL and key.
- ✓
Step 4: Ship and monitor
Integrate the response into your product and check token usage and spend for every call in the console logs.
What You Can Build with Claude Opus 4.1
AI coding assistants
Generate, explain, debug and refactor code, review pull requests and work through multi-file changes in developer tools and IDE plugins.
Autonomous agents
Build agents that plan multi-step tasks, call your tools and APIs, and keep working toward a goal across long sessions.
Analysis and complex reasoning
Work through research questions, data interpretation, planning and other problems that need careful step-by-step reasoning.
Screenshot and image understanding
Read screenshots, charts, diagrams and photos alongside text — for UI review, visual QA or turning images into structured data.
Frequently Asked Questions
What is Claude Opus 4.1?⌄
Claude Opus 4.1 is an updated version of Anthropic’s flagship Opus model, with improved performance in coding, reasoning and agentic tasks.
Which inputs does Claude Opus 4.1 support?⌄
Claude Opus 4.1 accepts text, images and files (such as PDF) and returns text. Through ModelFold you can send text and images (OpenAI-style image_url content); in the Playground you can also attach documents, which are converted to text.
How long is the context window of Claude Opus 4.1?⌄
Up to 200K tokens, shared between your input and the model’s output.
Does Claude Opus 4.1 support function calling?⌄
Yes. Claude Opus 4.1 supports tools / function calling through the standard tools parameter of the chat completions API.
How is Claude Opus 4.1 billed on ModelFold?⌄
Pay as you go by tokens: input and output tokens are charged at the per-million-token prices shown on this page. There is no monthly fee, and failed requests are not charged.
How do I call Claude Opus 4.1 through the API?⌄
Send a POST request to https://modelfold.ai/v1/chat/completions with "model": "claude-opus-4-1", using your ModelFold API key as the Bearer token.
| Input | 3600 credits 1M tokens≈ $18.00 |
| Output | 18000 credits 1M tokens≈ $90.00 |
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 →AI Agents · Claude Code / Cursor / Trae →curl https://modelfold.ai/v1/chat/completions \
-H "Authorization: Bearer $MODELFOLD_API_KEY" \
-H "Content-Type: application/json" \
-d '{"model":"claude-opus-4-1","messages":[{"role":"user","content":"Hello"}]}'