How to use Claude Sonnet 4.5 from Anthropic with API Key

Learn how to access and use Claude Sonnet 4.5 with your Anthropic API key through TypingMind. Get started with this powerful AI model in minutes.

Claude is a next-generation AI assistant developed by Anthropic, featuring a family of state-of-the-art large language models trained to be safe, accurate, and helpful. The latest models include Claude Sonnet 4.5 (the world's best coding model with advanced agentic capabilities) and Claude Opus 4.1, both offering hybrid reasoning modes, 200K token context windows, and sophisticated vision capabilities.

Key features include tool use for external API integration, code execution environments, multi-step workflow automation, files API, persistent memory management, and enterprise-grade security with deployment on AWS Bedrock and Google Cloud Vertex AI.

Claude excels at complex reasoning, code generation, visual data interpretation, customer support, and building autonomous AI agents with natural, human-like conversations.

Official Documentation: https://docs.anthropic.com/en/docs/about-claude/models

Claude Sonnet 4.5 Overview

Model NameClaude Sonnet 4.5
ProviderAnthropic
Model IDclaude-sonnet-4-5-20250929
Release DateSep 29, 2025
Last UpdatedSep 29, 2025
Knowledge Cutoff2025-07-31
Context Window200,000 tokens
Max Output64,000 tokens
Pricing /1M tokens$3 input
$15 output
$0.3 cache read
Input Modalitiestext, image
Output Modalitiestext
Capabilities
File UploadReasoningTool CallingTemperature Control

Complete Setup Guide

1

Get Your Anthropic API Key

First, you'll need to obtain an API key from Anthropic. This key allows you to access their AI models directly and pay only for what you use.

  1. Visit Anthropic's API console
  2. Sign up or log in to your account
  3. Navigate to the API keys section
  4. Generate a new API key (copy it immediately as some providers only show it once)
  5. Save your API key in a secure password manager or encrypted note

⚠️ Important: Keep your API key secure and never share it publicly. Store it safely as you'll need it to connect with TypingMind.

2

Configure TypingMind with Anthropic API Key

  1. Open TypingMind in your browser
  2. Click the "Settings" icon (gear symbol)
  3. Navigate to "Models" section
  4. Click "Add Custom Model"
  5. Fill in the model information:
    Name: claude-sonnet-4-5-20250929 via Anthropic (or your preferred name)
    Endpoint: https://api.anthropic.com/v1/messages
    Model ID: claude-sonnet-4-5-20250929
    Context Length: Enter the model's context window (e.g., 200000 for claude-sonnet-4-5-20250929)
    Anthropic Endpoint URL input fieldclaude-sonnet-4-5-20250929https://api.anthropic.com/v1/messagesclaude-sonnet-4-5-20250929 via Anthropichttps://www.typingmind.com/model-logo.webp200000
  6. Add custom headers by clicking "Add Custom Headers" in the Advanced Settings section:
    x-api-key: <CLAUDE_API_KEY>:
    X-Title: typingmind.com
    HTTP-Referer: https://www.typingmind.com
  7. Enable "Support Plugins (via OpenAI Functions)" if the model supports the "functions" or "tool_calls" parameter, or enable "Support OpenAI Vision" if the model supports vision.
  8. Click "Test" to verify the configuration
  9. If you see "Nice, the endpoint is working!", click "Add Model"
3

Start chatting with Claude Sonnet 4.5

Now you can start chatting with Claude Sonnet 4.5 through TypingMind:

  • Select Claude Sonnet 4.5 from the model dropdown menu
  • Start typing your message in the chat input
  • Enjoy faster responses and better features than the official interface
  • Switch between different AI models as needed
The best frontend AI chat for claude-sonnet-4-5-20250929 via OpenRouter API KeyThe best frontend AI chat for claude-sonnet-4-5-20250929 via OpenRouter API Keyclaude-sonnet-4-5-20250929The best frontend AI chat for claude-sonnet-4-5-20250929 via OpenRouter API Key

💡 Pro tips for better results:

Frequently Asked Questions

Do I need a subscription to use Claude Sonnet 4.5?

No! With Anthropic API, you pay only for what you use with no monthly subscription. Add credits to your Anthropic account and pay as you go. TypingMind is also a one-time purchase, not a subscription.

How much will it cost to use Claude Sonnet 4.5?

Claude Sonnet 4.5 costs $3/1M input tokens and $15/1M output tokens. A typical conversation might cost $0.01-0.10 depending on length.

Can I use other models besides Claude Sonnet 4.5?

Yes! With Anthropic API + TypingMind, you can access all Anthropic models. Switch between them instantly in TypingMind.

Is my data private and secure?

Yes! TypingMind stores conversations locally (web version in browser, desktop version on your device). Anthropic handles API calls securely. Check Anthropic's data policy for specifics.

Can I use Claude Sonnet 4.5 for commercial projects?

Yes! Check Anthropic's terms of service for specific commercial use policies. TypingMind supports commercial use.