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How to Use Claude Sonnet 4.5 Across Tools and Platforms

BlogsClaude SonnetAI CodingIDE IntegrationAugment CodeAbout 3 min

How to Use Claude Sonnet 4.5 Across Tools and Platforms

Claude Sonnet 4.5 is a large-context AI model introduced in September 2025. With a context window up to 1 million tokens (beta) and improvements to coding, reasoning, memory management, and tool use, Sonnet 4.5 is especially suited for software development and autonomous agents.
The model is accessible through multiple channels—including IDE integrations, APIs, and web/mobile apps. This guide explores every possible way to use Claude Sonnet 4.5 and highlights free or trial options.

Key Improvements in Claude Sonnet 4.5

  • Context length: Supports 200k tokens by default, with a 1M token beta option.
  • Enhanced coding skills: Stronger reasoning, debugging, and refactoring capabilities.
  • Autonomous agents: Expanded support for task automation via Claude Code and Augment.
  • Memory and context editing: Persistent memory, checkpoints, and better long-document handling.
  • Knowledge cutoff: April 2025, ensuring more recent awareness.
Claude Sonnet 4.5 Capabilities
Claude Sonnet 4.5 Capabilities

Note: This image is an example of Claude Sonnet 4.5's capabilities in action.

Using Claude Sonnet 4.5 in Different Environments

1. Augment Code

  • Sonnet 4.5 is now the default model in Augment Code.
  • Ideal for autonomous coding agents that can write, test, and refactor software.
  • Supports context sharing, team collaboration, and workflow automation.
  • Plans & Trials:
    • Offers a Community Plan, considered one of the most generous free AI agent plans.
    • Paid tiers include more user messages and advanced agent controls.
    • New users also get 14-day free trials across paid plans.

2. Claude Code

  • Built directly by Anthropic to allow AI-assisted coding inside controlled environments.
  • Features autonomous task execution with code execution, debugging, and file creation.
  • Often bundled in enterprise or Claude for Teams setups.
  • Recommended for developers needing reproducible environments and tighter safety controls.

3. Cursor IDE

  • Cursor is a coding IDE integrating Claude Sonnet models.
  • Provides AI-powered autocomplete, inline explanations, and debugging assistance.
  • Users on Pro/Team plans can select Claude Sonnet 4.5 as their coding engine.
  • Best suited for real-time coding and developers looking for a VS Code-like AI IDE.

4. APIs & Integration

Official Anthropic API

  • Available via Claude Docs with claude-3.5-sonnet and claude-4.5-sonnet endpoints.
  • Integrates with IDEs, workflows, or backend apps using REST or SDKs.
  • Pricing typically starts around $3 per million tokens input and $15 per million tokens output.

OpenRouter

    • OpenRouter acts as a unified API gateway, exposing Claude 4.5 alongside OpenAI, Mistral, and others.
    • Benefits include easy model switching, per-request model choice, and often free credits for new sign-ups.
  • Great for developers who want flexibility beyond Anthropic’s direct API.

Cloud Providers

  • Sonnet 4.5 is also integrated into AWS Bedrock and Google Vertex AI.
  • Allows enterprise-scale deployment with usage billed through your cloud account.

5. Claude Web App & Desktop App

  • Claude.ai offers direct browser-based access to Sonnet 4.5.
  • Supports chat, document uploads, spreadsheets, PDF handling, and file creation.
  • Desktop apps for macOS/Windows provide the same features with native integration.
  • Plan options:
    • Free tier (limited usage, usually with Claude 3.5 or capped Sonnet access).
    • Claude Pro ($20/month) — unlocks higher usage, priority access to Sonnet models.
    • Claude Team & Enterprise — collaboration, longer context, and file creation tools.

6. Claude Mobile App

  • Available on iOS App Store.
  • Brings Claude Sonnet 4.5 to smartphones with chat, coding, and file support.
  • Syncs with web and desktop accounts for continuity.
  • Supports free and Pro tiers depending on login account.

Free Usage & Trials

  • Claude Web App (Free Plan): Limited daily messages, usually Sonnet 3.5, but occasionally Sonnet 4.x depending on availability.
  • Claude Pro ($20/mo): Unlocks Sonnet 4.5 consistently, higher message caps, and faster access.
  • Augment Code: Free Community Plan plus 14-day free trials on paid tiers.
  • OpenRouter: Many new accounts receive $5–$10 free credit for testing Sonnet 4.5.
  • Mobile Apps: Free plan mirrors the web tier, Pro available via in-app purchase.

Choosing the Best Option

  • For Developers: Use Cursor or Augment Code for IDE-level integration.
  • For Teams/Enterprises: Use Claude Code, Anthropic API, or cloud integrations (AWS, Google Vertex).
  • For Everyday Users: Start with the Claude web app or mobile app.
  • For Experimentation: Try OpenRouter for free credits and multi-model flexibility.

Conclusion

Claude Sonnet 4.5 is Anthropic’s most powerful model yet, excelling in coding, reasoning, and context-heavy tasks. Whether you’re a developer, enterprise, or casual user, there’s a pathway to integrate Sonnet 4.5 into your workflow—through IDEs like Cursor, agent platforms like Augment, direct APIs, or the official Claude apps. With generous free tiers and trial credits, anyone can start experimenting today.

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