AI API Lab

WORKBENCH / CHAT

Claude Sonnet 5.5 Anthropic

Keep the conversation going and experiment with answers and reasoning.

YOUR KEY. YOUR EXPERIMENT.
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Conversation

Ask your first question

Try writing, translation, coding, and problem solving.

QUICK START

Select an example to fill the message, edit it, then send. Switch models to compare answers.

Start a new conversation if a long chat reaches the request limit.

EXPLORE / HOW TO USE

Claude chat playground

Try Claude with your own Anthropic API key. Compare models, customize system instructions, and explore answers in a multi-turn conversation.

What you can try

  • Compare Opus, Sonnet, and Haiku across the available Claude versions.
  • Customize system instructions and explore the model’s supported thinking mode.
  • Read Markdown answers and start a fresh conversation when needed.
  • Requests use your provider’s API quota and may incur charges. Check the key, model access, and billing if you receive an authentication or quota error.

How to get started

  1. Enter your Anthropic API key and select a model.
  2. Set your system instructions and available reasoning options.
  3. Write a question or edit a quick-start example, send it, and compare the response.
  4. Example: ask the model to compare two approaches with reasons and trade-offs. Keep the question and system instructions fixed when changing the model or reasoning setting.
Explore all playgrounds →Anthropic API keys ↗