You can link to pre-populated chats

How can I give someone a link to a chat, where the first turn is pre-populated?

ChatGPT: Use the "share" function

Start a chat, submit the first message, then use the "Share" button to get a link.

People who view the link can then continue the conversation in their own account (example).

You can append a model query parameter to specify the model you want to use:

• https://chatgpt.com/share/68a5f7f7-5564-8008-9eab-46c8b234be14?model=gpt-5-thinking

ChatGPT & Claude: use the querystring

To link to a "new chat" with the first turn pre-populated, you can do:

• https://chatgpt.com?q=Hey+ChatGPT
• https://claude.ai/new?q=Hey+Claude

You can pass about 750 words into ChatGPT, or 1500 words into Claude.¹

With ChatGPT, you can specify the model:

• https://chatgpt.com/?q=Hey+ChatGPT&model=gpt-5-thinking

Issues with the querystring approach:

• These features are undocumented. They have been available since early/mid 2024. But, they might break unexpectedly.
• If the user is not already logged in, they'll be prompted to login then redirected to a new chat without the pre-populated text.
• You'll want to URL encode the text.