Claude Deep Think

About

Claude Deep Think lets you append a custom reasoning instruction to every message you send on claude.ai — so Claude always thinks deeply, without you copy-pasting the
  same prompt every time.                                                                                                                                                  
                                                                                                                                                                           
Features:
  - Up to 5 prompt profiles (e.g., "Deep Reasoning", "Email Writing", "Code Analysis") — switch between them instantly from a floating chip on claude.ai                   
  - Fully editable instructions — write exactly what you want appended                                                                                  
  - One-click ON/OFF toggle — disable Deep Think for quick questions, re-enable for complex ones                                                                           
  - Works instantly — no page refresh needed when switching profiles or toggling                                                                                           
  - Zero telemetry — no data leaves your browser, no analytics, no tracking, fully open source                                                                             
                                                                                                                                                                           
  How it works:                                                                                                                                                            
  1. Install the extension                                                                                                                                                 
  2. Visit claude.ai — you'll see the Deep Think chip in the bottom-right corner                                                                                           
  3. Click "Switch" to manage your prompt profiles                              
  4. Every message you send will have your active profile's instruction appended automatically, separated by a visible divider so you know it's there                      
                                                                                                                                                                           
Your instruction text is stored locally in your browser using Chrome's built-in storage. It is never sent anywhere except as part of your own message to Claude.         
                                                                                                                                                                           
Source code: https://github.com/daiict218/claude-deep-think-ext