Try out the return0 Demo
Get hands-on with return0's live debugging capabilities. Install the MCP server and start debugging in real-time.
Live Demo Goal
This live demo is designed to get you up and running with the return0 MCP server in just a few minutes. You'll install the server, clone a demo repository, and start using return0's live debugging capabilities directly from your Cursor IDE. This demo showcases debugging a production app running on Vercel where some balances are incorrectly calculated and shown incorrectly. Experience how return0 can help you debug production applications in real-time by connecting to live variables, monitoring execution flow, and understanding your code's runtime behavior.
Demo Application: The demo app is running live on Vercel
https://complex-api-liard.vercel.app/Install MCP Server
Install MCP Client
Install and configure the Return0 MCP server in Cursor using one of the options below. The demo API key is already configured in the MCP configuration.
Option 1: One-Click Installation
Click the button below to automatically install the Return0 MCP server in Cursor. This will configure everything for you.
Option 2: Manual Configuration
If you prefer to configure manually, add the following configuration to your Cursor mcp.json file.
Start using return0 within Cursor
3a. Open Repository in Cursor
Open the cloned repository in Cursor IDE to start using return0 with the demo application.
In Cursor:
File → Open Folder → Select the ComplexAPI folder
3b. Start Debugging with return0
Now you can ask Cursor questions about the live application using return0's debugging capabilities:
Example prompt:
"Use return0 to find out why balances are showing up incorrectly in UI."
The return0 MCP server will connect to the live application and show you real-time variable values, execution flow, and help you understand how the code works in production.