This very simple little web app allows you to draw circles on top of a Google Map, with a radius that you specify.

• click: Place a circle
• Ctrl + click: Place a pin
• right-click: Remove

Try it out.

This tool supports the following optional query parameters:

• lat: Viewport center latitude
• lng: Viewport center longitude
• z: Default zoom level
• r: Default circle radius
• u: Default circle radius units