who is the developer of iPhoto

Apple is the developer.

Starting with macOS Yosemite and moving forward, iPhoto is no longer a thing.

The new app for photo management is Photos.

Photos User Guide for Mac - Apple Support

kentdoss wrote:

I installed Catalina to my Mac Pro and no longer have the iPhoto App available .What can I do?

? iPhoto was a digital photograph manipulation software application developed by Apple Inc. It was included with every Macintosh personal computer from 2002 to 2015

Iphoto was replaced by Photos —

macOS Mojave 10.14 was the last OS to support the app, as the release of macOS Catalina 10.15 on October 7, 2019, does not support iPhoto.

You should of transitioned the software before upgrading to Catalina...

You can launch Photos.app holding the Option key and see if you have an option to select your old photo library