GrovePi+ are compatible with Pi 3, please check the details from Dexter blog.
GrovePi+ is a system with 15 Grove 4-pin interfaces that brings Grove sensors to the Raspberry Pi. It is the newest version compatible with Raspberry model B/B+ and A+ perfectly.
GrovePi+ is an easy-to-use and modular system for hardware hacking with the Raspberry Pi, no need for soldering or breadboards: plug in your Grove sensors and start programming directly. Grove is an easy to use collection of more than 100 inexpensive plug-and-play modules that sense and control the physical world. By connecting Grove Sensors to the Raspberry Pi, it empowers your Pi in the physical world. With hundreds of sensors to choose from Grove families, the possibilities for interaction are endless.
Please be notice: The Raspberry Pi board is not included.
Step 1 - Slip the GrovePi+ board over your Raspberry Pi
Step 2 - Connect the Grove modules to the GrovePi+ board
Step 3 - Upload your program to Raspberry Pi
Step 4 - Begin taking in the world data
Getting started with GrovePi+
Programming the GrovePi+
More Grove Sensors Compatibled with Raspberry Pi