"Hi! I'm so excited to share this with you - I just started using a new app to connect with other moms in our area and it's been really fun! The best part is, it's totally free! Would you like to join me and see what you think?"

Also, here are some variations:

"Hey! One of my mom friends invited me to try this new matching app and I thought of you! It's free and seems like a great way to meet other moms in the area. Want to give it a shot?"

Let me know if you want any modifications!