I use https://insighttimer.com/ which is free.
I started out with headspace, it was worth it because it holds your hand and got me to start meditating daily. Once I got comfortable with meditation, I switched to insight timer.
I've heard a lot about 'Calm' working wonders. It's available on Google Playstore and Appstore.
Being a guy who grew up with a Yoga Guru at home i dont think there is need for Apps for meditation.
Some people use soothing Music but i recommend using none of it. You just need to concentrate within yourself.
If you want to try you can try Head space app and Music.
Insight and Headspace have been mentioned. There's another app that I feel is great (especially if you're not into the woo woo of meditation). It's called 10% Happier. In fact, their slogan is "Meditation for fidgety skeptics"
It's a great app that really takes all the fluff out and simply give you guidance on quieting your mind without distractions. Here's a link to their website https://www.10percenthappier.com/ They also have a podcast and many other free resources to help you get started.
Fitbit has some extensions that I've used which is great. If you have one I'd highly recommend it
I've used Headspace App and found it to be a great resource for guided meditation.