Pay platforms like Zelle and Venmo

What should I know about being self-employed and using free pay apps like Zelle and Venmo?

Self employed

Adding on to this question to mention PayPal and Stripe

 

?? what do I need to know about the differences between paid services vs. free services when collecting payments from my coaching/training clients? And how that affects recording for taxes. 

 

Thanks bunches for sharing your time and expertise