Free app to allow Affiliates to track number of sales with their discount code

[Majj]

I run my business on Instagram. I started an affiliate program by sharing custom discount codes to each person/influencer that they can share with their network.

Basically, the discount code gives the influencers' network 10% off our products, and in return I pay the influencer a commission for every sale made with his discount code.

Is there a free app, to mainly just allow influencers to track and see how many orders were made using his/her code?

Instead of me going to the Discounts page, check how many times it's used, screenshot and share it. 

Thank you

[fialuna]

I haven't' used it, but have a look at Shout Out. It isn't free. It's $39 a month, but has good reviews. Are you seeing good results from this strategy? I'm just looking at doing this myself.