Need help with a billing solution

Hey baker folks! So I will be registering myself in FSSAI just today. Right off the bat I will need a proper billing solution because I am currently lacking that in my business. Multiple shops take baked products from me so they all will need proper bills with relevant data. For now, I am not willing to invest a huge into the billing software area. If there are free options, that would be enough for my present usecase.

Can someone kindly help out?