Looking for IOS and android APP like Kijiji for classified

Hello this is for Drugstore and pharmacists users : I have done some work on the app , drugstore AI in Playstore , so we need to add it to this app as well . and the additions are : 1- classified like app similar to kijiji prob that the pharmacist can sign up to and the pharmacy can register as client , and they announce shifts that they need covered in the future . once the pharmacy posts the shifts , the user can take them or some and can see the rate being paid and message the pharmacy to take the shift and make the deal . classified will also have different Buy and sell sections related to pharmacy business . as kijiji the pharmacist will message the store that he is available and they can agree on the price for now i want to make it all FREE , but the app should have a feature to charge per posting in the future same as kijiji as well . i prefer if someone has already done this job bec it is not a new concept , but i am using it for pharmacy business . the main thing that the app can integrate my previous work and can handle future work integration