Do I need to define firebase security rules for my app which stores all stickers image in database and its url in cloud firestore?

I am storing images in firebase storage and its url and download count in cloud firestore under imageurl and downloadCount field respectively. I am fetching all the images from firebase and making them available for download inside my app. Everytime an user downloads an image I am increasing its download count by one. For this I have to set my cloud firestore read and write rules to if true. I am not authenticating any user. I have set my firebase storage as read to if true and write to if false. I am confused what rules to set in my case as my app requires no authentication neither there is any way to upload any data or acess data of other user, it's just a simple image downloading app which fetch images from firebase and display it for download. Can someone guide me if there is any issue with the firebase rules that I have set for my app or its okay for my use case?

If security is an important prospect for you then please follow these :

Adding Firebase rules for your app is important. If you don't want any authentication in your app (as it will save some time of user to get those image) better to have at-least the anonymous authentication service of Firebase and authenticate each user in the background. Here you will find the Anonymous Auth doc : https://firebase.google.com/docs/auth .

To know how to set up security rules follow this medium blog, It explains clearly about how we can set-up rules in order to protect our data. For Firestore click here

Any user who has the access to your database URL can send unnecessary requests and may cause blocking or costing to your account.

So its not mandatory to set-up rules, It depends upon your requirements.

The answer is, My app does not involve authorization or allow any user to upload to the database/firestore or allow access to any other information other than images,downloadCount and Image name, I dont need to define any strict security rules to my firebase. Since only the download count is increased by downloading the image,the best practice is to define rule that will allow only the increment of downloadCount field by updating the write permission to the following:

match/{document=**} {
allow write: if request.resource.data.keys().hasOnly(['downloadCount']);
}

The above code ensures no other field of document is writable except for the downloadCount when user downloads the images.

If your app requires any form of authorization or uploading or editing into your database then you must set the strict rules to make yours as well as users data safe.