Uploading Attachment from Non-Salesforce Users ( Site or Guest Users) through Force.com sites

I came across a question on Trailblazers community where someone asked for a way to upload an attachment to a record and it should be accessible by non-salesforce users. I won’t go into much detail about that and will focus on providing the solution.
So, you just have to follow the below-mentioned steps to make it work for you.

1. Setup a Force.com site if you haven’t already. You can get more details about this from this link.
2. Create a VF page which lets an external user upload an attachment to Salesforce record.
3. Add the page ( created in 2nd step) to the Site created in 1st step. Find more details here.

Visualforce page for Upload Attachment

You just need a VF page and here is the code gist which you can utilize and update as per your need.
Upload Attachment through Force.com sites
Happy coding 🙂