123FormBuilder is an online form builder with file upload functionality. Users can collect files from their respondents through form submissions by adding File upload fields to the form.
All supported file extensions of the File upload field are located in the Validation section, within the field’s options. To allow only certain file extensions to be uploaded, at File types accepted use the dropdown list to check the extensions you want to use.
Moreover, if you need a new file extension, simply click on Add.
Here is a list of the file extensions that the File upload field supports:
Additionally, you also have the option to reject certain files from being uploaded on your forms. Just check the File types forbidden dropdown list and tick the files that won’t be accepted on the form.
Similar to the File types accepted list, here you can also Add new extensions that your form shouldn’t accept.
When your form respondents upload a file extension that hasn’t been accepted, they will encounter the following error message:
To prevent them from receiving this error popup message, we recommend mentioning the accepted file types in the File upload fields Instructions box.