First, discover an attachment’s Id, with GetEntityById. Then supply the Id of attachment and the entity name to which the attachment was associated with (for example “Ticket”). Then call:
GET api/publicapi/getattachment?id=123&entityType=Ticket
Response object will be similar to the preview in GetEntityById, but will now include the property “Data” containing base64-encoded binary file data.
{
"Data": {
"Id": 123,
"FileSize": 35,
"ContentType": "image/gif",
"FileName": "tinygif.gif",
"Data": "R0lGODlhAQABAIAAAAUEBAAAACwAAAAAAQABAAACAkQBADs="
},
"Errors": null,
"IsError": false
}