Good apps to make invitations are Evite, Canva, Smilebox, Invys, Punchbowl, and Paperless Post.
There are a lot of free online E-Invitations that are customizable with invite designs.
Christmas and birthday invitations can be obtained online.
Free online invitation maker is easy to learn, quick and fun. Typeform templates are available along with free online party invitation template.
Smilebox.com has invitation maker information there.