Gift certificate plugin/integration

Hi all,

I was wondering if anyone may have had experience using a gift certificate plugin or integration on their marketplaces that they thought was good? What I'm aiming to do is:

1) Enable sellers to sell gift certificates, which would be digitally generated and emailed to buyers at the time of purchase.

2) Potentially offer 'site-wide' gift certificates, that a person could use across the whole site (i.e. with any seller), and input their code at the time of payment. This option may be a bit more complex and could be developed later potentially.

I've got ok javascript/jQuery skills so thought there might be a plugin or something that could work with Paypal/Stripe, or potentially a separate application all together. 

Any thoughts would be much appreciated :)

GL