Do I need a website to use Donorbox?

No, you don't need to have a website to use Donorbox. 

Every Donorbox donation form you create will get you a stylish donation page, hosted on our secure SSL-enabled servers. It is completely free, and you can have as many as you need. 

You are allocated a dedicated URL to your donation page, which you can also edit if needed. And it will always be available to you until you decide to archive your campaign. When a donor clicks your campaign's URL, they'll be taken directly to your Donorbox-hosted donation page. 

To locate your URL, log into your Donorbox account, and go to the Campaigns page.

On this page, you will find the campaign that you want to link to. That form's URL will be displayed underneath the title, as a blue hyperlink:

You can read more about Donorbox donation pages here.