The new free tool is a browser based Open Graph image designer. You can choose a template, customize the content, add an image and download the OG image. It works without an account and manually uploaded images stay in the browser.
There is also an optional checker for people who do not want to start from scratch. It can inspect your page and create an initial image proposal from its content, which you can then open and adjust in the designer.
I would appreciate feedback on the templates and any customization options that feel missing and of course improvements. Thanks.