Images must be square and between 180×180 and 360×360 pixels. Maximum size is 1MB.
Images shouldn't include words like "ad" "promo" "advert" etc in their URLs. Most adblock systems flag it and it'll cause the widget to disappear.

Add the iframe widget on your site first, publish the page, and only then submit. Widget must be fairly prominent. If user has to go to a deep page or scroll through a billion webrings, I might reject your submission.

Site must have content. Get some cool things, writings, projects, arts you've made or whatever; don't submit if it's just an about page and a blog with one post saying "hi i made a website", thanks.

Once submitted, I will review and approve or reject your site. I will usually do it within 24 hours, but sometimes it might take longer. If your site hasn't been approved after a week, it's likely that it was rejected. You may resubmit after 3 months.

Submit