Postly

Postly used to be a relatively good piece of kit, but you can no longer save posts as drafts which renders it pretty much useless in my opinion. It's possible to schedule posts, so if that's how you work this could be a good fit. If you prefer to first create posts, without committing to a date/time to post, I'd look for an alternative I wish I was still within my 60-day refund period, but sadly this isn't the case.