I've been using PostBuilder (used to be called gramspacer) for several months now and I use it almost every single work day. PostBuilder makes it super convenient for organizing and planning content for my Instagram pages and the founder is very responsive if you have questions or if there's ever an issue. I definitely recommend them!
Instaspacer - Putting the spaces back into Instagram
2016bestnine - Your best nine Instagram pics from 2016
PicMerger - Merge photos side by side, create beautiful photo collages, customize your content with built-in photo editing tools, and more
The Twayback Machine - View your friends' old tweets for fun and trolling
StoriesStudio App - StoriesStudio allows you to take a long video and cut it down into separate clips that can then be uploaded to Instagram stories, WhatsApp, TikTok, and more.
PastBook - PastBook is an online service that allows you to create your own beautiful photobooks and share them with friends and family.