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!
Kamua - Automate video resizing, cut-downs & captions for social
Instaspacer - Putting the spaces back into Instagram
Node Video - Most powerful video editing app ever
PicMerger - Merge photos side by side, create beautiful photo collages, customize your content with built-in photo editing tools, and more
Flixier - Flixier Pro is an online video editor that speeds up your workflow with 1 minute rendering on any device, streamlined communication and collaboration features and plenty of cloud storage.
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.