I would say anything in the video / 3D / imaging service platforms always have a lot of things left to be desired for.
Anything that potentially touches FFMPEG basically
I can name a few examples that I still think need improvements
- Online gif editors
- Video editing / clipping
- Background image editing / online photoshop equivalents
- Better alternatives than lucidpress / adobeIndesign for catalog page / brochure creation
- Machine learning / deepfake online tool, this is all driven client side mostly
- Pretty much anything client side thats not yet server-side is open game I would say
- PDF markup tools could be better for online-based services, especially for architectural design
- CAD-based online programs for retails so customers can DIY build their own warehouse or layout schemas is lacking
- Better online RDBMS. Currently, there's just airtable, its lacking some core features like refential integrity
- Integrating space-repetition learning in most educational based services (lynda.com,pluralsight, etc)
- Managed ecommerce cart / hosting services. Its a well understood problem that should technically be easy for a client to do.
Again, I would say, almost every profitable service touches some form FFMPEG for video / image editing / 3D is definitely still out there. There's such a huge untapped market out there combining all of theses services in one package.