The best alternatives to Flashbomb are Gantt, Photoshoot, and Mfile. If these 3 options don't work for you, we've listed a few more alternatives below.
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Gantt.io creates amazing Gantt charts for you in no time. Beautiful templates, a very intuitive and efficient interface, multi-user editing, time-travel as well as a high-res export function allow you to create THE chart that will convince your audience.
Files is a beautiful single-file PHP file browser and manager that can be dropped into any dir on your server, instantly creating a gallery of files and folders. It supports all file types and allows you to preview images, video, audio, text and code.