Bulk Rename Utility (free and licensing options)
A Windows application that does exactly what it says it does. Its long list of features includes renaming photos via EXIF data, renaming MP3 files using ID3 tags, renaming files and folders, and much, much more.

Coda (free)
Is it a document or is it an app? It’s a document that behaves like an app that you can customize to fulfill your needs. Much more simple than Airtable and easier to use. Templates are available for project management, sales & marketing, HR, event planning, personal, productivity, design & products, health & self-improvement, education, and more. Available on Android and iOS.

file.io (free)
Ephemeral file sharing. Convenient, anonymous and secure.

HelloSign (free and paid options)
Secure and legally binding electronic document signing. By Dropbox.

IrfanView Graphic Viewer (free for non-commercial use)
You could use another file viewing program for Windows, but why would you? This classic is frequently kept up to date and is simply the best. It’s always handled graphics, but it now manages video and audio files, too!

PDFfiller (paid options)
Create and edit PDFs online: convert and compress, split and merge, convert from pdf, convert to pdf; host forms online; eSign; and your data is protected with US federal and EU compliance standards.

PDF-XChange Editor (one time licensing fee)
The smallest, fastest and most feature-rich free PDF viewer/editor on the market.

Proof of Existence (free)
The original Blockchain notary service, offering instant, anonymous, distributed, and secure proof of existence for any document, agreement, or contract.

Rclone (free)
Syncs your files to cloud storage with preserved time stamps, checks for missing files and newer files versions, can do one-way syncs.

Vertex24 (free)
So many templates for Microsoft Word and Excel, Open Office, and even Google Sheets. Templates for budgets, business, calendars, data analysis, debt payoff, education, financial calculators, financial statements, flyers, health charts and logs, home and family, inventory, invoices, letters, lists and to-dos and checklists, project management, resumes, schedules, timelines, and so much more.