Great free programs and services on the Internet

There are lots of programs and services on the Internet. I love to try new ones but these are some that I use very often. Please write in the comments if there is any programs you can't live without.
Abbreviations of Internet addresses. It can be adapted to eg (If it is not used of course). I use it to give students or friends links to long URLs

2 Gb free backup of your files. By installing the Dropbox client, I only need to select a folder on my computer (mac and / or PC). Everything in that folder is stored on the Dropbox servers and ends up on all the other computers I choose to install on the client. WITHOUT needing to do anything! In addition, I have access to Dropbox on my smartphone via the Dropbox app.

Google Keep
Digital Post-it / notes.
A service that keeps track of all updates on websites, forums, newspapers, blogs etc. The best option to keep track of all RSS feeds

Take screenshots or record a small screen movie. Upload - share with you. It's ridiculously easy. A must for all teachers who want to explain something to a student asking question via the net.

After various passwords have been hacked, it has been found that many have too easy passwords and also use the same password on different websites. LassPass is the perfect cure. You just need to remember a password. The others are created by the program.

An amazing image editing program that you do not have to pay for or install. Just upload the photo. edit, save.

Send up to 2Gb files, free of charge. No advertising, without having to wait to download. However, you can only download the file once. Perfect for when the teacher or student sends large files.

You will never need another movie playback program. It takes most of the files and so far I have not found any format it cannot play.

Zip (WinZip, WinRar, 7Zip)
Actually, this should be the first thing you learn when sending files. With a file compression program (Zip program) you can pack many files in the same file, so you just need to send a file. A short manual is available here.