Deploy and test an Ubuntu VM for free (dies after 20 minutes of inactivity).
Has a browser file explorer, text editor and terminal. Allows ssh connections.
Free server. Low space and few tools (php, mysql, cron and ftp), but it's free!
Free website hosting. Basic, but neat interface.
[Have I been Pwned](https://haveibeenpwned.com/)
Check if you have an account that has been compromised in a data breach
Check the state of your browser's TLS/SSL with How's my SSL or SSL labs
Inspect HTTP requests:
These allow you to inspect your HTTP requests, such as POST: Request Bin, Henry's HTTP Post Dumping Server, httpbin(1)
[You Pronounce It](http://youpronounce.it/)
Find the English pronunciation of words with youtube.