Most websites are developed without sounds and if there are any sounds inside then they're most likely coming from some videos and they're not single click-like or notification-like sounds, known very well from desktop applications. The same goes for many mobile application, as sounds are mostly found in mobile games.
But, if you do need something like click sound, tick sound or any notification-like short sound, then this article lists some most famous, yet free sites, from where you can get as many such sounds as you need.
No code here, sorry! Refer to other sources on how to embed sound within website or mobile application.
There is a large number of sites that are offering free / public domain or attribution-like "beep" sounds, i.e.:
There are also many free on-line services and programs that lets you add speech to application or website easily. Due to my requirements, list is oriented toward Polish language:
TTS: On-line services
TextToSpeach is just amazing !!! It offers six languages and seventeen different speakers, speaking really nearly-natural voices and it generates
*.mp3 files and whole service looks completely free! The only pain is, that it of course doesn't support Polish and speaks this language (by English speakers) semi-understanable.
Listen is just a tiny alternative, based on Google's text to speech API, offering only one language and voice.
Freenuts offers a small catalog of top 10 websites to convert text to speech online for free. Worth testing, but if they don't support Polish, I doubt, they can beat TextToSpeach.
Freeware Files and Software Informer has similar catalog like above, but for downloadable and installable software only. BTW: I'm shocked, this is the first time, when mother fuckers behind Software Informer become useful in any other meaning than being just stupid, irritating search results stealer!
Syntezatorek is the only website (Polish naturally) in this listing to offer Polish TTS solutions. It has a list of both on-line services, downloadable software and even offers own program.
But since entries are looking very, very old (below mentioned IVONA software has Expressivo synthesizer as "newest" product, and it was released like five or even ten years ago), so most of these links may be dead, software useless or there could be a lot of trouble getting info about license.
So, big thumb up for having anything in Polish, but expect some troubles ahead.
Some last words
At first, I was thinking about using real-human voices, from IVONA.com, but since this Polish company was acquired by Amazon, their management's heads has been triple times fucked by a nasty dick. Offer they sent me was creazy (five numbers -- tens of thousands of PLNs -- for a small buck of sounds and speeches). So, I decided to screw them.