What are the mistakes / error one can do while creating a website ?

PS : Need to find out errors on existing website as a part of project

"Closed as too broad."

This is a vague question, tbh.

Are you talking frontend or backend?

@Stuxnet I agree

@Stuxnet need to know the security issues mainly , like the max ping limit test , regex etc .

PS: would have edited in the rant itself but its not allowing . Sorry for such a broad question.

@garuna oh yes you wouldn't be allowed to edit the rant after 5 mins

@garuna There's SQL injections. Those are bad lol.

@Hu-bot0x58 savage af

@Stuxnet what if your database is not framed in sql

@Hu-bot0x58 tried and found this

https://owasp.org/index.php/...

but i hate reading , this does not contain any image even

@Hu-bot0x58 from internet I got various answers but I wished to know the errors where I would have scratched my hair for two weeks to find out a sample error leading to some major security/ interface issues

Look up owasp. Nice list of basic things your site shouldn't be vulnerable for

I checked these some time ago, not brilliant, but they will do, check it out:

https://reddit.com/r/...

https://google-gruyere.appspot.com/...

xss where you execute some script by adding some text in input.
Persisted xss where you do the same but effects are stored in back end
Csrf execute some input from link
Dos denial of service effects bandwidth of website
sql infection inject text to execute arbitrary SQL queries
Session hijacking using cookies
...
I guess most standard automatic tool is burpsuite
And to learn more use owsap juice shop it is a juice shop website with numerous loop holes which you can exploit and learn more about security practical