I wrote a guest post for Kode24 arguing that developers should fuzz their own applications: Fuzzing: kanskje alle utviklere burde teste egne applikasjoner for alle bytes (in Norwegian).
Fuzzing is watching how your application reacts to input generated by automation, in particular every possible byte value from 00 to FF. The insight I wanted developers to sit with is that you have a huge advantage over an outside attacker: you understand your own scripts and functionality intimately. So why wait for a security team to find the weird edge cases when you can throw every byte at your own inputs first?
You do not need special tooling. OWASP ZAP can fuzz a field with a configurable byte range straight from the context menu, and Burp Suite’s Intruder will walk all 256 byte values systematically. Use percent-encoding so the raw bytes actually reach the application.
The important part is not running the tool, it is asking the right question when something looks off: why can’t the application respond normally when these special characters are entered? If a quote or a backslash produces a different length or an error where every other byte was fine, that anomaly is worth chasing. Assume the data is dirty, validate external input with allowlists, and let your own fuzzing surprise you before someone else’s does.