Number Base Converter — Decimal, Hex, Binary and Octal
The same number written in a different base is the same number, and recognising that is harder than it sounds when you are looking at a colour value in one place and a decimal in another. This converts between the bases that actually turn up in web work: decimal, hexadecimal, binary and octal.
When it helps
Because interfaces disagree about which base to use for the same thing. Colours are hex in CSS and decimal in image tooling. File permissions are octal. Character codes are hex in escape sequences and decimal in entity references. Comparing a value from one context with a value from another means converting one of them, and doing that mentally under time pressure is how off-by-one errors get introduced.
Worth running automatically
The conversion is momentary; what benefits from automation is consistency. Where the same value is expressed in different bases across configuration files, generating them from one source rather than maintaining both is what prevents drift. Beyond that, the useful continuous check is on the effect rather than the value — verifying that a rendered page actually uses the colours or applies the permissions the configuration intended.
What you get out of it
Removes a small, repetitive source of error from work that crosses interfaces with different conventions. Cheap to use, and it avoids the mistake that is hardest to spot afterwards.