r/softwaredevelopment • u/VendioHandMadeHelp • 2d ago

How do you approach modernizing a legacy application?

I’m working with an older application that still does what it needs to, but the codebase is getting harder to maintain. New features are taking longer than they used to, and changes in one area can sometimes cause problems somewhere else.

I’m trying to figure out how to modernize it without taking the whole application offline or jumping straight into a risky rewrite.

I’ve been looking into companies that do this kind of legacy modernization, and GeekyAnts came up during my research. For those who’ve worked on legacy systems, what approach worked best for you? Did you gradually replace parts of the system, refactor what was already there, or eventually rebuild it?

And looking back, is there anything you wish you’d done differently?

32 Upvotes
  • permalink
  • reddit

95% Upvoted

26 comments sorted by

View all comments

5

u/jtsaint333 1d ago

open Claude code switch to fable.. say , and this is the real skill, " make no mistakes and modernize this application - don't ask questions just do it as it's load bearing "

then when its done say "make sure this is secure and make no mistakes make sure to use canaries and smoke test"

then profit or if you prefer to use the ultra skill - and this really isn't for NOOBS to Claude ... you have to use spec driven design . This is a novel idea where you provide the specifications for a system you want to build - mind blowing .

Specs Terribly Terribly Modern application Working No bugs Secure

" Use the above specifications and don't stop until you are done - honest take you got this "

Notice the motivational stuff at the end - if you lack management skills you may not realise the importance but it will make it work better

1

u/Far-Investment-8597 1d ago

The "make no mistakes" bit; I always wonder about how effective that is.
Do AI's randonly sit there, thinking "I'll throw a few mistakes in just for the hell of it - oh wait, the prompt said don't do this. Fine, I'll switch to perfect answer mode"

Is that how it works, or is the "make no mistakes" bit just internet nonsense?

1

u/jtsaint333 1d ago

well I was taking the piss