I’m seeing established bootstrapped SaaS companies rewrite their entire platforms this year using agentic coding — and ship new, modern platforms 10X faster than the painful rewrite slogs of 10 years ago.
Successful software companies that have been around 10 years all face the legacy code problem:
– Scrappy engineers built the first app years ago
– More engineers piled on and kept building features
– All your devs complain about the code and the bugs
– Bug fixing creates more new bugs
– Your roadmap is 50% fixing and 50% painfully slow feature dev
The dreaded rewrite slog or major refactor year isn’t new. These have been going on in almost all software companies that got big enough and old enough.
A real rewrite used to kill 2-3 years of the roadmap — and the business. Which most VC-funded, public, and even bootstrapped software companies couldn’t afford.
But now we have AI hitting hard.
– New competitors are coding fast and iterating on customer feedback
– Your old data schema and API foundations aren’t ready for AI yet
– You may have AI features in your app that need major UX changes
I still haven’t seen any experienced devs pointing Claude Code or Codex at their millions of lines of legacy code to “build us a modern version with these features, schema, and business logic.”
But I have seen AI-savvy CTOs and senior devs create the right frameworks, scaffolding, and testing agents to rebuild big apps–in months, not years.
Months, not years. 6 months vs. 3 years is HUGE.
I have done the 3-year rewrite running a $50M software company, and it was one of the most painful things I ever did. It was supposed to take half that time, of course.
Rewriting faster with agentic coding isn’t for every software business or every situation, and it’s not just for “small and non-mission-critical” apps.
It’s also not the founder vibe coding a new UI over the weekend and expecting to ship it in production soon. No-code prototyping is not scalable agentic development.
After that ordeal, you get back to the bigger challenges:
– Deciding what to modernize in the user interface and what not to change. Most customers will complain if you change too much.
– Dealing with the “other 90% of the work” with edge cases and refinements.
– Deciding what is actually important and useful for customers now that you can build anything faster.
It’s not for everyone, but rewrites can be 10X less painful than they used to be.
And 10X less expensive. You don’t need outside funding to do this; you need the right founder, dev, and product leaders, and senior AI-experienced coders. Savvy founder-led is more important here.
My prediction is that 50% of established SaaS apps will be substantially rewritten using modern agentic coding in the next few years, in small or large chunks.
When you can’t beat ’em, join ’em.
