Vibe coding fails quietly: how to know if your app actually works
Your vibe-coded app is live. It loads. Pages render. You click around and nothing explodes. That feeling of relief is exactly the problem.
In Part IV of his five-part series on vibe coding for non-technical founders, Matt Blumberg on The Startup CEO blog makes a point worth sitting with: this kind of software rarely crashes outright. It fails plausibly. A broken feature is cheap because you can see it. A plausible failure, something that looks like it worked but didn’t, is what costs you a month.
️ The core testing problem for non-coders
When a professional developer reviews code, one of their jobs is to stop and ask, “but what if someone’s hostile?” Vibe coding skips that person entirely. The method gets a real product onto the internet and mostly working, but it also ships exactly the kind of security gap a trained reviewer would catch on sight.
That gap doesn’t announce itself. It just sits there until someone finds it the wrong way.
Why the written record matters more than you think
Blumberg points to the spec and decision log from Part II of the series as the tools that earn their keep at this stage. His accidental experiment makes the case: same builder, same month, same tools, two different projects. One had the written record. One didn’t. The difference in how quickly problems could be diagnosed and fixed was not subtle.
When something goes wrong and you need to check a fix against the real code rather than trusting a summary, the decision log is what tells you where to look. Without it, you’re debugging a black box you don’t understand.
How to work through problems when you find them
Blumberg describes the approach that worked for him: three focused work sessions, one batch of problems at a time, checking each fix against the actual code rather than accepting the AI’s word that the fix was complete.
- Batch your problems. Don’t try to fix everything at once. Group related issues and work through them in sequence.
- Check against real code. Don’t trust a summary. Have the AI show you the actual change and verify it landed where it was supposed to.
- Use focused sessions. Context degrades over long conversations. A fresh session with a clear, scoped problem gets better results than a sprawling multi-hour debugging thread.
The Bedrock case
Blumberg’s own product, Bedrock, took 27 days from start to launch. He’s clear that launch wasn’t a victory lap. It was a minimum viable product release, after which he’s been building and tweaking continuously. That framing matters: the goal of testing isn’t to achieve perfection before shipping. It’s to know what state your product is actually in at any given moment, so you can make deliberate decisions about what to fix next.
The honest takeaway
Vibe coding is a legitimate way for non-technical founders to get software into the world. It is not a way to skip the work of understanding what your software actually does. The testing habits Blumberg describes aren’t optional polish. They’re the difference between a product that works and one that merely looks like it does.
The full series, including Parts I through III on basics, setup, and the build, is on The Startup CEO blog.
I’m founder of BizStack at Cagri Sarigoz LLC and a passionate advocate for entrepreneurs.
With over 14 years in tech, marketing, and AI, including my role as Head of SEO at CitizenShipper and co-founder of TaleBot at Intale AI, I’m dedicated to sharing genuine, useful product insights and tips.
At BizStack, I aim to cut through the digital noise to provide clear, actionable advice.
And more than all else, I’m a father to a (always) little girl and a husband.
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