Your App Is Leaking: How to Debug Memory Leaks in Vibe Coded Apps

You built the thing fast. The AI wrote most of it. It works, it ships, people use it. Then two weeks later someone says the app feels slow. Then it crashes. Then you get a browser tab eating 800MB of RAM and nobody knows why.

Welcome to memory leaks in vibe coded apps. This post explains what they are, why they happen so much in AI-generated code, and how to find and fix them without losing your mind.

What Is a Memory Leak?

A memory leak is when your app holds onto memory it no longer needs. Think of it like opening 50 browser tabs and never closing any of them. Your computer slows down because the memory is full, even though you are not using most of those tabs anymore.

In code, this happens when you create something (a listener, a timer, an object) and never clean it up. The app forgets about it but the browser does not. Over time, those forgotten things pile up and your app gets slower and heavier.

Why Vibe Coded Apps Leak More

When you write code fast with the help of an AI, you are focused on making things work. That is the goal. The AI is also focused on making things work. It will give you code that runs correctly in the happy path, but it often skips the cleanup step.

Here are the most common patterns that cause leaks in vibe coded apps:

• Event listeners that are added but never removed
• Timers (setInterval, setTimeout) that keep running forever
• DOM nodes that are removed from the page but still referenced in variables
• Global arrays or objects that keep growing with no limit
• Closures that hold references to large objects longer than needed

The AI did not make a mistake. It gave you working code. But "working" and "clean" are two different things, and in a fast build you usually only check for working.

Step 1: Confirm You Actually Have a Leak

Before you start hunting, make sure the problem is a memory leak and not just a slow network or a heavy render. The easiest way to check is with your browser's built-in tools.

In Chrome or Edge:

1. Open DevTools (F12)
2. Go to the Memory tab
3. Take a heap snapshot
4. Use your app for a few minutes and do the actions that feel slow
5. Take another heap snapshot
6. Compare the two. If the numbers keep going up and never come down, you have a leak.

You can also open the Performance tab and record a session. Look at the JS Heap line at the bottom. A healthy app goes up and down. A leaking app only goes up.

Step 2: Find the Source

Now you know there is a leak. The next question is where it comes from. Go back to the Memory tab and use the Allocation instrumentation on timeline option. This records memory over time and shows you which parts of your code are allocating memory that does not get freed.

Look for objects that stay in memory long after they should be gone. Common suspects:

• Detached DOM nodes - elements that were removed from the page but are still stored in a variable
• Event listeners - attached to elements or the window object and never removed
• Closures - functions that hold a reference to a variable that holds a reference to something big

In the heap snapshot view, filter by Detached to find DOM nodes that are no longer on the page but still in memory. These are almost always a sign of a missing cleanup step.

Step 3: Fix the Common Patterns

Event Listeners

If you add an event listener, you must remove it when you no longer need it. The most common mistake is adding a listener every time a function runs, without ever removing the old ones.

Bad pattern:

function startFeature() {
  window.addEventListener('resize', handleResize);
}

// startFeature() is called many times
// listeners keep stacking up, none are removed

Fixed:

function startFeature() {
  window.addEventListener('resize', handleResize);
}

function stopFeature() {
  window.removeEventListener('resize', handleResize);
}

// Call stopFeature() when the feature is no longer needed

Always pair addEventListener with a matching removeEventListener. If you are adding listeners inside a modal, a popup, or any section that opens and closes, remove them when that section closes.

Timers

Same rule. Every setInterval needs a matching clearInterval. If you forget to clear it, the timer keeps running in the background forever, even after the part of the page it was meant for is gone.

Bad pattern:

function startPolling() {
  setInterval(fetchData, 5000);
}

// The interval runs forever, even when not needed

Fixed:

let pollingInterval;

function startPolling() {
  pollingInterval = setInterval(fetchData, 5000);
}

function stopPolling() {
  clearInterval(pollingInterval);
}

Save the return value of setInterval in a variable so you can stop it later. Call stopPolling when the user navigates away or closes the section.

Detached DOM Nodes

This happens when you remove an element from the page but still hold a reference to it in a variable. The browser cannot free it because your code still points to it.

Bad pattern:

let savedCard = document.querySelector('.card');

function removeCard() {
  savedCard.remove(); // removed from page, but savedCard still holds it
}

// savedCard keeps the element in memory

Fixed:

let savedCard = document.querySelector('.card');

function removeCard() {
  savedCard.remove();
  savedCard = null; // release the reference
}

Setting the variable to null tells JavaScript you are done with that object. The browser can then free the memory.

Step 4: Check Your Global Data

Vibe coded apps often store data in global arrays or objects. If you keep adding to them and never remove old entries, they will grow forever.

Common example: a log array that grows without limit.

const logs = [];

function addLog(message) {
  logs.push({ message, time: Date.now() });
}

// After hours of use, logs has tens of thousands of entries

Simple fix: cap the size.

const MAX_LOGS = 100;
const logs = [];

function addLog(message) {
  logs.push({ message, time: Date.now() });
  if (logs.length > MAX_LOGS) {
    logs.shift(); // remove the oldest entry
  }
}

This keeps only the last 100 entries. Old ones are dropped and the memory stays flat.

Step 5: Use a Tool to Catch Leaks Early

Manually checking for leaks takes time. You can make this easier with tools that catch problems before users notice them.

• Chrome Memory tab - already in your browser, free, and the most reliable way to find leaks
• Leak Detect (Chrome extension) - watches memory over time and alerts you when it detects unusual growth
• Playwright or Puppeteer - write a script that opens your app, clicks through it, and checks the memory size at the end

A simple memory check with Playwright:

const metrics = await page.metrics();
console.log('JS Heap Used:', metrics.JSHeapUsedSize / 1024 / 1024, 'MB');

Run that before and after a set of actions. If the number goes up every single time, something is not being cleaned up.

What to Tell the AI Next Time

The best way to avoid leaks in vibe coded apps is to ask for cleanup from the start. When the AI gives you code that adds a listener or starts a timer, ask:

"Does this code clean up after itself? Add the code to remove any listeners, clear any timers, and release any DOM references when they are no longer needed."

Most AI tools will add the cleanup if you ask. The problem is that most people do not ask. Speed is the goal. Cleanup feels like a detail. It is not. It is the difference between an app that runs well for a week and one that crashes on Monday morning.

Quick Checklist

Before you ship, go through this list for every feature that has side effects:

• Did I add an event listener? Did I remove it when done?
• Did I start a timer? Did I save the ID and clear it when done?
• Did I remove a DOM node? Did I set the variable to null?
• Do I have a global array or object? Does it have a size limit?
• Does anything keep running in the background when the user is not using that part of the app?

If you can answer yes to the cleanup question for each one, your app will not leak. It is not complicated. It just needs to be checked.

Summary

Vibe coding is fast and it works. But the AI writes for the happy path. Memory cleanup is not the happy path, so it often gets skipped. Use the browser Memory tab to confirm a leak. Use the heap snapshot and allocation timeline to find where it comes from. Fix the three most common causes: event listeners, timers, and detached DOM nodes. Cap your global data. And ask the AI to include cleanup from the start.

Your users will never know you fixed it. That is how it should be.

Written for developers who ship fast and want their apps to stay fast.