How The Memory Test Works
On Chrome and Edge, the test reads the non-standard performance.memory API every 500 ms to pull three values: usedJSHeapSize (how much the current page is holding), totalJSHeapSize (how much the browser has reserved for this tab), and jsHeapSizeLimit (the hard ceiling the browser will enforce before terminating the tab). The allocator creates fresh Uint8Array typed arrays of the chosen chunk size and retains them in a local array so they cannot be garbage-collected. Writing one byte per 4 KB page guarantees the allocation is actually committed to memory rather than lazy-allocated. Firefox and Safari do not expose performance.memory, so the tool falls back to tracking only its own allocation total and caps the run at 300 MB.
What "Heap Limit" Actually Is
The heap limit is the browser's decision, not the operating system's. On 64-bit Chrome desktop the default is roughly 4 GB for the main thread's isolate, though this varies by build and memory pressure. On Chrome for Android the limit is much lower — typically 256-512 MB — because mobile devices prioritize killing tabs over letting one tab consume the entire system. The limit also differs between the main thread and Web Worker threads, and between regular tabs and Service Workers. This tool always reports the main thread's limit, which is the one that matters for the page you're looking at.
For laptop buyers, browser memory limits are only one part of the story. If your work also depends on GPU VRAM for games, AI tools, or creative apps, use our best laptops with good GPU guide alongside this memory test.
Detecting Memory Leaks In Web Apps
One of the genuinely useful uses of this page is leak detection. Load the app you suspect is leaking in a separate tab, come back here, and click Release & GC to baseline this tab at low usage. Then keep watching the Used heap while you exercise the suspect app (navigate between pages, open/close modals, do whatever action you think triggers the leak). If Used heap on the suspect tab keeps climbing and never drops after interaction, there is likely a detached DOM or lingering event-listener chain keeping allocations alive. The real leak hunt happens in Chrome DevTools Memory panel (heap snapshots), but this page is a quick "is there a problem here?" check.
This Is Not A Hardware RAM Stability Test
No JavaScript running in a browser tab can test RAM at the hardware level. The browser handles all allocation through an allocator and garbage collector, with explicit limits and page-level virtual-memory isolation. For real RAM stability testing — detecting bad DIMMs, validating an XMP profile, or verifying a DDR5 kit is stable — use a bootable tool that runs outside any OS: MemTest86, MemTest86+, or HCI MemTest when you need to test within Windows. Our browser-based test is useful for web-app heap diagnostics and browser-limit curiosity, not for answering "is my RAM dying?".
