Free Memory Test - Browser RAM / Heap Monitor

Memory Test

Measures browser heap usage live via performance.memory on Chrome and Edge, and lets you allocate typed arrays in configurable 10 MB chunks to watch the heap grow toward its limit. On Firefox and Safari (which do not expose performance.memory), the tool falls back to allocation-count only. Safely aborts before OOM. Browser-based, no install.

Live heap stats

—Used heap (MB)

—Total heap (MB)

—Heap limit (MB)

0Allocated by test (MB)

—Used / limit (%)

Stress allocation

Chunk size (MB)

Interval (ms)

Safety: allocation auto-stops if used heap exceeds 85% of the browser's heap limit, or after 500 chunks, whichever comes first. On Firefox/Safari (no performance.memory), the test stops at 300 MB self-allocated as a safety cap.

Heap growth graph

Green line: used heap. Yellow: total heap. Red dashed: browser heap limit. Chart updates every 500 ms.

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Memory Test guide

How to use the Memory Test accurately

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).

01 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...

02 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.

03 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.

04 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.

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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.

Memory Test FAQ

Common memory test questions

Why is "heap limit" different from my system RAM?

The heap limit is per-browser-tab, not per-system. Chrome desktop typically caps tabs at 4 GB regardless of whether you have 16 GB or 128 GB of system RAM, to prevent one tab from consuming the entire machine. Mobile browsers cap much lower (256-512 MB).

Is this a replacement for MemTest86?

No. This tool measures browser heap behavior, not hardware RAM stability. No JavaScript can access memory directly or test DIMM integrity. For real RAM testing (bad modules, XMP stability, overclock validation) use MemTest86 as a bootable USB, which runs outside any OS.

Why doesn't Firefox / Safari show heap stats?

performance.memory is a non-standard Chrome API. Firefox and Safari do not expose it to protect against memory-based fingerprinting. The tool falls back to tracking only what it has allocated itself, capped at 300 MB as a safety.

What does "Release & GC" actually do?

It drops all references to the allocated chunks, making them eligible for garbage collection. The browser's GC runs on its own schedule, usually within a few seconds. You should see Used heap drop without doing anything else.

Checklist

Utility checks to confirm

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)...
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...
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...