# Stack & Heap Simulator > Interactive memory simulator: visualise stack frames, heap blocks, and pointers side-by-side. Watch allocation, deallocation, dangling pointers, memory leaks, and heap fragmentation in real time. Five guided scenarios. All client-side. β€’ No tracking. Canonical page: [https://chrome-stats.com/d/stack\_heap\_simulator](https://chrome-stats.com/d/stack_heap_simulator) ## Overview - **ID:** `stack_heap_simulator` - **Platform:** Firefox - **Type:** Firefox add-on - **Status:** Available - **Publisher:** Libor Benes (Dr. B) - **Category:** web-development,privacy-security,search-tools - **Daily users:** 2 - **Version:** 1.0 - **Last updated:** 2026-05-13 - **First published:** 2026-05-10 - **Size:** 34 KB - **Data as of:** 2026-09-10 - **Store listing:** [Firefox Add-ons Store](https://addons.mozilla.org/firefox/addon/stack_heap_simulator/) - **Website:** [https://www.linkedin.com/in/LiborBenes](https://www.linkedin.com/in/LiborBenes) ## Description 🧠 Stack & Heap Simulator brings one of computer science's most important concepts directly into your Firefox sidebar β€” an interactive, colour-coded visualisation of how programs use memory, updated live as you click. πŸ” WHAT IT DOES: A persistent Firefox sidebar lets you build up a real memory picture step by step: push function call frames onto the stack, allocate blocks on the heap, connect them with pointer variables, then free blocks and pop frames β€” and watch exactly what goes wrong when you don't do it in the right order. πŸ“ TWO-COLUMN CANVAS: 🟒 Left column β€” the Stack. Grows downward (high β†’ low addresses). Each function call adds a named frame containing local variables and a return address. The active frame glows purple; the SP (stack pointer) is marked with a dashed line. πŸ”΅ Right column β€” the Heap. Grows upward (low β†’ high addresses). Each malloc() adds a blue block with its ID, size, and address. New blocks appear above older ones, correctly reflecting heap growth direction. 🟑 Yellow BΓ©zier arrows connect stack pointer variables to their heap blocks across the gap between columns. πŸ”΄ MEMORY ERRORS β€” MADE VISIBLE: Unlike reading about memory bugs in a book, this simulator shows them in colour: β€’ Dangling pointer β€” free a heap block while a pointer still references it. The arrow and variable turn red immediately, labelled DANGLING. β€’ Memory leak β€” pop a stack frame without freeing its heap blocks. Orphaned blocks turn orange, labelled LEAKED. β€’ Heap fragmentation β€” allocate several blocks, free alternating ones, and see the live (blue) and free (gray dashed) blocks interleaved in the heap column. πŸ“– FIVE GUIDED SCENARIOS: Click any scenario card in the Scenarios tab to watch an auto-play walkthrough at 650 ms per step: β€’ Basic Allocation β€” the fundamental stack-to-heap relationship with a pointer. β€’ Function Call Stack β€” push main() β†’ foo() β†’ bar() with local variables, then pop them LIFO. β€’ Memory Leak β€” return from a function without freeing heap memory. β€’ Dangling Pointer β€” free a block while a stack pointer still holds its address. β€’ Heap Fragmentation β€” allocate four blocks, free the alternating ones, see the gaps. πŸ“š BUILT-IN REFERENCE (Explain tab): Four compact concept rows β€” Stack, Heap, Pointers, and Call Frames β€” give the essential theory in a format that fits entirely on screen without scrolling, followed by a memory layout diagram showing high-address stack base, stack growth direction, free space, heap growth direction, and low-address heap base. πŸ”’ SECURITY-FIRST ARCHITECTURE: βœ… No data collection β€” explicitly declared in manifest.json via data_collection_permissions: ["none"]. βœ… No telemetry β€” no analytics, no external pings, zero network requests of any kind. βœ… No eval() β€” safe, audited code meeting Firefox extension standards. βœ… No innerHTML β€” all rendering via the Canvas 2D API; all DOM updates via textContent. βœ… No permissions β€” the permissions array in manifest.json is completely empty. βœ… Input validation on every state mutation before it touches the canvas. βœ… Content Security Policy locked to script-src 'self'. 🎯 PERFECT FOR: β€’ Students in systems programming, OS, or C/C++ courses who want a visual complement to lectures. β€’ Developers debugging memory errors or learning allocator behavior. β€’ CS educators who want an interactive demo to show alongside a whiteboard. β€’ Anyone who has ever wondered what malloc(), free(), stack frames, and pointers actually look like at runtime. βš™οΈ TECHNICAL: β€’ Firefox 140.0+ desktop only Β· Manifest v2 Β· Sidebar panel. β€’ Zero network requests Β· Zero storage Β· No background scripts Β· No account required. β€’ Runtime Execution RAM Footprint: ~42 KB (core scripts: manifest.json + panel.html + styles.css + script.js). β€’ Total Extension Download/Install Size: ~ 96KB (including README.md). β€’ No permissions required β€” manifest.json permissions array is empty. πŸ”’ 100% Client-Side Β· No Data Collection Β· No Tracking Β· No Account. 🧠 Stack & Heap Simulator: See the memory. Understand the machine. ## Rankings - #67,544 β€” Overall - #77 β€” fragment ## Safety - **Risk impact:** Very low risk impact - **Risk likelihood:** High risk likelihood ### Analysis details - This permission has no access or impact on the user's system or data, thus carrying no risk. - This extension website URL may be invalid > Some risk analysis details are omitted from this free response. 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