FrostsimThe browser engine
SimulationCraft in your browser
Frostsim compiles SimulationCraft to WebAssembly so you can simulate a retail WoW character on your own device. You do not need to install the SimulationCraft desktop application to run a browser sim.
What happens when you run a sim?
Frostsim turns your imported character and settings into SimulationCraft input. A browser worker runs the engine, and Frostsim displays the resulting report. Browser mode uses your device's CPU and memory; a larger gear search usually takes more work than one Quick Sim.
The engine is downloaded separately from the app and cached for reuse. A first visit or a new engine revision can require a download before the run begins. Download size and speed depend on the published engine and your connection.
Browser requirements
Use a current browser with JavaScript and WebAssembly enabled. Where the browser supports shared memory and the site supplies the required isolation headers, the engine can use multiple threads. A single-thread fallback is available for environments without shared memory, with fewer comparison capabilities.
Open Help to see what this browser supports, the loaded engine, and offline cache status. Keep the tab open while a run is active. Available memory and device speed limit how much work you can do locally.
Supported WoW versions: Live and PTR
Frostsim targets retail World of Warcraft. Live is the default channel. PTR uses a separately published engine with test-realm data when a compatible pack is available; choosing PTR cannot turn a Live engine into a test-realm engine.
Check the game version and SimulationCraft revision in Help and in your reports. Support for a new patch depends on the published engine and matching game data. These guides do not promise Classic or every historical expansion.
What stays on your device?
Anonymous browser simulations run locally, and local characters and reports are stored in this browser. An Armory lookup sends the region, realm, and character name to retrieve public character data.
Frostsim Cloud is optional paid compute. With an eligible subscription, a run may use cloud workers; choose This browser when you want local execution. Cloud runs send simulation input to those workers. Cloud character saves, hosted report links, and requested AI explanations also use online services. Every paid tier includes no ads while you are signed in.
Start with one character
Follow the character simulation guide, run a baseline in Quick Sim, then use the appropriate comparison tool for your next decision.