Mercuriall Audio Software is a Russian audio software developer founded in 2015 by programmer Vladimir Titov and mix engineer Vjacheslav Tikhonov. The company specializes in guitar amplifier and effects simulation plugins for VST, AU, and AAX hosts, using a combination of state-space circuit simulation and neural-network approximation (marketed as the Mercuriall Neural Hybrid Engine) to model analog hardware in real time.

The company's catalog centers on Ampbox, a modular plugin platform that hosts individually modeled amps, pedals, and cabinet processing. Notable titles include Spark (modeled on Marshall-style amps), U530 (based on the Engl E530 preamp), SS-11X, ReAxis, Rectofire, Euphoria, BST-7, SUN-100, and the 6160III, alongside Tweed Blues and Tweed Bass amp emulations and the iPad-targeted Amp One. The product line also includes free effect pedal modules and cabinet IR loaders.

Mercuriall is generally associated with the high-gain and metal end of amp-sim software, where it competes with developers like Neural DSP and STL Tones, and is known among home and project-studio guitarists for plugins that aim to match the gain feel and harmonic response of the original tube circuits rather than relying on tone-matching or static waveshaping.

Mercuriall has 6 products cataloged on Equipboard, including Amp Simulator Plugins, Distortion Plugins, and Filter Plugins. Their gear is featured by 1 artist, with the strongest followings in Rock and Metal. Notable users include Sergey Golovin.