This extension requires that OPUS-CAT MT Engine running on the local computer. The extension extracts the source text from the currently active Memsource segment and sends it to OPUS-CAT MT Engine for translation. The translation is then displayed in the OPUS-CAT MT Engine overlay (part of the OPUS-CAT MT Engine), which can be displayed simultaneously with the Memsource browser UI. The translation can be copied to Memsource by pressing a dedicated hotkey.