ðə ɹᵻlˈiːs ʌv fˈaɪɚfɑːks fˈɪfti sˈɛvən kwˈɔntəm mˈɑːɹkt ðə swˈɪtʃoʊvɚ fɹʌm ˌɛksjˌuːˈɛlbˈeɪst ˈæd ˈɔnz—wˌɪtʃ ɐlˈaʊ ɛkstˈɛnʃənz tə mˌeɪk ˈɑːɹbɪtɹˌɛɹi tʃˈeɪndʒᵻz tə fˈaɪɚfɑːks kˈoʊd—tə ðə wˈɛb ɛkstˈɛnʃənz ˌeɪpˌiːˈaɪ, wˌɪtʃ stɹˈɪktli lˈɪmɪts hˌaʊ mˈʌtʃ kəntɹˈoʊl ɛkstˈɛnʃənz hæv ˌoʊvɚ ðə bɹˈaʊzɚ ænd ˈɪntɚfˌeɪs.
The release of Firefox 57 Quantum marked the switchover from XUL-based AddOns—which allow extensions to make arbitrary changes to Firefox code—to the WebExtensions API, which strictly limits how much control extensions have over the browser and interface.