@biancotitanio it's not "mass unmuting", but maybe you don't know that from the web frontend you can click on the "..." button next to your profile picture and choose "muted accounts", then you have a complete list with each muted account and an "unmute" button next to it; otherwise, for proper "mass unmuting", you may write a script using this API endpoint, https://docs.joinmastodon.org/methods/mutes/, it's all written there (you would use https://pagan.plus/api/v1/mutes, you can get the token you have to send as "Header: Authorization Bearer <token>" from the web frontend, at Preferences -> Development -> New application), but if the accounts you have to unmute are more than 300 you should also take into account the rate limits, https://docs.joinmastodon.org/api/rate-limits/