Starbucks Monkey forest is mostly quiet, but the co-working space at Beluna is also pretty good, Kabana at K Club Ubud. Those places are nice with unique amenities and comfy atmospheres. For example, in Kabana, they have a pool that we can enjoy while in the break between work, so it is really chill and at the same time a productive place to work from. While Beluna has a lovely rice fields view that can relax your mind on a day of hard work.
