The report lifts the curtain on the Brazilian data workers involved in global AI production chains. They do 'micro-tasks' to generate and annotate data for machine learning, while also checking algorithmic outputs and occasionally, taking the place of failing automation. They use international digital labor platforms through which they execute on-demand tasks, mostly for AI producers located in the Global North. As platform workers, they are paid by piecework and have no long-term commitment to the buyers of their outputs. Some highlights: - Three out of five Brazilian data workers are women, while in most other previously-surveyed countries, women are a minority (one in three or less). - 9 reais (1.73 euros) per hour is the average amount earned on platforms. - There are at least 54 micro-working platforms operating in Brazil. - One third of Brazilian data workers have no other source of income, and depend on microworking platforms for subsistence. - Two out of five Brazilian data workers are (apart from this activity) unemployed, without professional activity, or in informality. In Brazil, platform microwork arises out of widespread unemployment and informalization of work. - Three out of five of data workers have completed undergraduate education, although they mostly do repetitive and unchallenging online data tasks, suggesting some form of skill mismatch. - The worst microtasks involve moderation of violent and pornographic contents on social media, as well as data training in tasks that workers may find uncomfortable or weird, such as taking pictures of dog poop in domestic environments to train data for "vacuuming robots". - Workers' main grievances are linked to uncertainty, lack of transparency, job insecurity, fatigue and lack of social interaction on platforms.