Inclusion Criteria:  Diagnosis of major depressive disorder (MDD) per DSM-5 criteria Hamilton Rating Scale (17-item version)-HDRS score ≥ 17 at baseline Years of education ≥ 8 Having access to a smartphone with internet access at home Treatment refractoriness ≤ 3 antidepressants, at optimal doses and for appropriate duration No contraindications for tDCS (i.e., metallic plates on the head, brain devices, cochlear implants, cardiac pacemakers) No suicidal ideation with planning, or attempted suicide, in the 4 weeks prior to baseline  Exclusion Criteria:  Other psychiatric diagnoses (i.e., schizophrenia, schizoaffective disorder, bipolar disorder, obsessive compulsive disorder, attention-deficit and hyperactivity disorder, personality disorders, substance dependence and/or abuse disorders). Obs.: Anxiety disorders, as a comorbidity, will not be an exclusion criterium. Suspected or confirmed pregnancy Lactation Severe clinical or neurological conditions, including Post-Acute Sequelae of COVID-19 Depressive symptoms better explained by other clinical conditions (i.e., hypothyroidism, anemia) or other psychiatric disorders. Use of benzodiazepines > 10mg diazepam or diazepam-equivalent per day