Inclusion Criteria:  Male or female 18 - 65 years of age at the screening visit, fluent in English and able to read, comprehend, and willingly sign the informed consent form (ICF). Voluntarily seeking treatment for OUD. In the judgment of the Investigator has the appropriate hearing, vision, manual dexterity, ability to understand instructions, and ability to use and understand internet-based applications. Currently meets the criteria for moderate or severe opioid use disorder according to Diagnostic and Statistical Manual of Mental Disorders (DSM)-V (Appendix B). Has a positive UDS for opioids at screening that is consistent with their drug use history. In good health as determined by lack of clinically significant abnormalities in health assessments performed at screening. Agrees not to take any buprenorphine products other than those prescribed by the Investigator during participation in the study, and agrees to use OXD01 as directed if randomized to that treatment group. Completed SL BUP/NAL induction, with physical withdrawal symptoms reduced so the subject is able to fulling participate in OXD01 training, if randomized to that treatment group, and is no greater than 14 days from the first dose of SL BUP/NAL induction.  Exclusion Criteria:  1. Unwilling or unable to comply with the requirements of the protocol or are in a situation or condition that, in the opinion of an Investigator, may interfere with participation in the study (e.g., does not have reliable internet access).  2. History of allergy or sensitivity to naloxone, buprenorphine or other opioids, or history of any drug hypersensitivity or intolerance which, in the opinion of an Investigator, would compromise the safety of the subject.  3. Used an investigational drug within 30 days or 5 half-lives (whichever is greater) prior to randomization.  4. Received prescribed medication-assisted treatment with buprenorphine, methadone, or naltrexone for opioid use disorder within 14 days prior to screening.  5. Past or present diseases that, judged by an Investigator and based on available medical history/records, may jeopardize the safety of the subject or impact the validity of the study results.  6. Tongue piercing, or piercings in the mouth or oral deformities that may affect sublingual absorption, in the opinion of an Investigator.  7. Hospitalization for a psychiatric disorder in the past 30 days, not including inpatient treatment for drug rehabilitation.  8. Schizophrenia, or other serious mental illness defined as a mental, behavioral, or emotional disorder resulting in serious functional impairment which substantially interferes with or limits participation in the study.  9. A Quick Inventory of Depression Symptoms - Self-Report (QIDS-SR, Appendix C) score ≥ 16 (severe depression) or a rating of 2 or 3 for question 12 (Thoughts of Death or Suicide) at screening.  10. A current diagnosis, other than opioid use disorder, requiring chronic opioid treatment.  11. Chronic pain that is unremitting or unstable. 12. Current DSM-V diagnosis of moderate to severe substance use disorder for psychoactive substances other than opioids, caffeine, marijuana, or nicotine.  13. Requires current use of medications that are strong inhibitors or inducers of cytochrome P450 (CYP) 3A4 (Section 4.3.1).  14. Any pending legal action that could affect participation or compliance in the trial.  15. Is an employee of the Investigator or the trial site, with direct involvement in the proposed trial or other trials under the direction of the Investigator or trial site, or is a family member of the Investigator or an employee.