Abstract Background Drug checking uses chemical analytical technologies to analyze drugs from the unregulated market to reduce substance use-related risks. We aim to examine the frequency of third party use of a community drug checking service to explore the potential for harm reduction to extend beyond the individual into the community, increase service accessibility, and to contribute to upstream interventions in the supply. Methods Over 31 months, data were collected from a point-of-care drug checking service operated in Victoria, Canada. Through the implementation of survey questions at the intake of the service, data were collected about whether the drug check was for the individual, to sell, and/or for others. Results Just over half (52%) of service users were checking for reasons that extended beyond individual use. When checking for others, friends were the most common response, representing 52% of responses, and outreach/support workers checking for others was the second most at 32%. Twelve percent of service users reported checking to sell or for a supplier. Conclusions Third party checking is a frequent, and important aspect of drug checking services, which through facilitating community engagement and increasing accessibility, has expanded the reach of interventions beyond individuals to reduce risks within the unregulated market. Therefore, drug checking as an overdose response should be responsive and accessible for those using the service on the behalf of others.