Introduction - Since July 1, 2019, the "Au labo sans ordo" (ALSO) program has offered free, prescription-free HIV testing in all private medical laboratories in Paris and the Alpes-Maritimes department. This article describes the users of the ALSO program and compares their characteristics to those of individuals who undergo HIV testing in laboratories with a doctor’s prescription or at CeGIDDs. Methods - A cross-sectional study was conducted during the week of November 18–23, 2019, in 240 laboratories and 11 CeGIDDs across both departments. An anonymous self-administered questionnaire was offered by reception staff to adults undergoing an HIV test. Two logistic regression models were used to compare ALSO users with individuals who had (1) a prescribed test; (2) screening at a CeGIDD. Results - The analysis included 3,144 questionnaires (295 ALSO users, 2,138 individuals with a prescribed test, and 711 CeGIDD users). Compared to individuals with a prescribed test, ALSO attracted more heterosexual men (42% vs. 28%), who were well-integrated socially but relatively distant from healthcare (32% vs. 21% visited ≤1 time/year), and had multiple sexual partners (60% vs. 49%). The CeGIDDs reached a younger population (42% vs. 21% under 25) and one more exposed to HIV: 24% were MSM (vs. 15%), 79% had multiple sexual partners, and 53% (vs. 19%) had ≥1 indicator of exposure. Conclusion - The ALSO program, described by users as practical and accessible, attracts a population distinct from other services, notably more heterosexual men who are often less reached by screening initiatives.