Background: In the UK, sexual health services are shifting online. Uptake of online partner notification and management (OPNM) is low and there is a lack of evidence to guide its development and deployment. This study explored the acceptability of, and barriers and facilitators to, OPNM to inform the optimisation of an eSexual Health Clinic (eSHC). Methods: We conducted semi-structured qualitative interviews (n=25) with sexual health service users recruited from clinics and the community in the UK (10/2021-01/2023). Participants were >/=16 years and a recent contact of/diagnosed with a bacterial STI. Interviews explored experiences of PN, barriers to and facilitators of OPNM, and involved a walkthrough of an OPNM prototype pathway (Figure 1) using a range of fictional personas/scenarios. We analysed transcripts using thematic analysis. Results: Participants were diverse, particularly in terms of gender, sexuality, and disability status. Most found OPNM acceptable and described using some online PN methods themselves (e.g., texting). Participants wanted an online system to be tailored to the nature of their relationships, their communication/language use preferences, and degree to which they wanted to be identifiable/anonymous. An integrated pathway (e.g., an eSHC) for receiving results, accessing treatment, and linking partners to appropriate online management was important to many participants, who expressed strong personal responsibility for providing something 'actionable' (e.g., clickable link for partners to access testing/treatment) when doing PN. Some were reluctant to share personal data with an OPNM system or to click on a link shared with them. Where participants preferred to talk to partners offline, they wanted to access PN support resources within the online pathway. Conclusion: In this study, OPNM, integrated into an eSHC, was highly acceptable. Important elements to address in design and implementation are personalisation according to user preferences and needs, online support for offline PN where preferable, and consideration of trust, privacy and security issues from index patient and partner perspectives. Online systems which enable partner management as well as simply notifying partners could increase the appeal of online PN, generating buy-in from users and facilitating increased testing/treatment of contacts and improved surveillance. [ABSTRACT FROM AUTHOR]