Acknowledgement Protecting the data of human rights defenders (HRDs) is critical due to the sensitive nature of their work and the high risks they face, including surveillance, harassment, and physical harm. The APF Secretariat prepares these guidelines for its members to strengthen their complaint handling, monitoring and reporting system capabilities to consider digital security threats, particularly on HRDs. Protecting the privacy and the identity of HRDs, their families, and communities is of the utmost importance. HRDs need to feel confident and assured when making a complaint about a human rights violation to their NHRIs for an investigation. This practical guide is developed under the European Union NHRI Phase 3 Project. The APF Secretariat express gratitude to Fia Hamid-Walker, Human Rights Defenders Project Officer, for her leadership and dedication to this initiative. We are extremely thankful to the elevenM consulting team for creating and compiling this guide, as their expertise and support have significantly enhanced this work. 4 Data Protection Guidelines for NHRIs Toolkit