In cases of emergency, such as out-of-hospital cardiac arrests, the first few minutes are crucial for victims to receive care and have a positive outcome. However, emergency services often arrive on scene after those first few minutes, making any bridging solutions key. Finding a defibrillator or accessing a trained volunteer responder are some of the technological solutions that are being developed to support the chain of survival. This paper looks at technologies, in particular those linked to mobile apps that have been used to locate defibrillators and responder apps that enable responders to attend to nearby emergencies. We review a selection of apps and also assess the challenges and considerations for such apps.