We provide an overview of optical coherence tomography (OCT) applied in the field of non-destructive testing (NDT). The applications include examples for structural polymer material testing at mesoscopic size scale, visualizing and validating internal sub-surface micro-defects, or characterizing the coating and bonding quality in multilayer samples. Furthermore, dynamical processes observed by OCT in their temporal progress can be demonstrated in the context of NDT as well as multimodal settings for gaining structural and specific insights on the materials tested. We will also regard the challenges for performing dimensional measurements and optical metrology by OCT imaging. In addition, novel developments and trends at illumination and detection sites will be discussed as essential components and requirements for the progress in OCT technology. This includes newly accessible spectral ranges under the view point of sensing as well as adaptable learning tools under the view point of data and image processing, which will round off the topic.