Hybrid pixel array detectors (HPADs) have a major impact on the science performed at x-ray synchrotron radiation sources. Broadly speaking, HPADs are of either the photon-counting or integrating variety. The success of photoncounting HPADs at storage rings is well described in the contribution by Brönnimann and Trüb. However, for experiments at x-ray free-electron laser (XFEL) sources, as well as for many fast time-resolved measurements at storage ring sources, photon counting is not an option because too many x-ray photons arrive too quickly for counting electronics to keep up with the local count rate. In these cases, fast analog-integrating systems are mandatory. By using innovative and adaptive front ends, one can achieve both a high dynamic range and a noise sufficiently low for reliable single photon detection. For frame rates above a few tens of kilohertz, temporary in-ASIC frame storage is mandatory. This can be done either in digital or in analog form, each having advantages and disadvantages. HPADs also need to be designed to cope with x-ray damage from extremely high radiation doses provided by current and next-generation x-ray sources. All these developments are summarized, along with some representative groundbreaking experiments performed with integrating HPADs. © Springer International Publishing Switzerland 2016.