A chip on film, including a base material provided with at least one row of output pads, wherein along an arranging direction of the output pads, an area where each row of output pads is located includes a first region, a second region and a third region, the second region is in the middle of the area where the row of output pads is located; the shape of each output pad located in the second region is different from the shape of each output pad located in the first region and the third region, and a maximum length spanned by each output pad located in the second region in the arranging direction is smaller than a minimum value among maximum lengths spanned by each output pad located in the first region and the third region in the arranging direction. A flexible display panel and a display device are further disclosed.