A seam ripper is a specialty notion that features a curved blade ending in a sharp point on one side and and a small ball on the opposite edge, to help protect against damaging adjacent fabric. Seam rippers are available in sizes to fit different hands, ranging from 2¾ inches to 6 inches (7–12.7 cm). They also come in a variety of colors and handle styles.

There are other design variations for the seam ripper. Some have a lid to cover the blade, while others fold or slide in and out of a case, like a pocketknife or a retractable knife. Some seam rippers are designed with a magnifier attached to help bring the work area into better view, while other models sport a flashlight to assist vision.

A typical seam ripper has no moving parts, and the cutting motion is made by the hand movements of the operator, but there are also spring action seam rippers. Another model features a handle with two attachable heads –- a seam ripper and a threader –- to be used as needed. Still other seam rippers include a handle and specialized blades for the two tasks of seam ripping and buttonhole cutting.

As its name indicates, a seam ripper is a handy tool to cut regular and serged seams open, but it can do much more than that. A seam ripper is the tool of choice for a number of tasks, including taking out basting; unpicking stitches that are too big, too small, or in the wrong place; and removing tailor's tacks. Other tasks for which they are suited are cutting off buttons and removing snaps.

People don’t always consider using a seam ripper when they need to prepare the slit for a hand-worked buttonhole or create the slit after a machine-worked buttonhole is stitched, but this is another task that the seam ripper excels at. Last but not least, embroiderers use seam rippers, among other tools, to cut away excess fabric when doing cutwork embroidery.