Chain puller is a chain tool which has two functions, one is to bring both open ends of the chain together for assembling or disassembling. They work by pressing a chain pin out to disconnect a chain, and if required, driving in a new connecting pin to put it back together. The second depending on the type of chain puller, some can used to help take tension off of the chain while breaking it.

When disassembling the roller chain, the chain puller has two positions where a chain can be inserted perpendicular to the puller, one close to the movable screw portion, the other lower down just above the fixed end. In each position, there are a pair of protruding tabs; one fits into the center of one link of the chain, the other fits into the center of the next link. With the chain properly in place, the pin is held in the center of the puller, so that the tip of the movable screw can press on the end of the pin. The end of the screw is slightly narrower than the pin, so that it can press the pin through the link.

 Most chain puller are designed for chains where the links have flat plates, which made up of a series of inner and outer plates, each held together with metal pins that are surrounded by a roller. For chains with complicated shaped plates designed to facilitate smooth shifting, specific chain pullers are available which are identical in design and operation, but have the ears protruding into the chain shaped in cross section to fit the links of the particular chain in question precisely, so as to hold the pin in the all-important vertical alignment with the screw of the tool.