Abstract: A clampless coupling which attaches a hose to a nipple without need of a clamp at the end of the hose to ensure sealing, including a connector and a nipple of a fluid system component. The connector is sealingly pre-connected at one end with a hose; the opposite end is in the form of a sleeve. The sleeve features a notch at its forward end, a boss on a resilient lock arm, and an O-ring seal. The nipple has a pocket depressionally formed on its outside nipple surface and an alignment tab. In operation, a user slides the sleeve over the nipple by pressing the connector toward the near end of the nipple. As the sleeve slides over the nipple, the tab is received by the notch to align the connector with the nipple, the boss drops abuttably into the pocket, and the O-ring seal sealingly compresses between the nipple and the connector. A seal assurance feature reveals improper connection when a pressure test is undertaken.