MegaMod

MegaMod is a clientside mod created by the owner of Beyta, cutezyash. It is designed specifically for Beta 1.7.3, and introduces plenty of quality of life features to bring the game up to the standards of modern Minecraft. MegaMod achieves things without altering gameplay, such as the new up-to-date main menu design, sprinting, custom server packets, new GUIs, virtually complete mod compatibility and much, much more. It also features many tools to enhance your singleplayer experience, including commands and flying.

Installation Guide: https://www.oldhaven.net/megamod.html