StepUp Mod (184.108.40.206) allows you to climb one block without needing to jump. This mod can be deactivated if your character is unable to walk up blocks on a server that has it activated. You could also get banned from the server for “hacking”. To activate or deactivate the effects, press “J”. You can change the keybind in the controls menu.
This mod allows you to cycle through three auto jump options by using the StepUp keybind.