Edgebug is a glitch in the engine that allows you to fall down a long distance without taking any damage and/or dying, by hitting the exact edge/brush of a certain block (in the case of Portal 2 and some of its mods, allows you to keep a button activated when there is nothing on it). Especially easy to do on stairs or other broad edges.



The engine applies the fall damage if the check if the player is on ground succeeds. Such checks are done at the end of movement frames. When you perform an edgebug, you start in mid-air and end in mid-air in one movement frame, while sliding off of an edge happens in-between. The game never knows if you were on the ground or not, never applying the fall damage.

It doesn't matter if you are ducked or not when doing an edgebug, both is going to work fine.



Attempting to perform an edgebug with a lower framerate increases the success rate of triggering the glitch.

It's not possible to perform an edgebug without any horizontal velocity.

When you perform an edgebug, all of your vertical velocity drops to 0, while horizontal velocity stays the same. In some cases this will make the edgebug a choice of landing method as you wouldn't have to make an additional jump as you would with Jumpbug.