Select Options > Keyboard/Mouse. Enable Allow Developers Console. Press '~' to activate the console. 

tongue_range <#> - (Default 750) Sets the maximum range of the smoker's tongue attack
z_pounce_damage X - amount of damage you want to do to survivors
z_witch_burn_time - Amount of time before a burning Witch dies from fire (does not effect caused by fire)
z_health - Change zombie health
z_speed - Change Zombie speed
director_no_human_zombies 0/1 - Disables/enables controllable Boss Infected on any map
director_panic_forever 0/1 - Enables/Disables never ending panics
director_force_panic - Forces a panic event
give ammo - Full Ammunition
give pistol - Get pistol
impulse 101 - Give Ammo to your primary weapon
give autoshotgun - Give auto shotgun
give first_aid_kit - give first aid kit
give health - give full health
give gascan - give gascan
give hunting_rifle - give hunting rifle
give molotov - give molotov
give oxygentank - give oxygentank
give_pain_pills - give pain pills
give pipe_bomb - give pipe bomb
give propanetank - give propanetank
give rifle - give you an MK 47 ( machine gun )
z_spawn weapon_SMG - give you the SMG
god - invincibility
buddha 1 - just like god but you receive damage (sometimes if you are the only survivor left, you can't receive damage from infected
sb_openfire or open_fire (console will tell) - makes your bot teammates shoot nonstop
director_no_mobs <1/0> - No mob rushes
firstperson - Play in first person (default), this cheat only necessary if thirdperson mode is enabled
Ent_Remove - Removes all bots
z_witch_damage <#> - Sets the amount of damage a Witch's attack does
thirdperson_mayamode - sets the camera to be fixed in place whle in either third person or third person shoulder mode. Enter once to turn on and enter again to turn off
thirdperson - sets the camera to be in third person mode
thirdpersonshoulder - sets the camera to over the shoulder third person mode
z_common_limit - sets the maximum amount of regular zombies
z_tank_health <#> - sets the maximum health of the tank
z_frustration_lifetime <#> - sets the number of seconds until the player loses control of the tank from not attacking survivors
sb_friendlyfire <1/0> - sets whether or not bots (and only bots) are allowed to do friendly fire damage
director_stop - Shuts off all wanderers, mobs, specials, and bosses
z_spawn zombie - spawn 1 zombie
boom - spawn a active pipebomb under you
z_spawn - spawn a special infected
z_spawn mob - spawn a zombie horde
z_spawn boomer - spawn boomer at location of crosshair
z_spawn hunter - spawn hunter at location of crosshair
z_spawn smoker - spawn smoker at location of crosshair
z_spawn tank - spawn tank at location of crosshair
noclip - Toggles no clipping mode
z_witch_allow_change_victim <1/0> - True/false setting that allows the witch to change targets instead or focus on the one survivor that alerted her first
sv_infinite_ammo 1 - unlimited ammunition 

At the main menu, select "Options," then "Keyboard/Mouse." Enable "Allow Developers Console." During gameplay, press "~" to access the console. Type in "Sv_Cheats 1" and press "Enter" to enable the cheats. Then, enter any one of the following:

Ent_Remove	Removes All Bots
sv_infinite_ammo 1	Unlimited Ammunition
give pistol	Get Pistol
god	Invincibility
noclip	Toggles No Clipping Mode
give ammo	Full Ammunition
z_spawn weapon_SMG	Gives you the SMG.
Vocalize	Vocalizes/makes the player say anything like vocalize playereatpills
z_spawn mob	spawns a zombie horde
z_spawn <bossname>	spawns a special infected (infected names:hunter,boomer,smoker,witch,tank)
give hunting_rifle	gives hunting rifle
z_spawn tank	Spawns tank at location of crosshair
z_spawn smoker	Spawns smoker at location of crosshair
z_spawn hunter	Spawns hunter at location of crosshair
z_spawn boomer	Spawns boomer at location of crosshair
give health	gives full health
give autoshotgun	Gives auto shotgun
give pain_pills	Gives pain pills
firstperson	Play in first person (default); this cheat is only necessary if thirdperson mode is enabled
give rifle	Gives you an Mk 47 (machine gun)
thirdperson	Sets the camera to be in third person mode.
thirdperson_mayamode	Sets the camera to be fixed in place while in either third person or third person shoulder mode. Enter once to turn on and enter again to turn off.
z_health	Change Zombie Health
z_common_limit	Sets the maximum amount of regular zombies
director_panic_forever 0/1	Enables/Disables never ending panics.
director_force_panic	Forces a panic event
z_speed	Change Zombie Speed
z_spawn zombie	Spawns 1 Zombie
give pipe_bomb	gives pipebomb
give propanetank	gives propanetank
give oxygentank	gives oxygen tank
give molotov	gives molotov
give gascan	gives gascan
give first_aid_kit	gives you first aid kit
fire	Spawns a lighted molotov right on the floor under you.
boom	Spawns a active pipebomb under you.
z_frustration_lifetime <#>	Sets the number of seconds until the player loses control of the Tank from not attacking survivors
sb_friendlyfire <1/0>	Sets whether or not bots (and only bots) are allowed to do firendly fire damage
thirdpersonshoulder	Sets the camera to over-the-shoulder third person mode
tongue_range <#>	(Default 750) Sets the maximum range of the smoker's tongue attack
director_stop	Shuts off all wanderers, mobs, specials, and bosses
director_no_mobs <1/0>	No mob rushes
z_tank_health <#>	Sets the maximum health of the Tank
z_witch_allow_change_victim <1/0>	True/False setting that allows the witch to change targets instead or focus on the one survivor that alerted her first
z_witch_burn_time	Amount of time before a burning Witch dies from fire (does not affect damage caused by fire)
z_witch_damage <#>	Sets the amount of damage a Witch's attack does.
director_no_human_zombies 0/1	Disables/enables controllable Boss Infected on any map
retry	You can unlock achievements while using cheats (after entering sv_cheats 1, enter retry so that it will restart the game with the cheats on)
impulse 101	Gives Ammo To Your Primary Weapon
buddha 1	just like god but you receive damage(sometimes if you are the only survivor left you can't receive damage from infected)
z_pounce_damage X	amount of damage you want to do to survivors
sb_give XXXX	x= desired entity to give to your bot teammates (the console should give you a list)
tongue_fly_speed X	x= amount of speed that you want for the smoker's tongue to fly
z_pounce_door_damage X	x= desired amount of damage to pounce through doors
sb_openfire or open_fire (console will tell)	makes your bot teammates shoot nonstop
ent_fire !self addoutput "gravity 0.10	Enables low gravity jumps, falls, and pounces. (works for infected players)