This thread is dedicated to implementing simple rules to end the divide.

I will start with three general rules and some changes for the fighter and the monk.

• Fighter, Monk, Rogue and Barbarian:
• Get a feat every even class level.
• Get extra attack at levels 5, 9, 13 and 17.
• Melee attack penalty:
• Can give penalty to attacks of magnitude smaller or equal to class level.
• Double the magnitude of the penalty and add it to damage.
• Has to choose the penalty before the roll.
• Fighter:
• Also get feats at levels 3, 7 and 15.
• Also feats extra attack at levels 11 and 20.
• Monk:
• Amount of ki points equals class level plus 4.

General homebrews explanation:

• Spells give casters infinite versatility. What casters have via spells, martial could have via feats. It would make them stronger, more customizable and have more options. 
• I think it is really interesting how casters keep gaining more slots and higher levels of spells, but martials only improve their damage at level 5 and then never again. It should be a continuous improvement.
• The melee attack penalty would make melee martials, hands down, the best at single-target damage (what they should've been from the start). Also, it takes away the necessity of Great Weapon Master (buffing sword & board, the monk, and the rogue), and it justifies melee over ranged martial.
• I would say the best thing about those buffs is that they really only become powerful past level 5, where the martial-caster divide usually occurs. Hopefully, at least, they can ****** the total divide to around the 17th level instead of around the 13th.
• Another very good thing is that they are extremely simple to implement.

Fighter homebrew explanation:

• The fighter is the class that gains more feats and more attacks. Naturally, now that every other martial gains more feats and attacks, he would have to gain even more extra stuff.

Monk homebrew explanation:

• Even with all of the buffs, Monks are still weaker than other martials. Having 6 Ki points at level two is very great, considering the average encounter has around 4-5 rounds. At the 5th level, having 9 Ki points, the Monk can have his good features at any time, even face two encounters in a roll without needing a short rest.

It actually makes things more balanced, good job on this point. I adopt this system without any hesitation !