L39 Pilot reported the loss of brakes on landing resulted in a runway excursion.

Narrative

I was Pilot in Command of an Albatross L-39. I departed ZZZ at XA:20 in VFR weather on a proficiency flight over and to the west of the Valley; with the intention of returning back to ZZZ.When I returned for landing at XB:30; winds were reported calm and traffic was landing on Runway XX. I contacted the tower; entered the downwind and executed a normal VFR pattern and approach without incident.After touching down on Runway XX; I experienced no braking authority on main brakes. I pushed the control stick full forward; to ensure the weight-on-wheels switch was made; and again experienced no braking authority. I then pulled my emergency brakes lever aft and experienced no braking authority. Finally; I returned to pumping main brakes but again; was unable to discern any improvement in my rate of deceleration.Based on the AFM; landing weight and the atmospheric conditions at the time of landing; I should have required 1;729 ft. of ground roll to bring the airplane to a stop. I believe I had approximately 3;600 ft. of runway remaining at the point of touchdown.I believe I exited Runway XX at a speed of under 30 kts.; and rolled approximately 250 ft. into the grass before coming to a complete stop.There was no damage whatsoever to the airplane; or to the airport facilities.There were no injuries.