MITCalc - Torsion Springs 

Geometric and strength designs of spiral cylindrical torsion springs loaded with static or cyclic loading. Application supports Imperial and Metric units, is based on ANSI, ISO, DIN standards and support many 2D and 3D CAD systems.
spring springs cylindrical spring torsion spring spiral spring en 13906-2 din 2088 dynamic strength check.

MITCalc - Tension Springs 

Geometric and strength designs of helical tension cylindrical springs loaded with static loading. Application supports Imperial and Metric units, is based on ANSI, ISO, DIN standards and support many 2D and 3D CAD systems.
spring springs cylindrical spring tension spring helical spring en 13906-2 din 2089-2 din 2097 dynamic strength check.

MITCalc - Compression Springs 

Geometric and strength designs of helical compression cylindrical springs loaded with static or fatigue loading. Application supports Imperial and Metric units, is based on ANSI, ISO, DIN standards and support many 2D and 3D CAD systems.
spring springs cylindrical spring compression spring helical spring en 13906-1 din 2089-1 din 2095 dynamic strength check.