eSketch PRO is a schematic capture and simulation application software specifically designed for the ultra fast rendition and simulation of frequency-shaping analog circuits such as preamplifiers, amplifiers, active filters, passive filters, crossovers, equalizers and tone controls. eSketch is a specialized program for circuits containing capacitors, inductors, resistors and op amps.

Solve Elec software is a free piece of software that helps you to study circuits in direct current and alternating current .
Solve Elec software is not a really circuit simulator software , but is very nice and good for students , which want to learn the basics of electronics .
Why is not a really circuit simulator software ? because you can not simulate directly circuits , without to type any equation . If you want to study some electronic circuit diagrams using Solve elec , you’ll need to know some basics equations ( depends of complexity of circuit ) .
Using this software you can :

The first version of NL for personal computers was developed in the early ‘90s as a tool for switching power supplies design. Since then NL has evolved into the Microsoft Windows®-based NL4, which has been used extensively by world-class engineers in different fields of electronics for almost 10 years. NL5 is the first version to be publicly available.

NL5 is circuit simulator software is a software that helps you to design non linear electronic circuits in a easy way .