Hbfree
- Free command line RF/microwave harmonic balance circuit simulator, for analog nonlinear circuits simulation with diode and MESFET nonlinear elements.
- http://hbfree.sourceforge.net/

Schematica
- Windows software for design of active filters and linear circuit simulation
- http://www.schematica.com

Designer's Guide Consulting
- Provides verification and simulation services to companies involved in integrated circuit design. Includes information resource about modeling, theory and analysis, as well as a discussion forum.
- http://www.designers-guide.com

AC Microwave GmbH
- Offers the LINMIC+/N microwave and RF IC design suite; mostly electromagnetics-based.
- http://www.linmic.com/

Cyme International
- Offer software for various analyses, design, parameter calculation and distribution.
- http://www.cyme.com

Avista Design Systems
- Tools to simplify analog and RF design.
- http://www.avista.com

EDSA Micro Corporation
- Electrical power systems design software.
- http://www.edsa.com

Infolytica
- Offer electromagnetics design software for both low and high frequency applications. Products include MagNet, ElecNet and FullWave.
- http://www.infolytica.com