- Codasip Ltd.
- Codefast, Inc
- Codenomicon Oy
- CodeSourcery Inc.
- CoFluent Design
- Comdisco Systems Inc.
- ComLSI
- Compact Model Coalition
- Compass Design Automation
- Compiled Designs GmbH
- Computer Simulation Technology GmbH
- Computervision, Inc.
- Computing-Tabulating-Recording Company
- Concept Engineering GmbH
- Context Corporation
- Contour Design Systems, Inc.
- Conversant Intellectual Property Management
- Cooper and Chyan Technology Inc.
- Cortus S.A.S.
- Cosmic Circuits
- CoSoft Ltd.
- Council of EDA Standards Committee
- Coventor, a Lam Research Company
- CoverMeter Tool
- CoWare LLC
- Coyote Systems
- Cre8 Ventures
- Credence Systems Corporation
- Critical Blue
- Crosslight Software, Inc.
- CyberOptics, a Nordson Test & Inspection company
- CycleC and other technology assets
- Cycuity
- Cynapps
- D2S
- Daisy Systems Corporation
- Dassault Systèmes
- Dasys
- Data I/O
- Datalink Far East, Ltd
- Dazix
- DDE-EDA A/S
- Deerbrook Systems Inc.
- Defacto Technologies
- Defense Advanced Research Agency (DARPA)
- DelSoft India Pvt. Ltd
- DELTA Microelectronics
- Denali Software, Inc.
- Desantage Corporation
- Descartes Automation Systems
