| cwa | Castelware Inventory Audit Data |
| cwdb | ClarisWorks Database |
| cwie | CodeWarrior Module Data |
| cwm | Common Warehouse Metamodel File |
| cwpb | CopyWrite Project Binder Data |
| cwr | WrapCandy Template |
| cww | Crossword Weaver Puzzle |
| cwx | CodeWallet Pro 5 Form |
| cxa | ANSYS Fluent Solution Animation File |
| cxb | Custody X Change CXB Data |
| cxc | Custody X Change Data |
| cxd | Hamamatsu SimplePCI Data |
| cxe | Common XML Envelope Data |
| cxf | Google Picasa Collage |
| cxf | Coordinates Export Format |
| cxf | SciFinder Chemical eXchange Format Data |
| cxi | Coherent X-ray Imaging Data |
| cxk | WSCAD Connection List |
| cxl | Tekla Structural Designer Neutral Data |
| cxm | QuadColor Color Correction Master Data |
| cxml | Silverlight PivotViewer XML Data |
| cxo | CXInsight Export Data |
| cxp | Crocodile Physics Simulation Data |
| cxr | FMAT Plate Results Data |
| cxs | ConciseXML Format Data |
| cxt | Crocodile Technology Simulation Data |
| cxv | Custody X Change Data |
| cy3 | Cytel StatXact 5.0 Data |
| cyb | Cytel Studio Batch |
| cyd | LogXact Data |
| cyd | Cytel Studio Data |
| cydb | Alteryx Designer Calgary Database |
| cyg | CyGem Pollux Data |
| cyidx | Alteryx Designer Calgary Database Index |
| cyl | Cytel LogXact Data |