| 28778 | Copy | ZX81 1K | English |
| 41208 | Copy Function | ZX81 16K | English |
| 40110 | Copycat | ZX81 16K | English |
| 35591 | Correlation Coefficient | ZX-Spectrum 48K | English |
| 39967 | Correlation Coefficient and Regression Analysis | ZX81 16K | English |
| 8060 | Cotavilidad | ZX-Spectrum 48K | Spanish |
| 31030 | Crap Factor | ZX-Spectrum 16K | English |
| 39700 | Crashproof Your ZX81 | ZX81 16K | English |
| 40456 | Cribboard | ZX81 16K | English |
| 40716 | Cricket Score | ZX81 16K | English |
| 29171 | Critical Path Analysis | ZX81 16K | English |
| 19709 | Cubos | ZX-Spectrum 48K | Spanish |
| 17260 | Cuentas Bancarias | ZX-Spectrum 48K | Spanish |
| 41563 | Currency Conversion | ZX81 16K | English |
| 40060 | DATA Builder | ZX-Spectrum 48K | English |
| 40312 | DATA Read | ZX-Spectrum 48K | English |
| 40623 | DATA Statement Simulation | ZX80 | English |
| 39938 | DEF FN Simulation | ZX81 16K | English |
| 41420 | DEFMAG | ZX81 16K | English |
| 41762 | DELETE GGMI | ZX81 16K | Portuguese |