| ManchaNet, S.L.L. | Ciudad Real |
| MandanWebs.com | Barcelona |
| Mansion Studios, S.L. | Balearic Islands |
| Mantedif | Madrid |
| Mantenimiento Informático | Madrid |
| Mantra Internet, S.L.N.E. | Madrid |
| Many-Worlds | |
| MAP | Barcelona |
| Maquetas Tech | Madrid |
| Maquinas el Siete, S.A. | Madrid |
| Marbella Website Design & Development | |
| Marfeel | Barcelona |
| Marfeel Solutions, S.L. | |
| Margen Multimedia, S.L. | Madrid |
| Marina Tel and Data, S.L. | Barcelona |
| Marketalia | Madrid |
| Marketeros Web | Madrid |
| marketgoo.com | Madrid |
| MarketiNet Agencia de Marketing Digital, S.L. | Madrid |
| marketingpublicidad | Sevilla |
| MarsBased, S.L. | |
| Marta Díaz Berbel | |
| Marzo | Madrid |
| MAS2D | Málaga |
| MasBytes, S.L. | Navarre |
| MasOrange, S.L. | |
| MasQSoft Consultores, S.L. | Madrid |
| Mastac, S.L. | Barcelona |
| Master Disseny | Barcelona |
| Master N. Automatismos, S.L. | Navarre |
| Mastoner Distribución Informática, S.L.U. | Madrid |
| Masvoz Telecomunicaciones Interactivas, S.L.U. | Barcelona |
| Mata Canaria, S.L. | Las Palmas |
| Matradi, S.L. | Valencia |
| Matrix Development System, S.A. | Barcelona |
| Matrix Electronica, S.L. | Madrid |
| Mawell Net System | Madrid |
| Max Planck | |
| Max Programming, LLC | Alicante |
| MAXIMA Graphics | |
| MBS Informáticas | Madrid |
| MC Consulting Informático | Murcia |
| MCB Informática | Madrid |
| MCR Info Electronic, S.L. | Madrid |
| Mdtel | Madrid |
| Mecambioamac | Barcelona |
| Mecemsa Consultores, S.A. | Alicante |
| Media Marketing Internet, S.L. | Barcelona |
| Mediaclick conversión, S.L. | Barcelona |
| Mediacloud | Madrid |