| Magtech Industries | Nevada |
| Magtek Consulting Group, LLC | New Jersey |
| Magtek, Inc. | Kansas |
| Maguffin Microwave, LLC | Massachusetts |
| Mahalo Software, Inc. | |
| Mahalo Technologies, Inc. | Michigan |
| Maharishi International University Department of Computer Science | Iowa |
| Maharishi International University Department of Mathematics | Iowa |
| Mahoney Software Systems, LLC | California |
| MAI Computing, Inc. | Ohio |
| MAIA Biotechnology, Inc. | Illinois |
| MaiaHost | Virginia |
| MaiaTech | Texas |
| MaidStone Life Sciences | |
| Mail-List.com | Texas |
| Mail.com | |
| Mail2World, Inc. | California |
| MailArchiva | Texas |
| Mailbird | California |
| MailBug | California |
| MailChannels Corporation | |
| MailCharts | |
| MailChimp | Georgia |
| Maildrop | |
| MailerLite | California |
| MailerSend | New York |
| MailGun, Inc. | Texas |
| Mailigen | New York |
| Mailing List Manager Pro | California |
| MailMentor | |
| Mailmodo Technologies, Inc. | Delaware |
| Mailparser | Minnesota |
| Mailprotector | South Carolina |
| MailQuick | Texas |
| Mails.ai | Wyoming |
| Mailshake | Texas |
| Mailshell, Inc. | California |
| MailSite | California |
| Mailstrom | Maryland |
| Mailtrap | Connecticut |
| Mailtraq | Connecticut |
| MailXstream | Virginia |
| Main Line PC Consulting | Pennsylvania |
| Main Opt Marketing & Advertising | |
| Main Path | California |
| Main Resource, Inc. | California |
| Main Sequence Technology, Inc. | Ohio |
| Main Street Capital Corporation | Texas |
| Main Street Genome | |
| Main Street Marketing | |