Here’s a short list of some Maatkit users who’ve either given permission to be listed, or have praised Maatkit in a public place.  If you’d like to be listed here, please say something on the mailing list!

User Testimonial
BBC The BBC is the largest broadcasting organisation in the world. Its mission is to enrich people’s lives with programmes that inform, educate and entertain.
Facebook helps you connect and share with the people in your life. Maatkit helps Facebook do what they do.
Linden Lab, the creators of Second Life, used Maatkit to help ensure that their MySQL upgrade project would go smoothly:

We also needed to know that our data would be sound, that none of the SQL syntax changes or order-dependent execution changes between major versions would bite us, and that we weren’t going to run into any replication bugs. For this we used the Maatkit toolset.

GoDaddy Logo “mk-query-digest has made it much easier to emulate production workloads. Thank you for a great tool.” — Rob Wultsch,
“We use it in, the biggest social network in Spain.” — Alex Barrera
MySQL Kristian Köhntopp, Principal Consultant, MySQL AB found that replication was prone to invisible errors, but mk-table-checksum could find them: “Indispensable… MySQL replication should really have something built into it that does something equivalent.”
Ronald Bradford, MySQL expert Ronald was looking for a way to find all queries being executed on his server in real-time, and mk-query-digest’s ability to analyze TCP traffic fit the bill perfectly: “This tool has been designed by MySQL DBA’s for MySQL DBA’s.”
MySQL “Tree-like explain is something I always wanted to have.” — Timour Katchaounov, MySQL Optimizer Team