Vlexx GmbH (stylized in lowercase in its logo) is a rail transport company based in Mainz, Rhineland-Palatinate, Germany; it is a subsidiary of the Regentalbahn, which in turn has been part of the Italian state railway Ferrovie dello Stato (FS) since 2011 via its parent company Netinera.

The company was founded as DNSW in 2012 and derived from the so-called "diesel network southwest'", whose cornerstones are the Rhineland-Palatinate cities of Mainz, Koblenz, Worms, Kaiserslautern and Idar-Oberstein as well as Saarbrücken in the Saarland and Frankfurt am Main in Hesse.

In December 2016, an additional Regional-Express line was introduced on the Kaiserslautern-Bad Kreuznach-Bingen-Koblenz route, which means that 6.4 million train-kilometres per year now have to be covered.

[6] When the operation started on 15 December 2014, there were massive train cancellations and, in some cases, delays lasting several hours.

This affected five connections that were taken over by DB Regio and Transregio during the summer holidays in Rhineland-Palatinate or were completely cancelled.

[11] On January 9, 2017, the Ministry of Economy, Labour, Energy and Transport of the Saarland announced that vlexx had won Los 2 of the E-Netz Saar-RB, comprising 2.3 million train kilometers.