Gaztransport & Technigaz SA is a French multinational naval engineering company with headquarters in Saint-Rémy-lès-Chevreuse, France.

Trading as the GTT Group, the company is an engineering organization specializing in membrane containment systems dedicated to the transport and storage of liquefied gas worldwide. GTT has developed and patented multiple solutions for the liquefied gas industry, in particular for Liquefied Natural Gas (LNG). The company is the sole supplier of maritime containment tanks for LNG.

The current company was established through a merger between rival companies Gaztransport SA and Technigaz SA in 1994.

On the 27 February 2014 the GTT Group was listed on the Euronext Paris stock exchange.