VOCALOID-flex is a particular branch of the VOCALOID software which was designed for talking, presented in February 2010. It is more delicate to edit than the normal VOCALOID engine. It can be used in conjunction with software suits such as VTalk. It differs from the normal engine, which focuses only on singing, it however works in the same manner of assembling phonetic data. Despite the fact it can now be commercially bought, much of the details of the engine are largely unknown. Its development was to further extend the usage of the VOCALOID software, making it feasible to use the software for private licensing.
Gachapoid and CV-4Cβ are two of the only voicebanks known to use VOCALOID-flex. Further voicebanks using the software have not been confirmed. It was also used in part with the game Metal Gear Solid: Peace Walker. It was used for several mecha known as "Gear" within the game, the most notable being "ZEKE".
The state of this project is unknown, though VOCALOID3 naturally has the capabilities to do talking more easily than VOCALOID2.