There is no specific integration of projeqtor with Mantis.
Moreover, integration will depends on your need and may differ between users :
 - import Mantis tickets in ProjeQtOr
 - import Mantis tickets in ProjeQtOr, including updates (complex)
 - import ProjeQtOr tickets in Mantis
 - import ProjeQtOr tickets in Mantis, including updates (complex)
 - Bi-directionnal import (complex)
 - Bi-directional , including updates (very complex)

ProjeQtOr proposes an API so that you can read and update projeqtor data from remote application, but this will required coding on Mantis side.
We are also working on webHooks, so that some events in projeqtor will be able to trigger some action (call an URL) on remote application, but then again , some coding will be required.

Hello,
I saw on your roadmap tracking database that a WebHooks management plugin is given as done. Does this mean that the webhook functionality is already available ? If not, when do you plan to make it actually available, to buy or not, on your Plugins page? Thank

Webhooks plugin is ready to be deployed.
We plan to pack it into some "interface" plugin, including Webkhooks and github integration, so we need to finish this last one to deploy both.

Can I ask you on which version exactly will we see WebHooks functionality integrated ? I thought it was coming with vers. 10 (by the way, thanks for the improvement in login speed), but it doesn't seem like that to me. Or when, approximately, will you make available a new plugin for WebHook integrations (together GitHub): 3 months, 6 months, 1 year, 2 years ?
Thanks for all the clarifications you can give me

WebHooks functionality integrated

It will be a plugin. The plugin is ready, waiting for Github integration to be deployed together.
Hope it will be deployed during september.