GIT is used as an underlying configuration management tool for all documentation and coding. It helps to manage version and track deliveries, retrieve them, reproduce issues.
JIRA is used for recording defects and taking it through quick and useful closure cycle with required documentation on change committed.
Documentation depends on preferred customer medium. DKT can do it in following tools: a. Microsoft Office b. LibreOffice c. Latex d. Mark-Down + HTML and basic CSS/JS
Last one being the most preferred one considering reusability, traceability of information.
Due to stringent, routine configuration management elements, it is always easy to transfer of information to other vendor, if at all that happens.