After implementing ioet/time-tracker-backend#169 please call the endpoint /time-entries/summary adding the timezoneOffset query parameter as follows:

GET /time-entries/summary?time_offset={offsetInMinutes}

offsetInMinutes can be get easily with the following js function:

Date.prototype.getTimezoneOffset()

More info available here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/getTimezoneOffset