There are multiple reasons for exporting your ascents from 8a.nu. First and foremost to create a backup copy of your data in a neutral format and then of course to transfer your ascent data to a different service such as theCrag.
8a.nu has a history of making undocumented changes to their data model and export functions but here we try to offer you a current and functioning tool to get YOUR data out of 8a.nu. If you find it not working at one point in time, please contact support.
All you have to do is identify your 8a.nu account name (to do so log into 8a.nu with your account and look at the URL in your browser, it looks like this: www.8a.nu/user/ACCOUNT-NAME) and paste it into the form below. If you have a private 8a profile, you have to change it (temporary) to a public profile before the export.
Click Export Logbook and wait for the data to be displayed. Once the data are displayed, simply click on Download CSV and you may download the csv-file that you can either store for later reference or directly import on theCrag (see Import your logbook).