Identifying the database location

In the Chrome browser that has the 529Renew extension installed, type (or copy/paste) chrome://version into the address bar and press Enter.

You will see one entry labelled "Profile Path". On a Windows system it will normally include folders like "...AppData\Local\Google\Chrome\User Data...". MacOS and Linux are different. At then end you will see either "default" or "Profile nn".

accessing the database files

In any system you should copy the entire Profile Path and open a file explorer there, or whatever procedure you use for navigating your hard drive. On a windows system you can open a "Run" box - hold down the "windows" key and press "r". Paste the entire profile path into the run bar and Enter (or click OK). You should see a pile of folders.

Look for one named "databases" and under that should be one named something like: "chrome-extension_hgckkjajmcmbificinfabmaelboedjic_0"

Within that folder should be a single file named simply with a number. In the unlikely situation of there being more than one file, check sizes and dates. In any case, copy whatever files are here into somewhere safe that you can access normally, and rename them something meaningful like Archive_529renew_2023-10-06.sqlite

Come November 2023, these database file in the profile path might be automatically deleted, or they might just be left there.

Accessing the data

There are various free utilities for access sqlite files on all platforms.

Exporting to a CSV from here is relatively straight-forward, but I won't bother with detail unless it becomes necessary.