The ShareGate migration tool can crawl through your selected target to list all your site collections. You can take action on these site collections once the report is finished running.
- Click All reports.
- Click Site collection report under Built-in reports.
- Select the target of the report.
- Click Next.
- Set your options.
- Click Schedule or Run now.
- You will now get a list of all site collections within your selected target.
To learn how to modify a report and save it (add filters and add/remove columns), see Custom reports.
For more on reports, see Reporting options.