Instoryview
Instoryview helps creators and marketers keep a dated record of changes in supported public Instagram accounts. It compares saved followers and following lists to show new follows, new followers, unfollows and lost followers in a timeline.
The distinction that matters: a change is detected between checks. It is not an exact timestamp of the Instagram action, and the service cannot recreate arbitrary history from before tracking began.
It runs in the browser and does not ask for an Instagram password. Ongoing tracking requires an Instoryview account. Private accounts are not supported; follower tracking also excludes verified accounts and accounts above 100,000 followers.
There is a free credit-based plan for one tracked account, with paid plans starting at $9.90/month. Instoryview is independent and is not affiliated with Meta or Instagram.