Scan once. Every scan after gives you the names: who left, who's new, who never followed back. Instagram and GitHub, entirely on your device.
Open source No account Nothing leaves your device
01The problem
Instagram shows 1,284, then 1,281. Three people left, and the platform keeps no record of who they were. FollowLens keeps that record for you.
02Two platforms
Both platforms get the complete product: scans, comparisons, analytics and exports. Only the way each list has to be read is different.
Instagram loads its lists as you scroll, so rows you have not reached yet do not exist. FollowLens opens the list, walks it to the end, and starts again if a pass finishes below the profile’s own count.
GitHub renders its lists on the server and pages them with a Next link. FollowLens follows that link page by page, and uses GitHub’s public REST API where it can.
03Not only your account
Did your ex, your crush, that friend, your boss or your rival follow someone new this week?
FollowLens scans whatever profile you have open, so the account does not have to be yours. Point it at any that already opens for you — public, or private and one you follow — and it tracks that account like your own: who they followed, who they dropped, and who left them.
If the profile opens for you, it scans: any public account, or a private one you follow. Press Start and it becomes a tracked account of its own.
Their following list, diffed between two scans. The names that were not there last time are exactly who they have followed since, in order.
The same arithmetic in reverse, over their followers: the names that were there last time and are gone now — everyone who left them since.
It sees exactly what your own session sees: a public list, or a private one you already have access to. A list that will not open for you will not open for it either. Nothing is sent anywhere, and the profile you scan is never notified, because there is no server to notify it.
04How it works
Nothing runs on its own. You open the profile, you start the scan, and you save it.
Yours, or any that already opens for you, in the session you are signed in with. You do not have to find the list — Auto-Collect opens the followers or following one itself.
Auto-Collect walks the list for you. A badge on the page shows progress and stops it whenever you want.
The first scan becomes your baseline. Every scan after it answers the question the platform will not.
05What you see
Every category is one click away, and every row opens the profile.
06The app
The popup starts scans and shows the headline numbers. Everything else lives in a full page with its own sidebar: history, comparisons, analytics and settings.
07Honesty
A platform’s own header count can include accounts its list endpoint never returns, such as restricted or deactivated ones. A tracker that rounds up produces a wrong “not following back” list and never admits it.
FollowLens shows what it collected against what was expected, and will not call a list complete when it knows it is not.
08Analytics
A growth chart, the change at each scan, a date range you can narrow, and a side-by-side view of any two scans you have taken.
Pick two dates, see exactly what changed between them, in both directions.
Each tracked separately, on either platform, with its own history and labels.
Hide the accounts you don't want to keep seeing, without deleting the scan.
09Export
Four formats, the columns you choose, in your language. That includes a printable report with the growth chart, and a full JSON backup that restores your history on another machine.
Export is also the way out. Nothing is held back to keep you here: the JSON backup is your history in full, it restores on another machine, and it is still readable the day you uninstall. An app that owns your data does not hand it over that easily.
10Privacy
FollowLens has no backend, no analytics and no account system. Your scans live in your browser’s own database, and the only requests it makes go to the platform you already have open.
Every request it makes is written down, and the code that makes them is public. Read the privacy policy
11The alternative
Most free follower apps ask for your password, upload your list to a server you cannot see, and charge you to unblur the answer. That business model needs your data. FollowLens does not have one.
| FollowLens | Typical follower app | |
|---|---|---|
| Asks for your password | FollowLensNever. There is no login. | Typical follower appUsually, or an OAuth token |
| Where your list goes | FollowLensYour browser's own database | Typical follower appTheir server, kept indefinitely |
| Cost of the answer | FollowLensFree, all of it | Typical follower appBlurred until you subscribe |
| When a scan is incomplete | FollowLensSays so, and by how much | Typical follower appShows the list anyway |
| Auditable | FollowLensMIT, every line on GitHub | Typical follower appClosed and minified |
12FAQ
No, and there is nowhere to enter one. FollowLens has no account system. It reads the lists on the profiles you open, in your own signed-in browser session, which means it can only ever see what you can see.
Yes, as long as it opens for you. FollowLens scans whatever profile you have open and finds the followers or following list itself, so a public profile — or a private one you already follow — becomes a tracked account with its own history, comparisons and exports. An account that will not open for you cannot be read by the extension either.
Yes, and not as an afterthought. GitHub gets the same scans, comparisons, analytics and exports as Instagram. FollowLens reads the server-rendered followers and following tabs, and prefers the public REST API, which needs no session.
Auto-Collect produces the same requests your own scrolling does, paced irregularly rather than on a fixed beat. Automated collection may still conflict with a platform’s terms of service, so FollowLens keeps it opt-in, visible and stoppable. The choice is yours.
A platform’s header count can include accounts its list endpoint never returns, such as restricted or deactivated ones. Rather than round up, FollowLens shows what it collected against what was expected and tells you the list is not fully loaded.
On the machine you scanned with, in your browser’s IndexedDB. There is no server, no sync and no account, which means a scan taken on your laptop will not appear on your phone unless you export it and move it yourself.
Yes, and it is MIT licensed. There is no paid tier, no upsell and no telemetry to sell. If it is useful to you, a star on GitHub is the entire business model.
Install it, run one scan, and the next scan gives you the answer.
Chrome and Brave. No account, no permissions beyond the two sites it reads. Or install from source