This helps count the number of users accessing your service in a very privacy friendly way.

• The main server calls this secondary server for every request
  • It passes a hashed version of the IP address in this request
• This user counter hashes and salts the (already hashed) IP and saves it in a set in memory
• Every 48 hours, the size of the set is saved as the user count
  • The set is then cleared
  • A new salt is generated

This is privacy friendly for several reasons:

• IPs are only stored hashed and salted with the salt rotating every 48 hours
• Hashed IPs are not associated with the contents of the request
• Data is only stored in memory

Usage

Install nodejs and npm

npm install

npm start

How to use

This was build for SponsorBlock, but can be used by any service.

Simply send a request to the following endpoint for every request recieved on your service. You must hash the IP first on the service-side before sending it.

POST /api/v1/addIP?hashedIP=<hashed-ip-goes-here>

Then, you can get the users using the following request:

GET /api/v1/userCount

Response:

{
    "userCount": number
}

It will update every 48 hours and return the max number of unique users in the last 28 days.