PearCircle

PearCircle has no server. Your circle's data, every location update, every place, every trip, lives only on the devices in that circle. When those devices need to share an update, they talk to each other directly, encrypted end to end. No company, including PeerLoom, can read your location because no company ever receives it.

In most location sharing apps, your phone sends your location to a central server and the server forwards it to your friends and family. The server reads everything. In a peer to peer app, two phones talk directly to each other. There is no server in the middle.

Think of email versus a handwritten letter. Email routes through several companies that could read it. A letter goes from your hand to your recipient's hand. PearCircle works more like the letter.

The obvious question: if there is no server, how do the devices in a circle know how to reach each other?

PearCircle uses a distributed hash table, or DHT, the same technology that powers BitTorrent. A DHT is a phone book that no one company owns. It is spread across thousands of participating devices around the world. When devices in a circle come online, they each ask the DHT "has anyone seen my circle?" and the DHT helps them connect.

Crucially, the DHT only helps devices find each other. It never sees the data they exchange.

PearCircle draws the map using public tiles served by an open tile provider (currently OpenFreeMap). Your device asks the provider for tile coordinates only. The tile request is a stateless "give me square (z, x, y)". It carries no information about who you are, what circle you are looking at or whose pin is on the map.

Tiles you have already viewed are cached on your device so the map keeps working offline.

PearCircle stores the following locally on each device in a circle:

• Your profile name and optional avatar.
• Your current and recent location updates, broadcast to the circle.
• The Places (geofences) defined in that circle and the arrival or departure transitions recorded as members cross them.
• Trips your device has recorded, shared to a circle only if you opt in.
• The cryptographic keys that identify your device to the other devices in the circle.

All of it is stored on the devices in the circle. None of it is uploaded to PeerLoom or any third party.

Two things protect the data flowing between devices in a circle:

• End to end encryption. Everything the devices exchange is encrypted with keys that only the circle members hold. If someone intercepts the traffic on your Wi-Fi, your mobile carrier or anywhere else on the internet, they see scrambled bytes.
• Cryptographic signing. Every location update, place change and trip is signed by the device that wrote it. Other devices only apply updates that carry a valid signature from a known member. A stranger cannot inject a fake position, even if they guessed your circle address.

Most location sharing apps (Life360, Find My and others) ask you to create an account and upload everyone's position to the company's servers. That model has real costs:

• The company can read every place you and your family go. Some sell that data to advertisers or data brokers.
• If the company gets hacked, your location history leaks along with everyone else's.
• If the company shuts down or pivots away from location sharing, your setup breaks.
• Outages on the company's servers knock sharing offline for everyone at once.

PearCircle trades the convenience of a cloud backend for privacy and independence. There is no account to hack, no server to leak, no subscription to cancel and no company to shut down.

Peer to peer is not magic. Honest tradeoffs:

• Both devices need to be online at the same time to sync in real time. A location update propagates to a peer the next time their device connects. This is usually within seconds but can be longer if a peer is offline.
• No web dashboard. There is no website where you can log in and see your circle, because there is no server to back one. Everything happens in the app on your device.
• No cross device cloud backup. If you lose your device and had not exported a backup, you will need to rejoin your circles from a fresh install.

These are deliberate choices. A cloud backend would solve all three at the cost of everything the peer to peer design protects.

You do not have to take our word for any of this. PearCircle is fully open source. The complete code, including the sync layer and the encryption code, is published at github.com/peerloomllc/pearcircle.

• Full privacy policy
• Hypercore Protocol. The peer to peer technology that powers PearCircle sync.