The relay
The deliberately boring middle. Phones sleep, roam, and drop offline; the relay exists so messages arrive anyway. Its entire job is to hold a sealed envelope until the recipient's device picks it up, then forget it.
The relay (api.carrierpony.com) is a store-and-forward service. It receives end-to-end encrypted envelopes, queues them for the recipient's device, delivers them, and deletes them. It holds no accounts, no names, and no keys.
What it is
When you send a message, your phone hands the sealed envelope to the relay tagged with an opaque routing identifier. A push notification can wake the recipient's app to fetch it. Once delivered, the envelope is gone from the server.
Why it matters
Pure peer-to-peer messaging fails whenever both phones aren't online together, which for real humans is most of the time. A relay restores asynchrony. Designing it to know nothing keeps the convenience without creating a data trove.
Related terms
Common questions
What if the relay is hacked?
The attacker gets undelivered ciphertext and opaque identifiers. Messages remain end-to-end encrypted; there are no passwords, profiles, or contact graphs to steal, because none exist.
Can I run my own relay?
Not today. The app talks to api.carrierpony.com. The design keeps the relay untrusted, which is the property self-hosting usually seeks.
Get CarrierPony
Free private messaging and file transfer for iPhone and Android. No accounts, no tracking, no phone numbers.