Delivery and outages

Reliable before fast: an accepted message is never dropped.

When a message counts as sent

Each message is written to several nodes at once, and counts as sent only when a majority of them have stored it. From then on it isn't dropped.

During an outage

If nodes go down, messages wait. They arrive once enough nodes are reachable again. Your device saves a message before it confirms receipt, so a crash on your side doesn't lose one either.

How we test it

We run long tests that crash nodes, wipe them and cut them off from each other on purpose, while messages flow. In our latest runs, more than 90,000 messages were sent through those failures and none was lost.