---
---
{{% added-in v=4 %}} The event ID is the [reference
hash](/server-server-api#calculating-the-reference-hash-for-an-event) of
the event encoded using [URL-safe unpadded
Base64](/appendices/#url-safe-unpadded-base64).

Event IDs are still prefixed with `$` and might result in looking like
`$Rqnc-F-dvnEYJTyHq_iKxU2bZ1CI92-kuZq3a5lr5Zg`.