diff --git a/78.md b/78.md
new file mode 100644
index 0000000..175f66b
--- /dev/null
+++ b/78.md
@@ -0,0 +1,21 @@
+NIP-78
+======
+
+Arbitrary custom app data
+-------------------------
+
+`draft` `optional` `author:sandwich` `author:fiatjaf`
+
+The goal of this NIP is to enable [remoteStorage](https://remotestorage.io/)-like capabilities for custom applications that do not care about interoperability.
+
+Even though interoperability is great, some apps do not want or do not need interoperability, and it that wouldn't make sense for them. Yet Nostr can still serve as a generalized data storage for these apps in a "bring your own database" way, for example: a user would open an app and somehow input their preferred relay for storage, which would then enable these apps to store application-specific data there.
+
+## Nostr event
+
+This NIP specifies the use of event kind `30078` (parameterized replaceable event) with a `d` tag containing some reference to the app name and context -- or any other arbitrary string. `content` and other `tags` can be anything or in any format.
+
+## Some use cases
+
+ - User personal settings on Nostr clients (and other apps unrelated to Nostr)
+ - A way for client developers to propagate dynamic parameters to users without these having to update
+ - Personal private data generated by apps that have nothing to do with Nostr, but allow users to use Nostr relays as their personal database
diff --git a/README.md b/README.md
index 8ee8b85..91ad0e8 100644
--- a/README.md
+++ b/README.md
@@ -36,6 +36,7 @@ NIPs stand for **Nostr Implementation Possibilities**. They exist to document wh
 - [NIP-57: Lightning Zaps](57.md)
 - [NIP-58: Badges](58.md)
 - [NIP-65: Relay List Metadata](65.md)
+- [NIP-78: Application-specific data](78.md)
 
 ## Event Kinds
 | kind          | description                      | NIP                     |
@@ -60,13 +61,14 @@ NIPs stand for **Nostr Implementation Possibilities**. They exist to document wh
 | 10002         | Relay List Metadata              | [65](65.md)             |
 | 22242         | Client Authentication            | [42](42.md)             |
 | 24133         | Nostr Connect                    | [46](46.md)             |
+| 30008         | Profile Badges                   | [58](58.md)             |
+| 30009         | Badge Definition                 | [58](58.md)             |
 | 30023         | Long-form Content                | [23](23.md)             |
+| 30078         | Application-specific Data        | [78](78.md)             |
 | 1000-9999     | Regular Events                   | [16](16.md)             |
 | 10000-19999   | Replaceable Events               | [16](16.md)             |
 | 20000-29999   | Ephemeral Events                 | [16](16.md)             |
 | 30000-39999   | Parameterized Replaceable Events | [33](33.md)             |
-| 30008         | Profile Badges                   | [58](58.md)             |
-| 30009         | Badge Definition                 | [58](58.md)             |
 
 ## Message types