diff --git a/crates/bl/src/fetch.rs b/crates/bl/src/fetch.rs
index 7c25b25..0f0a576 100644
--- a/crates/bl/src/fetch.rs
+++ b/crates/bl/src/fetch.rs
@@ -1,7 +1,10 @@
 use core_types::{PhotoGroup, PhotoThumbnailDisplayParams};
-use leptos::{server, ServerFnError};
+use leptos::{server, server_fn::codec::Json, ServerFnError};
 
-#[server]
+#[server(
+  input = Json,
+  output = Json,
+)]
 #[cfg_attr(feature = "ssr", tracing::instrument)]
 pub async fn fetch_user_owned_photo_groups(
   user_id: core_types::UserRecordId,
@@ -43,7 +46,10 @@ pub async fn fetch_user_owned_photo_groups(
   })
 }
 
-#[server]
+#[server(
+  input = Json,
+  output = Json,
+)]
 #[cfg_attr(feature = "ssr", tracing::instrument)]
 pub async fn fetch_photo_group(
   photo_group_id: core_types::PhotoGroupRecordId,
@@ -77,7 +83,10 @@ pub async fn fetch_photo_group(
   })
 }
 
-#[server]
+#[server(
+  input = Json,
+  output = Json,
+)]
 #[cfg_attr(feature = "ssr", tracing::instrument)]
 pub async fn fetch_user(
   user_id: core_types::UserRecordId,
@@ -110,7 +119,10 @@ pub async fn fetch_user(
   })
 }
 
-#[server]
+#[server(
+  input = Json,
+  output = Json,
+)]
 #[cfg_attr(feature = "ssr", tracing::instrument)]
 pub async fn fetch_photo_thumbnail(
   photo_id: core_types::PhotoRecordId,
diff --git a/crates/bl/src/qr_code.rs b/crates/bl/src/qr_code.rs
index 9ae6e0b..1c4a4fc 100644
--- a/crates/bl/src/qr_code.rs
+++ b/crates/bl/src/qr_code.rs
@@ -1,4 +1,4 @@
-use leptos::{server, ServerFnError};
+use leptos::{server, server_fn::codec::Json, ServerFnError};
 
 /// Generate a QR code from the given data. Returns base64 encoded PNG data.
 #[cfg(feature = "ssr")]
@@ -21,7 +21,10 @@ pub fn generate_qr_code_inner(data: &str) -> color_eyre::eyre::Result<String> {
   Ok(data)
 }
 
-#[server]
+#[server(
+  input = Json,
+  output = Json,
+)]
 #[cfg_attr(feature = "ssr", tracing::instrument)]
 pub async fn generate_qr_code(data: String) -> Result<String, ServerFnError> {
   generate_qr_code_inner(&data).map_err(|e| {