diff --git a/services/blob/src/http/handlers/holders.rs b/services/blob/src/http/handlers/holders.rs
--- a/services/blob/src/http/handlers/holders.rs
+++ b/services/blob/src/http/handlers/holders.rs
@@ -1,4 +1,4 @@
-use actix_web::error::{ErrorBadRequest, ErrorForbidden};
+use actix_web::error::ErrorBadRequest;
 use actix_web::{web, HttpResponse};
 use comm_lib::auth::AuthorizationCredential;
 use comm_lib::blob::types::http::{
@@ -7,6 +7,7 @@
 };
 use tracing::{info, instrument, trace, warn};
 
+use crate::http::utils::verify_caller_is_service;
 use crate::service::BlobService;
 
 #[instrument(name = "assign_multiple_holders", skip_all)]
@@ -122,15 +123,3 @@
 
   Ok(())
 }
-
-/// Returns HTTP 403 if caller is not a Comm service
-fn verify_caller_is_service(
-  requesting_identity: &AuthorizationCredential,
-) -> actix_web::Result<()> {
-  match requesting_identity {
-    AuthorizationCredential::ServicesToken(_) => Ok(()),
-    _ => Err(ErrorForbidden(
-      "This endpoint can only be called by other services",
-    )),
-  }
-}
diff --git a/services/blob/src/http/handlers/metadata.rs b/services/blob/src/http/handlers/metadata.rs
new file mode 100644
--- /dev/null
+++ b/services/blob/src/http/handlers/metadata.rs
@@ -0,0 +1,17 @@
+use crate::{http::utils::verify_caller_is_service, service::BlobService};
+use actix_web::{web, HttpResponse};
+use comm_lib::{
+  auth::AuthorizationCredential, blob::types::http::BlobSizesRequest,
+};
+use tracing::instrument;
+
+#[instrument(name = "get_blob_sizes", skip_all)]
+pub async fn get_blob_sizes(
+  service: web::Data<BlobService>,
+  payload: web::Json<BlobSizesRequest>,
+  requesting_identity: AuthorizationCredential,
+) -> actix_web::Result<HttpResponse> {
+  verify_caller_is_service(&requesting_identity)?;
+
+  Ok(HttpResponse::NotImplemented().body("Not implemented yet"))
+}
diff --git a/services/blob/src/http/mod.rs b/services/blob/src/http/mod.rs
--- a/services/blob/src/http/mod.rs
+++ b/services/blob/src/http/mod.rs
@@ -13,6 +13,7 @@
 mod handlers {
   pub(super) mod blob;
   pub(super) mod holders;
+  pub(super) mod metadata;
 }
 
 pub async fn run_http_server(
@@ -47,10 +48,15 @@
       )
       .service(
         web::resource("/holders")
-          .wrap(auth_middleware)
+          .wrap(auth_middleware.clone())
           .route(web::post().to(handlers::holders::assign_holders_handler))
           .route(web::delete().to(handlers::holders::remove_holders_handler)),
       )
+      .service(
+        web::resource("/metadata/get_blob_sizes")
+          .wrap(auth_middleware)
+          .route(web::post().to(handlers::metadata::get_blob_sizes)),
+      )
   })
   .bind(("0.0.0.0", CONFIG.http_port))?
   .run()
diff --git a/services/blob/src/http/utils.rs b/services/blob/src/http/utils.rs
--- a/services/blob/src/http/utils.rs
+++ b/services/blob/src/http/utils.rs
@@ -1,3 +1,6 @@
+use actix_web::error::ErrorForbidden;
+use comm_lib::auth::AuthorizationCredential;
+
 /// Validates given identifier variable and returns HTTP 400
 /// in case of failure
 #[macro_export]
@@ -14,3 +17,15 @@
     }
   }};
 }
+
+/// Returns HTTP 403 if caller is not a Comm service
+pub fn verify_caller_is_service(
+  requesting_identity: &AuthorizationCredential,
+) -> actix_web::Result<()> {
+  match requesting_identity {
+    AuthorizationCredential::ServicesToken(_) => Ok(()),
+    _ => Err(ErrorForbidden(
+      "This endpoint can only be called by other services",
+    )),
+  }
+}
diff --git a/shared/comm-lib/src/blob/types.rs b/shared/comm-lib/src/blob/types.rs
--- a/shared/comm-lib/src/blob/types.rs
+++ b/shared/comm-lib/src/blob/types.rs
@@ -11,6 +11,8 @@
 /// If you edit the definitions in one file,
 /// please make sure to update the corresponding definitions in the other.
 pub mod http {
+  use std::collections::HashMap;
+
   use serde::{Deserialize, Serialize};
 
   pub use super::BlobInfo;
@@ -93,6 +95,22 @@
       }
     }
   }
+
+  // Blob metadata endpoint types
+  // NOTE: These are accessible from other services and should not be exposed
+  // to `lib/types/blob-service-types.js` JS definitions.
+
+  #[derive(Serialize, Deserialize, Debug)]
+  #[serde(rename_all = "camelCase")]
+  pub struct BlobSizesRequest {
+    pub blob_hashes: Vec<String>,
+  }
+
+  #[derive(Serialize, Deserialize, Debug)]
+  #[serde(rename_all = "camelCase")]
+  pub struct BlobSizesResponse {
+    pub blob_sizes: HashMap<String, u64>,
+  }
 }
 
 /// Blob owning information - stores both blob_hash and holder