diff --git a/backend/config-e2e.yml b/backend/config-e2e.yml
index 04fe344a..a49ab287 100644
--- a/backend/config-e2e.yml
+++ b/backend/config-e2e.yml
@@ -1,6 +1,6 @@
 database:
   databases_directory_path: databases
-  max_connections: 12
+  max_connections_per_vault: 12
 
 server:
   host: 0.0.0.0
@@ -13,7 +13,7 @@ users:
   - name: admin
     token: test-token-change-me
     vaults: 
-      all: true
+      allow_access_to_all: true
 
   - name: test
     token: other-test-token
diff --git a/backend/sync_server/src/app_state/database.rs b/backend/sync_server/src/app_state/database.rs
index fa7f35b0..2c2cfced 100644
--- a/backend/sync_server/src/app_state/database.rs
+++ b/backend/sync_server/src/app_state/database.rs
@@ -73,7 +73,7 @@ impl Database {
             .journal_mode(sqlx::sqlite::SqliteJournalMode::Wal);
 
         let pool = SqlitePoolOptions::new()
-            .max_connections(config.max_connections)
+            .max_connections(config.max_connections_per_vault)
             .test_before_acquire(true)
             .connect_with(connection_options)
             .await
diff --git a/backend/sync_server/src/config/database_config.rs b/backend/sync_server/src/config/database_config.rs
index b3d2fad7..ef26a09d 100644
--- a/backend/sync_server/src/config/database_config.rs
+++ b/backend/sync_server/src/config/database_config.rs
@@ -3,15 +3,15 @@ use std::path::PathBuf;
 use log::debug;
 use serde::{Deserialize, Serialize};
 
-use crate::consts::{DEFAULT_DATABASES_DIRECTORY_PATH, DEFAULT_MAX_CONNECTIONS};
+use crate::consts::{DEFAULT_DATABASES_DIRECTORY_PATH, DEFAULT_MAX_CONNECTIONS_PER_VAULT};
 
 #[derive(Debug, Deserialize, Serialize, Clone)]
 pub struct DatabaseConfig {
     #[serde(default = "default_databases_directory_path")]
     pub databases_directory_path: PathBuf,
 
-    #[serde(default = "default_max_connections")]
-    pub max_connections: u32,
+    #[serde(default = "default_max_connections_per_vault")]
+    pub max_connections_per_vault: u32,
 }
 
 fn default_databases_directory_path() -> PathBuf {
@@ -19,16 +19,16 @@ fn default_databases_directory_path() -> PathBuf {
     PathBuf::from(DEFAULT_DATABASES_DIRECTORY_PATH)
 }
 
-fn default_max_connections() -> u32 {
-    debug!("Using default max connections: {DEFAULT_MAX_CONNECTIONS}");
-    DEFAULT_MAX_CONNECTIONS
+fn default_max_connections_per_vault() -> u32 {
+    debug!("Using default max connections: {DEFAULT_MAX_CONNECTIONS_PER_VAULT}");
+    DEFAULT_MAX_CONNECTIONS_PER_VAULT
 }
 
 impl Default for DatabaseConfig {
     fn default() -> Self {
         Self {
             databases_directory_path: default_databases_directory_path(),
-            max_connections: default_max_connections(),
+            max_connections_per_vault: default_max_connections_per_vault(),
         }
     }
 }
diff --git a/backend/sync_server/src/config/user_config.rs b/backend/sync_server/src/config/user_config.rs
index c3afca14..4ee7c72d 100644
--- a/backend/sync_server/src/config/user_config.rs
+++ b/backend/sync_server/src/config/user_config.rs
@@ -1,6 +1,10 @@
+use std::default;
+
 use rand::{Rng as _, distributions::Alphanumeric, thread_rng};
 use serde::{Deserialize, Serialize};
 
+use crate::app_state::database::models::VaultId;
+
 #[derive(Debug, Deserialize, Serialize, Clone)]
 pub struct UserConfig {
     #[serde(default = "default_users")]
@@ -17,6 +21,7 @@ impl UserConfig {
 pub struct User {
     pub name: String,
     pub token: String,
+    pub vault_access: VaultAccess,
 }
 
 impl Default for UserConfig {
@@ -27,10 +32,25 @@ impl Default for UserConfig {
     }
 }
 
+#[derive(Debug, Deserialize, Serialize, Clone, Default)]
+#[serde(rename_all = "snake_case", tag = "type")]
+pub enum VaultAccess {
+    #[default]
+    AllowAccessToAll,
+
+    AllowList(AllowListedVaults),
+}
+
+#[derive(Debug, Deserialize, Serialize, Clone, Default)]
+pub struct AllowListedVaults {
+    pub allowed: Vec<VaultId>,
+}
+
 fn default_users() -> Vec<User> {
     vec![User {
         name: "admin".to_owned(),
         token: get_random_token(),
+        vault_access: VaultAccess::default(),
     }]
 }
 
diff --git a/backend/sync_server/src/consts.rs b/backend/sync_server/src/consts.rs
index 2d3bec55..1453f25a 100644
--- a/backend/sync_server/src/consts.rs
+++ b/backend/sync_server/src/consts.rs
@@ -2,6 +2,6 @@ pub const DEFAULT_CONFIG_PATH: &str = "config.yml";
 pub const DEFAULT_DATABASES_DIRECTORY_PATH: &str = "databases";
 pub const DEFAULT_HOST: &str = "127.0.0.1";
 pub const DEFAULT_PORT: u16 = 3000;
-pub const DEFAULT_MAX_CONNECTIONS: u32 = 12;
+pub const DEFAULT_MAX_CONNECTIONS_PER_VAULT: u32 = 12;
 pub const DEFAULT_MAX_BODY_SIZE_MB: usize = 4096;
 pub const DEFAULT_MAX_CLIENTS_PER_VAULT: usize = 256;
diff --git a/backend/sync_server/src/errors.rs b/backend/sync_server/src/errors.rs
index 5aec9c32..31538107 100644
--- a/backend/sync_server/src/errors.rs
+++ b/backend/sync_server/src/errors.rs
@@ -24,7 +24,7 @@ pub enum SyncServerError {
     NotFound(#[source] anyhow::Error),
 
     #[error("Unauthorized: {0}")]
-    Unauthorized(#[source] anyhow::Error),
+    Unauthenticated(#[source] anyhow::Error),
 
     #[error("Permission denied error: {0}")]
     PermissionDeniedError(#[source] anyhow::Error),
@@ -37,7 +37,7 @@ impl SyncServerError {
             | Self::ClientError(error)
             | Self::ServerError(error)
             | Self::NotFound(error)
-            | Self::Unauthorized(error)
+            | Self::Unauthenticated(error)
             | Self::PermissionDeniedError(error) => error.into(),
         }
     }
@@ -53,7 +53,7 @@ impl IntoResponse for SyncServerError {
             }
             Self::ClientError(_) => (StatusCode::BAD_REQUEST, body).into_response(),
             Self::NotFound(_) => (StatusCode::NOT_FOUND, body).into_response(),
-            Self::Unauthorized(_) => (StatusCode::UNAUTHORIZED, body).into_response(),
+            Self::Unauthenticated(_) => (StatusCode::UNAUTHORIZED, body).into_response(),
             Self::PermissionDeniedError(_) => (StatusCode::FORBIDDEN, body).into_response(),
         }
     }
@@ -100,17 +100,16 @@ pub fn client_error(error: anyhow::Error) -> SyncServerError {
 }
 
 pub fn not_found_error(error: anyhow::Error) -> SyncServerError {
-    info!("Not found error: {:?}", error);
+    info!("Not found: {:?}", error);
     SyncServerError::NotFound(error)
 }
 
-pub fn unauthorized_error(error: anyhow::Error) -> SyncServerError {
-    info!("Unauthorized error: {:?}", error);
-    SyncServerError::Unauthorized(error)
+pub fn unauthenticated_error(error: anyhow::Error) -> SyncServerError {
+    info!("Unauthenticated user: {:?}", error);
+    SyncServerError::Unauthenticated(error)
 }
 
-#[allow(dead_code)]
 pub fn permission_denied_error(error: anyhow::Error) -> SyncServerError {
-    info!("Permission denied error: {:?}", error);
+    info!("Permission denied: {:?}", error);
     SyncServerError::PermissionDeniedError(error)
 }
diff --git a/backend/sync_server/src/server.rs b/backend/sync_server/src/server.rs
index 90bd8ff3..4bc85c0f 100644
--- a/backend/sync_server/src/server.rs
+++ b/backend/sync_server/src/server.rs
@@ -61,7 +61,7 @@ pub async fn create_server(config_path: Option<OsString>) -> Result<()> {
 
     let mut api = create_open_api();
     let app = ApiRouter::new()
-        .api_route("/ping", get(ping::ping))
+        .api_route("/vaults/:vault_id/ping", get(ping::ping))
         .api_route(
             "/vaults/:vault_id/documents",
             get(fetch_latest_documents::fetch_latest_documents),
diff --git a/backend/sync_server/src/server/auth.rs b/backend/sync_server/src/server/auth.rs
index ae20e187..06bfe5db 100644
--- a/backend/sync_server/src/server/auth.rs
+++ b/backend/sync_server/src/server/auth.rs
@@ -1,15 +1,26 @@
 use crate::{
-    app_state::AppState,
-    config::user_config::User,
-    errors::{SyncServerError, unauthorized_error},
+    app_state::{AppState, database::models::VaultId},
+    config::user_config::{AllowListedVaults, User, VaultAccess},
+    errors::{SyncServerError, permission_denied_error, unauthenticated_error},
 };
 
 // TODO: turn this into a middleware
-pub fn auth(app_state: &AppState, token: &str) -> Result<User, SyncServerError> {
-    app_state
+pub fn auth(app_state: &AppState, token: &str, vault: &VaultId) -> Result<User, SyncServerError> {
+    let user = app_state
         .config
         .users
         .get_user(token)
         .cloned()
-        .ok_or_else(|| unauthorized_error(anyhow::anyhow!("Invalid token")))
+        .ok_or_else(|| unauthenticated_error(anyhow::anyhow!("Invalid token")))?;
+
+    if match user.vault_access {
+        VaultAccess::AllowAccessToAll => true,
+        VaultAccess::AllowList(AllowListedVaults { ref allowed }) => allowed.contains(vault),
+    } {
+        Ok(user)
+    } else {
+        Err(permission_denied_error(anyhow::anyhow!(
+            "Permission denied for vault `{vault}`"
+        )))
+    }
 }
diff --git a/backend/sync_server/src/server/create_document.rs b/backend/sync_server/src/server/create_document.rs
index 826b37c6..25919384 100644
--- a/backend/sync_server/src/server/create_document.rs
+++ b/backend/sync_server/src/server/create_document.rs
@@ -87,7 +87,7 @@ async fn internal_create_document(
     relative_path: String,
     content: Vec<u8>,
 ) -> Result<Json<DocumentVersionWithoutContent>, SyncServerError> {
-    auth(&state, auth_header.token())?;
+    auth(&state, auth_header.token(), &vault_id)?;
 
     let mut transaction = state
         .database
diff --git a/backend/sync_server/src/server/delete_document.rs b/backend/sync_server/src/server/delete_document.rs
index 10fbca3c..82955676 100644
--- a/backend/sync_server/src/server/delete_document.rs
+++ b/backend/sync_server/src/server/delete_document.rs
@@ -37,7 +37,7 @@ pub async fn delete_document(
     State(state): State<AppState>,
     Json(request): Json<DeleteDocumentVersion>,
 ) -> Result<Json<DocumentVersionWithoutContent>, SyncServerError> {
-    auth(&state, auth_header.token())?;
+    auth(&state, auth_header.token(), &vault_id)?;
 
     let mut transaction = state
         .database
diff --git a/backend/sync_server/src/server/fetch_document_version.rs b/backend/sync_server/src/server/fetch_document_version.rs
index aab06c85..87900696 100644
--- a/backend/sync_server/src/server/fetch_document_version.rs
+++ b/backend/sync_server/src/server/fetch_document_version.rs
@@ -35,7 +35,7 @@ pub async fn fetch_document_version(
     }): Path<FetchDocumentVersionPathParams>,
     State(state): State<AppState>,
 ) -> Result<Json<DocumentVersion>, SyncServerError> {
-    auth(&state, auth_header.token())?;
+    auth(&state, auth_header.token(), &vault_id)?;
 
     let result = state
         .database
diff --git a/backend/sync_server/src/server/fetch_document_version_content.rs b/backend/sync_server/src/server/fetch_document_version_content.rs
index a2504ba1..24eddf40 100644
--- a/backend/sync_server/src/server/fetch_document_version_content.rs
+++ b/backend/sync_server/src/server/fetch_document_version_content.rs
@@ -37,7 +37,7 @@ pub async fn fetch_document_version_content(
     }): Path<FetchDocumentVersionContentPathParams>,
     State(state): State<AppState>,
 ) -> Result<Bytes, SyncServerError> {
-    auth(&state, auth_header.token())?;
+    auth(&state, auth_header.token(), &vault_id)?;
 
     let result = state
         .database
diff --git a/backend/sync_server/src/server/fetch_latest_document_version.rs b/backend/sync_server/src/server/fetch_latest_document_version.rs
index ec777f30..5ccfa4e9 100644
--- a/backend/sync_server/src/server/fetch_latest_document_version.rs
+++ b/backend/sync_server/src/server/fetch_latest_document_version.rs
@@ -33,7 +33,7 @@ pub async fn fetch_latest_document_version(
     }): Path<FetchLatestDocumentVersionPathParams>,
     State(state): State<AppState>,
 ) -> Result<Json<DocumentVersion>, SyncServerError> {
-    auth(&state, auth_header.token())?;
+    auth(&state, auth_header.token(), &vault_id)?;
 
     let latest_version = state
         .database
diff --git a/backend/sync_server/src/server/fetch_latest_documents.rs b/backend/sync_server/src/server/fetch_latest_documents.rs
index 2b4dc841..4b62a2f8 100644
--- a/backend/sync_server/src/server/fetch_latest_documents.rs
+++ b/backend/sync_server/src/server/fetch_latest_documents.rs
@@ -35,7 +35,7 @@ pub async fn fetch_latest_documents(
     Query(QueryParams { since_update_id }): Query<QueryParams>,
     State(state): State<AppState>,
 ) -> Result<Json<FetchLatestDocumentsResponse>, SyncServerError> {
-    auth(&state, auth_header.token())?;
+    auth(&state, auth_header.token(), &vault_id)?;
 
     let documents = if let Some(since_update_id) = since_update_id {
         state
diff --git a/backend/sync_server/src/server/ping.rs b/backend/sync_server/src/server/ping.rs
index 1fe75ee6..38dc2037 100644
--- a/backend/sync_server/src/server/ping.rs
+++ b/backend/sync_server/src/server/ping.rs
@@ -1,19 +1,34 @@
-use axum::{Json, extract::State};
+use axum::{
+    Json,
+    extract::{Path, State},
+};
 use axum_extra::{
     TypedHeader,
     headers::{Authorization, authorization::Bearer},
 };
+use schemars::JsonSchema;
+use serde::Deserialize;
 
 use super::{auth::auth, responses::PingResponse};
-use crate::{app_state::AppState, errors::SyncServerError};
+use crate::{
+    app_state::{AppState, database::models::VaultId},
+    errors::SyncServerError,
+};
+
+// This is required for aide to infer the path parameter types and names
+#[derive(Deserialize, JsonSchema)]
+pub struct PingPathParams {
+    vault_id: VaultId,
+}
 
 #[axum::debug_handler]
 pub async fn ping(
     maybe_auth_header: Option<TypedHeader<Authorization<Bearer>>>,
+    Path(PingPathParams { vault_id }): Path<PingPathParams>,
     State(state): State<AppState>,
 ) -> Result<Json<PingResponse>, SyncServerError> {
-    let is_authenticated =
-        maybe_auth_header.is_some_and(|auth_header| auth(&state, auth_header.token()).is_ok());
+    let is_authenticated = maybe_auth_header
+        .is_some_and(|auth_header| auth(&state, auth_header.token(), &vault_id).is_ok());
 
     Ok(Json(PingResponse {
         server_version: env!("CARGO_PKG_VERSION").to_owned(),
diff --git a/backend/sync_server/src/server/update_document.rs b/backend/sync_server/src/server/update_document.rs
index 0448ddb7..5bb39b70 100644
--- a/backend/sync_server/src/server/update_document.rs
+++ b/backend/sync_server/src/server/update_document.rs
@@ -92,7 +92,7 @@ async fn internal_update_document(
     relative_path: String,
     content: Vec<u8>,
 ) -> Result<Json<DocumentUpdateResponse>, SyncServerError> {
-    auth(&state, auth_header.token())?;
+    auth(&state, auth_header.token(), &vault_id)?;
 
     // No need for a transaction as document versions are immutable
     let parent_document = state
diff --git a/backend/sync_server/src/server/websocket.rs b/backend/sync_server/src/server/websocket.rs
index 30125f41..d672b944 100644
--- a/backend/sync_server/src/server/websocket.rs
+++ b/backend/sync_server/src/server/websocket.rs
@@ -20,7 +20,7 @@ use crate::{
         AppState,
         database::models::{DocumentVersionWithoutContent, VaultId, VaultUpdateId},
     },
-    errors::{SyncServerError, server_error, unauthorized_error},
+    errors::{SyncServerError, server_error, unauthenticated_error},
 };
 
 // This is required for aide to infer the path parameter types and names
@@ -73,9 +73,9 @@ async fn websocket(
     let (mut sender, mut receiver) = stream.split();
 
     if let Some(Ok(Message::Text(token))) = receiver.next().await {
-        auth(&state, &token)?;
+        auth(&state, &token, &vault_id)?;
     } else {
-        return Err(unauthorized_error(anyhow::anyhow!(
+        return Err(unauthenticated_error(anyhow::anyhow!(
             "Failed to authenticate"
         )));
     }