diff --git a/Cargo.toml b/Cargo.toml
index 757a43a..1bf7e31 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -13,7 +13,7 @@ anyhow = "1.0"
 serde = { version = "1.0.188", features = ["derive"] }
 serde_json = "1.0.107"
 bitcoin = { version = "0.31.1", features = ["serde", "rand", "base64"] }
-rayon = "1.10.0"
+rayon = { version = "1.10.0", optional = true }
 futures = "0.3"
 log = "0.4"
 async-trait = "0.1"
@@ -22,4 +22,5 @@ hex = { version = "0.4.3", features = ["serde"], optional = true }
 bdk_coin_select = "0.4.0"
 
 [features]
+default = ["blindbit-backend", "rayon"]
 blindbit-backend = ["reqwest", "hex"]
diff --git a/src/client/client.rs b/src/client/client.rs
index 0a4c1d0..0772d60 100644
--- a/src/client/client.rs
+++ b/src/client/client.rs
@@ -108,17 +108,23 @@ impl SpClient {
         &self,
         tweak_data_vec: Vec<PublicKey>,
     ) -> Result<HashMap<[u8; 34], PublicKey>> {
+        // if using rayon feature, import the preludes
+        #[cfg(feature = "rayon")]
         use rayon::prelude::*;
+
         let b_scan = &self.get_scan_key();
 
-        let shared_secrets: Vec<PublicKey> = tweak_data_vec
-            .into_par_iter()
-            .map(|tweak| sp_utils::receiving::calculate_ecdh_shared_secret(&tweak, b_scan))
-            .collect();
+        // parallel iterator using rayon
+        #[cfg(feature = "rayon")]
+        let tweak_data_iterator = tweak_data_vec.into_par_iter();
+
+        // regular iterator
+        #[cfg(not(feature = "rayon"))]
+        let tweak_data_iterator = tweak_data_vec.into_iter();
 
-        let items: Result<Vec<_>> = shared_secrets
-            .into_par_iter()
-            .map(|secret| {
+        let items: Result<Vec<_>> = tweak_data_iterator
+            .map(|tweak| {
+                let secret = sp_utils::receiving::calculate_ecdh_shared_secret(&tweak, b_scan);
                 let spks = self.sp_receiver.get_spks_from_shared_secret(&secret)?;
 
                 Ok((secret, spks.into_values()))