diff --git a/lib/Cargo.toml b/lib/Cargo.toml
index 18c5695..99622ce 100644
--- a/lib/Cargo.toml
+++ b/lib/Cargo.toml
@@ -24,6 +24,7 @@ async-trait = "0.1.81"
 dirs = "5.0.1"
 libloading = "0.8.5"
 base64 = "0.22.1"
+sha2 = "0.10.8"
 
 [dependencies.reqwest]
 version = "^0.11"
diff --git a/lib/src/utils/extension.rs b/lib/src/utils/extension.rs
index 701d3da..f8a893c 100644
--- a/lib/src/utils/extension.rs
+++ b/lib/src/utils/extension.rs
@@ -49,6 +49,8 @@ pub struct Extension {
     pub version: String,
     /// The file path to the extension.
     pub path: String,
+    /// SHA512 checksum of the extension binary.
+    pub checksum: String,
     /// An optional description of the extension.
     pub description: Option<String>,
 }
diff --git a/lib/src/utils/extension_manager.rs b/lib/src/utils/extension_manager.rs
index afdfcb8..422dbbb 100644
--- a/lib/src/utils/extension_manager.rs
+++ b/lib/src/utils/extension_manager.rs
@@ -42,6 +42,8 @@ use crate::utils::expand_path_with_home_dir;
 use std::io::Read;
 use serde_json::Value;
 use std::collections::HashMap;
+use sha2::{Sha512, Digest};
+use std::fs::File;
 
 type InstalledExtensions = Vec<InstalledExtension>;
 
@@ -173,7 +175,7 @@ impl ExtensionManager {
         if extensions_json.extensions.iter().any(|ext| ext.name == extension.name) {
             warn!("Extension '{}' already exists in the configuration.", extension.name);
             return Ok(());
-        }
+        } 
 
         let extension_lib_filename = crate::utils::extract_filename_from_url(extension.path.as_str()).unwrap();
         let extension_folder_path = expand_path_with_home_dir(format!(".ga4gh/extensions/{}/", extension.name).as_str());
@@ -186,6 +188,20 @@ impl ExtensionManager {
         debug!("Downloading extension library from {} to {}", extension.path.as_str(), local_extension_lib_path);
         crate::utils::download_file(&extension.path, local_extension_lib_path.as_str()).await;
 
+        // Calculate the checksum of the downloaded file
+        let mut file = File::open(&local_extension_lib_path)?;
+        let mut hasher = Sha512::new();
+        let mut buffer = Vec::new();
+        file.read_to_end(&mut buffer)?;
+        hasher.update(&buffer);
+        let calculated_checksum = format!("{:x}", hasher.finalize());
+
+        if calculated_checksum != extension.checksum {
+            error!("Checksum mismatch for extension '{}'.\nExpected:   {}\nCalculated: {}", extension.name, extension.checksum, calculated_checksum);
+            std::fs::remove_dir_all(&extension_folder_path)?;
+            return Err(Box::new(std::io::Error::new(std::io::ErrorKind::InvalidData, "Checksum mismatch")));
+        }
+
         let installed_definition_file_path = expand_path_with_home_dir(format!(".ga4gh/extensions/{}/{}.ga4gh-sdk-extension.json", extension.name, extension.name).as_str());
         let full_definition_file_path = fs::canonicalize(&installed_definition_file_path)?.to_str().unwrap().to_string();
         let new_extension_record = InstalledExtension {