diff --git a/sample.conf b/sample.conf
index 96d11dd..6678722 100644
--- a/sample.conf
+++ b/sample.conf
@@ -9,7 +9,9 @@ mirrors = [
 
 # Local cache directory
 cache_dir = "./data"
-#ttl = "3h"
+
+# Time in minutes before a file is counted as out of date
+ttl = "180"
 
 # Regex for paths which will never be served from cache
 no_cache = '.*(?:db|db\.sig)$'
\ No newline at end of file
diff --git a/src/config.rs b/src/config.rs
index f11a43c..f50582e 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -7,10 +7,16 @@ pub struct Config {
     pub mirrors: Vec<String>,
     pub cache_dir: String,
     pub no_cache: String,
+    pub ttl: usize,
 }
 
 impl Config {
     pub fn to_proxy(&self) -> Mirror {
-        Mirror::new(self.mirrors.clone(), &self.cache_dir, &self.no_cache)
+        Mirror::new(
+            self.mirrors.clone(),
+            &self.cache_dir,
+            &self.no_cache,
+            self.ttl,
+        )
     }
 }
diff --git a/src/proxy.rs b/src/proxy.rs
index 8fc4d16..656ed36 100644
--- a/src/proxy.rs
+++ b/src/proxy.rs
@@ -8,15 +8,17 @@ use std::{
 pub struct Mirror {
     mirrors: Vec<Arc<String>>,
     data_dir: String,
+    ttl: usize,
     no_cache: regex::Regex,
 }
 
 impl Mirror {
-    pub fn new(mirrors: Vec<String>, data_dir: &str, no_cache: &str) -> Self {
+    pub fn new(mirrors: Vec<String>, data_dir: &str, no_cache: &str, ttl: usize) -> Self {
         Self {
             mirrors: mirrors.into_iter().map(Arc::new).collect(),
             data_dir: data_dir.to_string(),
             no_cache: regex::Regex::new(no_cache).unwrap(),
+            ttl,
         }
     }
 
@@ -49,6 +51,29 @@ impl Mirror {
         }
     }
 
+    pub fn is_cache_invalid(&self, p: &Path) -> bool {
+        let try_is_cache_invalid = || {
+            let modified = p.metadata().ok()?.modified().ok()?;
+            let current_time = std::time::SystemTime::now();
+            let elapsed_time = current_time.duration_since(modified).ok()?;
+            let threshold_duration =
+                std::time::Duration::from_secs((self.ttl * 60).try_into().unwrap());
+
+            if elapsed_time > threshold_duration {
+                log::info!(
+                    "Cached file is {} minutes old. Older than TTL {}.",
+                    (elapsed_time.as_secs() / 60),
+                    self.ttl
+                );
+                Some(true)
+            } else {
+                Some(false)
+            }
+        };
+
+        try_is_cache_invalid().unwrap_or(false)
+    }
+
     /// Asynchronously retrieves content from the specified path, either from cache or mirrors.
     ///
     /// This function attempts to retrieve content from the specified `path`. If caching is enabled
@@ -69,7 +94,7 @@ impl Mirror {
         let p = std::path::Path::new(&self.data_dir).join(p);
 
         // check if cache should be used
-        if !self.no_cache.is_match(path) {
+        if !self.no_cache.is_match(path) || !self.is_cache_invalid(&p) {
             Self::create_cache_dir(p.parent().unwrap());
 
             // use cache if present
@@ -90,7 +115,6 @@ impl Mirror {
 
     pub async fn fetch_cache(&self, p: &PathBuf, req: &HttpRequest) -> Option<HttpResponse> {
         if p.exists() {
-            // todo : refresh caches
             if p.is_dir() {
                 return Some(
                     actix_files::NamedFile::open_async(p.join("index"))