diff --git a/src/engine/mod.rs b/src/engine/mod.rs
index f5c531f..96af9bc 100644
--- a/src/engine/mod.rs
+++ b/src/engine/mod.rs
@@ -1,10 +1,16 @@
-mod analyzer;
+use std::sync::Arc;
+use std::time::Duration;
 
 use futures::{Future, Stream, stream};
 use hyper::Client;
 use hyper::client::HttpConnector;
 use hyper_tls::HttpsConnector;
 use slog::Logger;
+use tokio_service::Service;
+
+mod analyzer;
+
+use ::utils::throttle::{Throttle, ThrottledError};
 
 use ::models::repo::{Repository, RepoPath};
 use ::models::crates::{CrateName, CrateRelease, CrateManifest, AnalyzedDependencies};
@@ -13,17 +19,31 @@ use ::parsers::manifest::{ManifestParseError, parse_manifest_toml};
 
 use ::interactors::crates::{QueryCrateError, query_crate};
 use ::interactors::github::{RetrieveFileAtPathError, retrieve_file_at_path};
-use ::interactors::github::get_popular_repos;
-pub use ::interactors::github::GetPopularReposError;
+use ::interactors::github::GetPopularRepos;
 
 use self::analyzer::DependencyAnalyzer;
 
 #[derive(Clone, Debug)]
 pub struct Engine {
-    pub client: Client<HttpsConnector<HttpConnector>>,
-    pub logger: Logger
+    client: Client<HttpsConnector<HttpConnector>>,
+    logger: Logger,
+
+    get_popular_repos: Arc<Throttle<GetPopularRepos<Client<HttpsConnector<HttpConnector>>>>>
 }
 
+impl Engine {
+    pub fn new(client: Client<HttpsConnector<HttpConnector>>, logger: Logger) -> Engine {
+        Engine {
+            client: client.clone(), logger,
+
+            get_popular_repos: Arc::new(Throttle::new(GetPopularRepos(client), Duration::from_secs(10)))
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct GetPopularReposError(ThrottledError<::interactors::github::GetPopularReposError>);
+
 #[derive(Debug)]
 pub enum AnalyzeDependenciesError {
     QueryCrate(QueryCrateError),
@@ -42,7 +62,9 @@ impl Engine {
     pub fn get_popular_repos(&self) ->
         impl Future<Item=Vec<Repository>, Error=GetPopularReposError>
     {
-        get_popular_repos(self.client.clone())
+        self.get_popular_repos.call(())
+            .map_err(GetPopularReposError)
+            .map(|repos| repos.clone())
     }
 
     pub fn analyze_dependencies(&self, repo_path: RepoPath) ->
diff --git a/src/interactors/github.rs b/src/interactors/github.rs
index fdb4016..f22169f 100644
--- a/src/interactors/github.rs
+++ b/src/interactors/github.rs
@@ -74,33 +74,46 @@ struct GithubOwner {
     login: String
 }
 
-pub fn get_popular_repos<S>(service: S) ->
-    impl Future<Item=Vec<Repository>, Error=GetPopularReposError>
-    where S: Service<Request=Request, Response=Response, Error=HyperError>
+#[derive(Debug, Clone)]
+pub struct GetPopularRepos<S>(pub S);
+
+impl<S> Service for GetPopularRepos<S>
+    where S: Service<Request=Request, Response=Response, Error=HyperError> + Clone + 'static,
+          S::Future: 'static
 {
-    let uri_future = format!("{}/search/repositories?q=language:rust&sort=stars", GITHUB_API_BASE_URI)
-        .parse().into_future().map_err(GetPopularReposError::Uri);
+    type Request = ();
+    type Response = Vec<Repository>;
+    type Error = GetPopularReposError;
+    type Future = Box<Future<Item=Self::Response, Error=Self::Error>>;
 
-    uri_future.and_then(move |uri| {
-        let mut request = Request::new(Method::Get, uri);
-        request.headers_mut().set(UserAgent::new("deps.rs"));
+    fn call(&self, _req: ()) -> Self::Future {
+        println!("call api");
+        let service = self.0.clone();
 
-        service.call(request).map_err(GetPopularReposError::Transport).and_then(|response| {
-            let status = response.status();
-            if !status.is_success() {
-                future::Either::A(future::err(GetPopularReposError::Status(status)))
-            } else {
-                let body_future = response.body().concat2().map_err(GetPopularReposError::Transport);
-                let decode_future = body_future
-                    .and_then(|body| serde_json::from_slice(body.as_ref()).map_err(GetPopularReposError::Decode));
-                future::Either::B(decode_future.and_then(|search_response: GithubSearchResponse| {
-                    search_response.items.into_iter().map(|item| {
-                        let path = RepoPath::from_parts("github", &item.owner.login, &item.name)
-                            .map_err(GetPopularReposError::Validate)?;
-                        Ok(Repository { path, description: item.description })
-                    }).collect::<Result<Vec<_>, _>>()
-                }))
-            }
-        })
-    })
+        let uri_future = format!("{}/search/repositories?q=language:rust&sort=stars", GITHUB_API_BASE_URI)
+            .parse().into_future().map_err(GetPopularReposError::Uri);
+
+        Box::new(uri_future.and_then(move |uri| {
+            let mut request = Request::new(Method::Get, uri);
+            request.headers_mut().set(UserAgent::new("deps.rs"));
+
+            service.call(request).map_err(GetPopularReposError::Transport).and_then(|response| {
+                let status = response.status();
+                if !status.is_success() {
+                    future::Either::A(future::err(GetPopularReposError::Status(status)))
+                } else {
+                    let body_future = response.body().concat2().map_err(GetPopularReposError::Transport);
+                    let decode_future = body_future
+                        .and_then(|body| serde_json::from_slice(body.as_ref()).map_err(GetPopularReposError::Decode));
+                    future::Either::B(decode_future.and_then(|search_response: GithubSearchResponse| {
+                        search_response.items.into_iter().map(|item| {
+                            let path = RepoPath::from_parts("github", &item.owner.login, &item.name)
+                                .map_err(GetPopularReposError::Validate)?;
+                            Ok(Repository { path, description: item.description })
+                        }).collect::<Result<Vec<_>, _>>()
+                    }))
+                }
+            })
+        }))
+    }
 }
diff --git a/src/main.rs b/src/main.rs
index 156fadf..02d8377 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -20,6 +20,7 @@ extern crate tokio_core;
 extern crate tokio_service;
 extern crate toml;
 
+mod utils;
 mod models;
 mod parsers;
 mod interactors;
@@ -65,10 +66,7 @@ fn main() {
 
     let http = Http::new();
 
-    let engine = Engine {
-        client: client.clone(),
-        logger: logger.clone()
-    };
+    let engine = Engine::new(client.clone(), logger.clone());
 
     let server = Server::new(engine);
 
diff --git a/src/models/repo.rs b/src/models/repo.rs
index 3e29cc6..6f39bc5 100644
--- a/src/models/repo.rs
+++ b/src/models/repo.rs
@@ -1,12 +1,12 @@
 use std::str::FromStr;
 
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 pub struct Repository {
     pub path: RepoPath,
     pub description: String
 }
 
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 pub struct RepoPath {
     pub site: RepoSite,
     pub qual: RepoQualifier,
@@ -26,7 +26,7 @@ impl RepoPath {
 #[derive(Debug)]
 pub struct RepoValidationError;
 
-#[derive(Clone, Copy)]
+#[derive(Clone, Copy, Debug)]
 pub enum RepoSite {
     Github
 }
@@ -58,7 +58,7 @@ impl AsRef<str> for RepoSite {
     }
 }
 
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 pub struct RepoQualifier(String);
 
 impl FromStr for RepoQualifier {
@@ -83,7 +83,7 @@ impl AsRef<str> for RepoQualifier {
     }
 }
 
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 pub struct RepoName(String);
 
 impl FromStr for RepoName {
diff --git a/src/utils/mod.rs b/src/utils/mod.rs
new file mode 100644
index 0000000..dbec1e4
--- /dev/null
+++ b/src/utils/mod.rs
@@ -0,0 +1 @@
+pub mod throttle;
diff --git a/src/utils/throttle.rs b/src/utils/throttle.rs
new file mode 100644
index 0000000..5f3b620
--- /dev/null
+++ b/src/utils/throttle.rs
@@ -0,0 +1,123 @@
+use std::error::Error;
+use std::fmt::{Debug, Display, Formatter, Result as FmtResult};
+use std::time::{Duration, Instant};
+use std::ops::Deref;
+use std::sync::Mutex;
+
+use futures::{Future, Poll};
+use futures::future::{Shared, SharedError, SharedItem};
+use tokio_service::Service;
+
+pub struct Throttle<S: Service<Request=()>> {
+    inner: S,
+    duration: Duration,
+    current: Mutex<Option<(Instant, Shared<S::Future>)>>
+}
+
+impl<S> Debug for Throttle<S>
+    where S: Service<Request=()> + Debug,
+{
+    fn fmt(&self, fmt: &mut Formatter) -> FmtResult {
+        fmt.debug_struct("Throttle")
+            .field("inner", &self.inner)
+            .field("duration", &self.duration)
+            .finish()
+    }
+}
+
+impl<S: Service<Request=()>> Throttle<S> {
+    pub fn new(service: S, duration: Duration) -> Throttle<S> {
+        Throttle {
+            inner: service,
+            duration,
+            current: Mutex::new(None)
+        }
+    }
+}
+
+impl<S: Service<Request=()>> Service for Throttle<S> {
+    type Request = ();
+    type Response = ThrottledItem<S::Response>;
+    type Error = ThrottledError<S::Error>;
+    type Future = Throttled<S::Future>;
+
+    fn call(&self, _: ()) -> Self::Future {
+        let now = Instant::now();
+        let mut current = self.current.lock().expect("lock poisoned");
+        if let Some((valid_until, ref shared_future)) = *current {
+            if valid_until > now {
+                if let Some(Ok(_)) = shared_future.peek() {
+                    return Throttled(shared_future.clone());
+                }
+            }
+        }
+        let shared_future = self.inner.call(()).shared();
+        *current = Some((now + self.duration, shared_future.clone()));
+        Throttled(shared_future)
+    }
+}
+
+pub struct Throttled<F: Future>(Shared<F>);
+
+impl<F> Debug for Throttled<F>
+    where F: Future + Debug,
+          F::Item: Debug,
+          F::Error: Debug
+{
+    fn fmt(&self, fmt: &mut Formatter) -> FmtResult {
+        self.0.fmt(fmt)
+    }
+}
+
+impl<F: Future> Future for Throttled<F> {
+    type Item = ThrottledItem<F::Item>;
+    type Error = ThrottledError<F::Error>;
+
+    fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
+        self.0.poll()
+            .map_err(ThrottledError)
+            .map(|async| async.map(ThrottledItem))
+    }
+}
+
+#[derive(Debug)]
+pub struct ThrottledItem<T>(SharedItem<T>);
+
+impl<T> Deref for ThrottledItem<T> {
+    type Target = T;
+
+    fn deref(&self) -> &T {
+        &self.0.deref()
+    }
+}
+
+#[derive(Debug)]
+pub struct ThrottledError<E>(SharedError<E>);
+
+impl<E> Deref for ThrottledError<E> {
+    type Target = E;
+
+    fn deref(&self) -> &E {
+        &self.0.deref()
+    }
+}
+
+impl<E> Display for ThrottledError<E>
+    where E: Display,
+{
+    fn fmt(&self, f: &mut Formatter) -> FmtResult {
+        self.0.fmt(f)
+    }
+}
+
+impl<E> Error for ThrottledError<E>
+    where E: Error,
+{
+    fn description(&self) -> &str {
+        self.0.description()
+    }
+
+    fn cause(&self) -> Option<&Error> {
+        self.0.cause()
+    }
+}