diff --git a/lib/gemstash/gem_source/private_source.rb b/lib/gemstash/gem_source/private_source.rb
index 025312d0..5195570d 100644
--- a/lib/gemstash/gem_source/private_source.rb
+++ b/lib/gemstash/gem_source/private_source.rb
@@ -50,6 +50,17 @@ def serve_versions
         halt 404, "Not yet supported"
       end
 
+      def serve_gem_versions(name)
+        authorization.protect(self) do
+          auth.check("fetch") if gemstash_env.config[:protected_fetch]
+          name.slice! ".json"
+          gem = fetch_gem(name)
+          halt 404 unless gem.exist?(:spec)
+          content_type "application/json;charset=UTF-8"
+          fetch_gem_versions(name).to_json
+        end
+      end
+
       def serve_info(name)
         halt 403, "Not yet supported"
       end
@@ -118,6 +129,29 @@ def fetch_gem(gem_full_name)
         halt 403, "That gem has been yanked" unless gem.properties[:indexed]
         gem
       end
+
+      def fetch_gem_versions(gem)
+        results = db["
+          SELECT rubygem.name,
+                 version.number, version.platform
+          FROM rubygems rubygem
+          JOIN versions version
+            ON version.rubygem_id = rubygem.id
+          WHERE rubygem.name = ?
+            AND version.indexed = ?", gem.to_a, true].to_a
+        results.group_by {|r| r[:name] }.each do |rows|
+          requirements = rows.group_by {|r| [r[:number], r[:platform]] }
+
+          value = requirements.map do |(version, platform)|
+            {
+              :number => version,
+              :platform => platform
+            }
+          end
+
+          yield(gem, value)
+        end
+      end
     end
   end
 end
diff --git a/lib/gemstash/gem_source/upstream_source.rb b/lib/gemstash/gem_source/upstream_source.rb
index 48f17c9a..7a53f52a 100644
--- a/lib/gemstash/gem_source/upstream_source.rb
+++ b/lib/gemstash/gem_source/upstream_source.rb
@@ -62,6 +62,10 @@ def serve_versions
         redirect index_upstream.url("versions", request.query_string)
       end
 
+      def serve_gem_versions(name)
+        redirect index_upstream.url("api/v1/versions/#{name}", request.query_string)
+      end
+
       def serve_info(name)
         redirect index_upstream.url("info/#{name}", request.query_string)
       end
diff --git a/lib/gemstash/web.rb b/lib/gemstash/web.rb
index ae2428c8..675d2c9c 100644
--- a/lib/gemstash/web.rb
+++ b/lib/gemstash/web.rb
@@ -47,6 +47,10 @@ def http_client_for(server_url)
       @gem_source.serve_dependencies_json
     end
 
+    get "/api/v1/versions/:name" do
+      @gem_source.serve_gem_versions(params[:name])
+    end
+
     post "/api/v1/gems" do
       @gem_source.serve_add_gem
     end
diff --git a/spec/gemstash/web_spec.rb b/spec/gemstash/web_spec.rb
index 26892975..2af0021f 100644
--- a/spec/gemstash/web_spec.rb
+++ b/spec/gemstash/web_spec.rb
@@ -201,6 +201,63 @@ def for(server_url, timeout = 20)
     end
   end
 
+  context "GET /api/v1/versions/:name" do
+    context "from the default upstream" do
+      let(:current_env) { Gemstash::Env.current }
+      let(:upstream) { Gemstash::Upstream.new(current_env.config[:rubygems_url]) }
+      let(:storage) { Gemstash::LocalStorage.for("gem_cache").for(upstream.host_id) }
+
+      it "fetches the gem informations as json" do
+        result = [{
+          "number" => "1.0.0",
+          "platform" => "ruby"
+        }]
+
+        get "/api/v1/versions/rack.json", {}, rack_env
+        expect(last_response).to be_ok
+        expect(JSON.parse(last_response.body)).to eq(result)
+      end
+
+      it "can be called multiple times without error" do
+        get "/api/v1/versions/rack.json", {}, rack_env
+        get "/api/v1/versions/rack.json", {}, rack_env
+      end
+    end
+
+    context "from private gems" do
+      let(:gem_source) { Gemstash::GemSource::PrivateSource }
+      let(:storage) { Gemstash::LocalStorage.for("private").for("gems") }
+
+      context "with a missing gem" do
+        it "halts with 404" do
+          get "/api/v1/versions/unknown.json", {}, rack_env
+          expect(last_response).to_not be_ok
+          expect(last_response.status).to eq(404)
+          expect(last_response.body).to match(/not found/i)
+        end
+      end
+
+      context "with a regular gem" do
+        before do
+          gem_id = insert_rubygem "example"
+          insert_version gem_id, "0.1.0"
+          storage.resource("example-0.1.0").save({ gem: "Example gem content" }, indexed: true)
+        end
+
+        it "fetches the gem informations as json" do
+          result = [{
+            "number" => "0.1.0",
+            "platform" => "ruby"
+          }]
+
+          get "/api/v1/versions/example.json", {}, rack_env
+          expect(last_response).to be_ok
+          expect(JSON.parse(last_response.body)).to eq(result)
+        end
+      end
+    end
+  end
+
   context "GET /gems/:id" do
     context "from the default upstream" do
       let(:current_env) { Gemstash::Env.current }