diff --git a/apps/transport/lib/jobs/gtfs_diff_job.ex b/apps/transport/lib/jobs/gtfs_diff_job.ex
index 3588c60362..533b7ea340 100644
--- a/apps/transport/lib/jobs/gtfs_diff_job.ex
+++ b/apps/transport/lib/jobs/gtfs_diff_job.ex
@@ -5,27 +5,89 @@ defmodule Transport.Jobs.GTFSDiff do
   use Oban.Worker, max_attempts: 1, queue: :on_demand_validation
 
   @impl Oban.Worker
-  def perform(
-        %Oban.Job{
-          args: %{
-            "gtfs_file_name_1" => gtfs_file_name_1,
-            "gtfs_file_name_2" => gtfs_file_name_2,
-            "gtfs_original_file_name_1" => gtfs_original_file_name_1,
-            "gtfs_original_file_name_2" => gtfs_original_file_name_2,
-            "bucket" => bucket,
-            "locale" => locale,
-            "profile" => profile
-          }
-        } = job
-      ) do
+  def perform(%Oban.Job{args: args} = job) do
     Oban.Notifier.notify(Oban, :gossip, %{started: job.id})
 
-    {:ok, unzip_1} = Transport.Unzip.S3.get_unzip(gtfs_file_name_1, bucket)
-    {:ok, unzip_2} = Transport.Unzip.S3.get_unzip(gtfs_file_name_2, bucket)
+    case args do
+      %{"gtfs_object_1" => gtfs_object_1, "gtfs_object_2" => gtfs_object_2} ->
+        process_s3_objects(job.id, gtfs_object_1, gtfs_object_2, args)
 
+      %{"gtfs_url_1" => gtfs_url_1, "gtfs_url_2" => gtfs_url_2} ->
+        process_urls(job.id, gtfs_url_1, gtfs_url_2, args)
+    end
+
+    :ok
+  end
+
+  @impl Oban.Worker
+  def timeout(_job), do: :timer.seconds(job_timeout_sec())
+
+  # 30 minutes, in seconds
+  def job_timeout_sec, do: 30 * 60
+
+  defp process_s3_objects(job_id, gtfs_object_1, gtfs_object_2, args) do
+    bucket_name = Transport.S3.bucket_name(:gtfs_diff)
+
+    {:ok, unzip_1} = Transport.Unzip.S3.get_unzip(gtfs_object_1, bucket_name)
+    {:ok, unzip_2} = Transport.Unzip.S3.get_unzip(gtfs_object_2, bucket_name)
+
+    process_diff(job_id, unzip_1, unzip_2, args)
+  after
+    Transport.S3.delete_object!(:gtfs_diff, gtfs_object_1)
+    Transport.S3.delete_object!(:gtfs_diff, gtfs_object_2)
+  end
+
+  defp process_urls(job_id, gtfs_url_1, gtfs_url_2, args) do
+    {:ok, file_1} = download_resource(gtfs_url_1)
+    {:ok, file_2} = download_resource(gtfs_url_2)
+
+    try do
+      {:ok, unzip_1} = unzip_local(file_1)
+      {:ok, unzip_2} = unzip_local(file_2)
+
+      process_diff(job_id, unzip_1, unzip_2, args)
+    after
+      File.rm(file_1)
+      File.rm(file_2)
+    end
+  end
+
+  defp download_resource(url) do
+    file_path = mk_tmp_file()
+    file_stream = File.stream!(file_path)
+
+    req_options = [compressed: false, decode_body: false, receive_timeout: 180_000, into: file_stream]
+
+    case Transport.Req.impl().get(url, req_options) do
+      {:ok, %{status: 200}} ->
+        {:ok, file_path}
+
+      {:ok, %{status: status_code}} ->
+        # NOTE: the file is still on disk at this point
+        {:error, "Got a non 200 status: #{status_code}"}
+
+      {:error, error} ->
+        {:error, "Got an error: #{error |> inspect}"}
+    end
+  end
+
+  defp mk_tmp_file do
+    System.tmp_dir!() |> Path.join(Ecto.UUID.generate())
+  end
+
+  defp unzip_local(file) do
+    file |> Unzip.LocalFile.open() |> Unzip.new()
+  end
+
+  defp process_diff(job_id, unzip_1, unzip_2, %{
+         "gtfs_original_file_name_1" => gtfs_original_file_name_1,
+         "gtfs_original_file_name_2" => gtfs_original_file_name_2,
+         "profile" => profile,
+         "locale" => locale
+       }) do
     notify = fn log_msg ->
       Oban.Notifier.notify(Oban, :gossip, %{
-        running: job.id,
+        running: job_id,
         log: log_msg
       })
     end
@@ -40,7 +102,7 @@ defmodule Transport.Jobs.GTFSDiff do
       Transport.S3.stream_to_s3!(:gtfs_diff, filepath, diff_file_name, acl: :public_read)
 
       Oban.Notifier.notify(Oban, :gossip, %{
-        complete: job.id,
+        complete: job_id,
         diff_file_url: Transport.S3.permanent_url(:gtfs_diff, diff_file_name),
         gtfs_original_file_name_1: gtfs_original_file_name_1,
         gtfs_original_file_name_2: gtfs_original_file_name_2
@@ -48,15 +110,5 @@ defmodule Transport.Jobs.GTFSDiff do
     after
       File.rm(filepath)
     end
-
-    Transport.S3.delete_object!(:gtfs_diff, gtfs_file_name_1)
-    Transport.S3.delete_object!(:gtfs_diff, gtfs_file_name_2)
-    :ok
   end
-
-  @impl Oban.Worker
-  def timeout(_job), do: :timer.seconds(job_timeout_sec())
-
-  # 30 minutes, in seconds
-  def job_timeout_sec, do: 30 * 60
 end
diff --git a/apps/transport/lib/transport_web/live/gtfs_diff_select_live.ex b/apps/transport/lib/transport_web/live/gtfs_diff_select_live.ex
index b953a455cc..59977e13fa 100644
--- a/apps/transport/lib/transport_web/live/gtfs_diff_select_live.ex
+++ b/apps/transport/lib/transport_web/live/gtfs_diff_select_live.ex
@@ -14,17 +14,37 @@ defmodule TransportWeb.Live.GTFSDiffSelectLive do
   import TransportWeb.Live.GTFSDiffSelectLive.Shared
   import TransportWeb.Live.GTFSDiffSelectLive.Steps
 
-  def mount(_params, %{"locale" => locale} = _session, socket) do
+  def mount(params, %{"locale" => locale} = _session, socket) do
     Gettext.put_locale(locale)
 
-    {:ok,
-     socket
-     |> clean_slate()
-     |> setup_uploads()}
+    socket = clean_slate(socket)
+
+    case params do
+      :not_mounted_at_router -> {:ok, setup_uploads(socket)}
+      %{} -> {:ok, setup_uploads(socket)}
+      _ -> {:ok, do_handle_params(socket, params)}
+    end
   end
 
   def handle_params(params, _uri, socket) do
-    {:noreply, set_profile(socket, params)}
+    {:noreply, do_handle_params(socket, params)}
+  end
+
+  defp do_handle_params(socket, params) do
+    socket |> set_profile(params) |> handle_urls(params)
+  end
+
+  defp handle_urls(socket, %{"reference_url" => reference_url, "modified_url" => modified_url}) do
+    profile = socket.assigns[:profile]
+
+    socket
+    |> assign(current_step: :analysis)
+    |> trigger_job(reference_url, modified_url, profile)
+    |> scroll_to_steps()
+  end
+
+  defp handle_urls(socket, _) do
+    setup_uploads(socket)
   end
 
   def set_profile(socket, %{"profile" => profile}) do
@@ -71,18 +91,9 @@ defmodule TransportWeb.Live.GTFSDiffSelectLive do
   end
 
   def handle_info(:enqueue_job, socket) do
-    [gtfs_file_name_2, gtfs_file_name_1] = read_uploaded_files(socket)
-
-    :ok = listen_job_notifications()
-
-    job_id = schedule_job(gtfs_file_name_1, gtfs_file_name_2, socket.assigns[:profile])
-
-    socket =
-      socket
-      |> assign(job_id: job_id)
-      |> assign(diff_logs: [dgettext("gtfs-diff", "Job started")])
+    [gtfs_file_2, gtfs_file_1] = read_uploaded_files(socket)
 
-    {:noreply, socket}
+    {:noreply, socket |> trigger_job(gtfs_file_1, gtfs_file_2, socket.assigns[:profile])}
   end
 
   def handle_info({:generate_diff_summary, diff_file_url}, socket) do
@@ -113,6 +124,16 @@ defmodule TransportWeb.Live.GTFSDiffSelectLive do
     {:noreply, socket}
   end
 
+  defp trigger_job(socket, gtfs_file_1, gtfs_file_2, profile) do
+    :ok = listen_job_notifications()
+
+    job_id = schedule_job(gtfs_file_1, gtfs_file_2, profile)
+
+    socket
+    |> assign(job_id: job_id)
+    |> assign(diff_logs: [dgettext("gtfs-diff", "Job started")])
+  end
+
   # job has started
   def handle_job_notification(%{"started" => job_id}, job_id, socket) do
     schedule_timeout()
@@ -143,6 +164,8 @@ defmodule TransportWeb.Live.GTFSDiffSelectLive do
     |> scroll_to_steps()
   end
 
+  def handle_job_notification(_, _, socket), do: socket
+
   defp read_uploaded_files(socket) do
     consume_uploaded_entries(socket, :gtfs, &consume_uploaded_entry/2)
   end
@@ -153,17 +176,44 @@ defmodule TransportWeb.Live.GTFSDiffSelectLive do
     {:ok, %{uploaded_file_name: file_name, original_file_name: original_file_name}}
   end
 
-  defp schedule_job(gtfs_file_name_1, gtfs_file_name_2, profile) do
-    %{id: job_id} =
+  defp schedule_job(gtfs_url_1, gtfs_url_2, profile) when is_binary(gtfs_url_1) do
+    schedule_job(
       %{
-        gtfs_file_name_1: gtfs_file_name_1.uploaded_file_name,
-        gtfs_file_name_2: gtfs_file_name_2.uploaded_file_name,
-        gtfs_original_file_name_1: gtfs_file_name_1.original_file_name,
-        gtfs_original_file_name_2: gtfs_file_name_2.original_file_name,
-        bucket: Transport.S3.bucket_name(:gtfs_diff),
+        gtfs_url_1: gtfs_url_1,
+        gtfs_url_2: gtfs_url_2,
+        gtfs_original_file_name_1: "reference.zip",
+        gtfs_original_file_name_2: "modified.zip"
+      },
+      profile
+    )
+  end
+
+  defp schedule_job(
+         %{uploaded_file_name: gtfs_object_1, original_file_name: gtfs_original_file_name_1},
+         %{
+           uploaded_file_name: gtfs_object_2,
+           original_file_name: gtfs_original_file_name_2
+         },
+         profile
+       ) do
+    schedule_job(
+      %{
+        gtfs_object_1: gtfs_object_1,
+        gtfs_object_2: gtfs_object_2,
+        gtfs_original_file_name_1: gtfs_original_file_name_1,
+        gtfs_original_file_name_2: gtfs_original_file_name_2
+      },
+      profile
+    )
+  end
+
+  defp schedule_job(args, profile) do
+    %{id: job_id} =
+      args
+      |> Map.merge(%{
         locale: Gettext.get_locale(),
         profile: profile
-      }
+      })
       |> Transport.Jobs.GTFSDiff.new()
       |> Oban.insert!()