diff --git a/src/server-defaults.jl b/src/server-defaults.jl
index c19f42f1..90a74faa 100644
--- a/src/server-defaults.jl
+++ b/src/server-defaults.jl
@@ -178,16 +178,19 @@ end
 
 get_server() = get_server(find_proxy_in_environment())
 
-function get_server(proxy_callback)
-    # we have found nothing, so don't do any fancy setup
-    if isnothing(proxy_callback)
-        return singleton_server()
-    else
-        url = proxy_callback(8888) # call it with any port, to see if its empty and therefore no proxy is found/needed
-        listen_url = isempty(url) ? "127.0.0.1" : "0.0.0.0" # we only need to serve on 0.0.0.0, if we proxy
-        server = singleton_server(; listen_url=listen_url)
-        real_port = server.port # can change if already in use
-        server.proxy_url = proxy_callback(real_port) # which is why the url needs to be a callbacks
-        return server
-    end
+# we have found nothing, so don't do any fancy setup
+get_server(::Nothing) = singleton_server()
+
+function get_server(proxy_callback::Function)
+    url = proxy_callback(8888) # call it with any port, to see if its empty and therefore no proxy is found/needed
+    listen_url = isempty(url) ? "127.0.0.1" : "0.0.0.0" # we only need to serve on 0.0.0.0, if we proxy
+    server = singleton_server(; listen_url=listen_url)
+    real_port = server.port # can change if already in use
+    server.proxy_url = proxy_callback(real_port) # which is why the url needs to be a callbacks
+    return server
 end
+
+get_server(session::Session) = get_server(session.asset_server)
+get_server(server::HTTPAssetServer) = server.server
+get_server(server::Bonito.ChildAssetServer) = get_server(server.parent)
+get_server(any) = error("Not an HTTP server for session")
diff --git a/test/server.jl b/test/server.jl
index 554b1f58..50e07355 100644
--- a/test/server.jl
+++ b/test/server.jl
@@ -38,3 +38,10 @@ using RelocatableFolders
     @test isfile(Bonito.serving_target(asset))
     @test read(Bonito.serving_target(asset)) isa Vector{UInt8}
 end
+
+@testset "get online URL" begin
+    App() do session::Session
+        server = get_server(session)
+        DOM.div(string(Bonito.online_url(server, "")))
+    end
+end