diff --git a/src/IndexJSON.jl b/src/IndexJSON.jl
index 1694f5a..0dd9e8b 100644
--- a/src/IndexJSON.jl
+++ b/src/IndexJSON.jl
@@ -60,6 +60,13 @@ function json_data(
         #     c === nothing ? nothing : [
         #     v for (k,v) in sort(pairs(c); by=((k,v)) -> parse(Int, k))
         # ],
+        binder_url=settings.Export.offer_binder ?
+                   something(settings.Export.binder_url, Pluto.default_binder_url) :
+                   nothing,
+        slider_server_url=somethingornothing(
+            settings.Export.slider_server_url,
+            settings.SliderServer.enabled ? "." : nothing,
+        ),
     )
 end
 
@@ -76,4 +83,8 @@ function generate_index_json(
     end
     result = json_data(sessions; settings, start_dir, config_data)
     JSON.json(result)
-end
\ No newline at end of file
+end
+
+somethingornothing() = nothing
+somethingornothing(x::Nothing, y...) = somethingornothing(y...)
+somethingornothing(x::Any, y...) = x
diff --git a/test/static export.jl b/test/static export.jl
index 8dc5c4d..94f279c 100644
--- a/test/static export.jl	
+++ b/test/static export.jl	
@@ -57,6 +57,10 @@ make_test_dir() =
     @test second_runtime < 1.0
 
     @test occursin("slider_server_url = undefined", read("a.html", String))
+
+    jsonstr = read("pluto_export.json", String)
+    json = JSON.parse(jsonstr)
+    @test json["slider_server_url"] === nothing
 end
 
 
@@ -167,6 +171,7 @@ end
         Export_cache_dir=cache_dir,
         Export_baked_state=false,
         Export_create_pluto_featured_index=fancy,
+        Export_slider_server_url="krat",
     )
 
     @test sort(list_files_recursive()) == sort([
@@ -193,6 +198,7 @@ end
         @test occursin("</html>", htmlstr)
         @test occursin("pluto_export.json", htmlstr)
     end
+    @test json["slider_server_url"] == "krat"
 
     nbs = ["subdir/c.plutojl", "b.pluto.jl", "a.jl"]
     for (i, p) in enumerate(nbs)