diff --git a/gitlab-pages/docs/reference/toplevel.md b/gitlab-pages/docs/reference/toplevel.md
new file mode 100644
index 000000000..c8b819a81
--- /dev/null
+++ b/gitlab-pages/docs/reference/toplevel.md
@@ -0,0 +1,86 @@
+---
+id: toplevel
+title: Toplevel
+description: Available functions at the top level
+hide_table_of_contents: true
+---
+
+import Syntax from '@theme/Syntax';
+import SyntaxTitle from '@theme/SyntaxTitle';
+
+These functions are available without any needed prefix.
+
+<SyntaxTitle syntax="pascaligo">
+function is_nat: int -> option(nat)
+</Syntax>
+<SyntaxTitle syntax="pascaligo">
+val is_nat: int -> nat option
+</Syntax>
+<SyntaxTitle syntax="pascaligo">
+let is_nat: int => option(nat)
+</Syntax>
+
+Convert an `int` to a `nat` if possible.
+
+<SyntaxTitle syntax="pascaligo">
+function abs: int -> nat
+</Syntax>
+<SyntaxTitle syntax="pascaligo">
+val abs: int -> nat
+</Syntax>
+<SyntaxTitle syntax="pascaligo">
+let abs: int => nat
+</Syntax>
+
+Cast an `int` to `nat`.
+
+<SyntaxTitle syntax="pascaligo">
+function int: nat -> int
+</Syntax>
+<SyntaxTitle syntax="pascaligo">
+val int: nat -> int
+</Syntax>
+<SyntaxTitle syntax="pascaligo">
+let int: nat => int
+</Syntax>
+
+Cast an `nat` to `int`.
+
+<SyntaxTitle syntax="pascaligo">
+const unit: unit
+</Syntax>
+<SyntaxTitle syntax="pascaligo">
+val unit: unit
+</Syntax>
+<SyntaxTitle syntax="pascaligo">
+let (): unit
+</Syntax>
+
+A helper to create a unit.
+
+<SyntaxTitle syntax="pascaligo">
+function failwith : string -> unit
+</SyntaxTitle>
+<SyntaxTitle syntax="cameligo">
+function failwith : string -> unit
+</SyntaxTitle>
+<SyntaxTitle syntax="reasonligo">
+function failwith : string -> unit
+</SyntaxTitle>
+
+Cause the contract to fail with an error message.
+
+> ⚠ Using this currently requires in general a type annotation on the
+> `failwith` call.
+
+<SyntaxTitle syntax="pascaligo">
+function assert : bool -> unit
+</SyntaxTitle>
+<SyntaxTitle syntax="cameligo">
+function assert : bool -> unit
+</SyntaxTitle>
+<SyntaxTitle syntax="reasonligo">
+function assert : bool -> unit
+</SyntaxTitle>
+
+Check if a certain condition has been met. If not the contract will fail.
diff --git a/gitlab-pages/website/sidebars.json b/gitlab-pages/website/sidebars.json
index 9359599ec..2d32e898b 100644
--- a/gitlab-pages/website/sidebars.json
+++ b/gitlab-pages/website/sidebars.json
@@ -27,6 +27,7 @@
       "api/cheat-sheet"
     ],
     "API":[
+      "reference/toplevel",
       "reference/big-map-reference",
       "reference/bitwise-reference",
       "reference/bytes-reference",
diff --git a/src/test/md_file_tests.ml b/src/test/md_file_tests.ml
index 9e301919b..3ceb8c3a6 100644
--- a/src/test/md_file_tests.ml
+++ b/src/test/md_file_tests.ml
@@ -125,6 +125,9 @@ let md_files = [
   "/gitlab-pages/docs/advanced/inline.md";
   "/gitlab-pages/docs/api/cli-commands.md";
   "/gitlab-pages/docs/api/cheat-sheet.md";
+  "/gitlab-pages/docs/reference/toplevel.md";
+  "/gitlab-pages/docs/reference/bitwise.md";
+  "/gitlab-pages/docs/reference/bytes.md";
   "/gitlab-pages/docs/reference/list.md";
   "/gitlab-pages/docs/reference/map.md";
   "/gitlab-pages/docs/reference/set.md";