diff --git a/rc/filetype/fidl.kak b/rc/filetype/fidl.kak
new file mode 100644
index 00000000..4164d838
--- /dev/null
+++ b/rc/filetype/fidl.kak
@@ -0,0 +1,79 @@
+# Detection
+hook global BufCreate .*\.fidl %{
+    set-option buffer filetype fidl
+}
+
+hook global WinSetOption filetype=fidl %<
+    require-module fidl
+    hook window ModeChange pop:insert:.* -group fidl-trim-indent fidl-trim-indent
+    hook window InsertChar \n -group fidl-indent fidl-indent-on-new-line
+    hook window InsertChar [)}] -group fidl-indent fidl-indent-on-closing
+    hook -once -always window WinSetOption filetype=.* %{ remove-hooks window fidl-.+ }
+>
+
+hook -group fidl-highlight global WinSetOption filetype=fidl %{
+    add-highlighter window/fidl ref fidl
+    hook -once -always window WinSetOption filetype=.* %{ remove-highlighter window/fidl }
+}
+
+provide-module fidl %§
+
+# Highlighters
+
+add-highlighter shared/fidl regions
+add-highlighter shared/fidl/code default-region group
+
+add-highlighter shared/fidl/string region \" (?<!\\)(\\\\)*" fill string
+
+add-highlighter shared/fidl/line_doc region ///(?!/) $ fill documentation
+add-highlighter shared/fidl/line_comment region // $ group
+add-highlighter shared/fidl/line_comment/comment fill comment
+add-highlighter shared/fidl/line_comment/todo regex TODO|FIXME: 0:meta
+
+add-highlighter shared/fidl/attributes region @[a-zA-Z] \b fill meta
+
+add-highlighter shared/fidl/code/keywords regex \b(as|bits|compose|const|enum|error|flexible|optional|library|protocol|resource|service|strict|struct|table|type|union|using)\b 0:keyword
+add-highlighter shared/fidl/code/types regex \b(array|bool|bytes?|client_end|float(32|64)|server_end|string|u?int(8|16|32|64)|vector)\b 0:type
+
+add-highlighter shared/fidl/code/literals group
+add-highlighter shared/fidl/code/literals/bool regex \b(true|false)\b 0:value
+add-highlighter shared/fidl/code/literals/decimal regex \b([0-9]+(\.[0-9]+)?)\b 0:value
+add-highlighter shared/fidl/code/literals/hexadecimal regex \b(0x[0-9a-fA-F])\b 0:value
+add-highlighter shared/fidl/code/literals/binary regex \b(0b[01])\b 0:value
+
+# Commands
+
+define-command -hidden fidl-trim-indent %{
+    # remove trailing white spaces
+    try %{ execute-keys -draft -itersel <a-x> s \h+$ <ret> d }
+}
+
+define-command -hidden fidl-indent-on-new-line %~
+    evaluate-commands -draft -itersel %@
+        try %{ # line comment
+            # copy the commenting prefix
+            execute-keys -draft k <a-x> s ^\h*/{2,}\h* <ret> yjghP
+        } catch %`
+            # preserve previous line indent
+            try %{ execute-keys -draft <semicolon> K <a-&> }
+            # align to opening ( or { if possible
+            try %+
+                execute-keys -draft <a-k> [)}] <ret> m <a-S> 1<a-&>
+            + catch %+
+                # indent after lines ending with ( or {
+                try %! execute-keys -draft k <a-x> <a-k> [({]$ <ret> j <a-gt> !
+            +
+        `
+        # remove trailing white spaces
+        try %{ execute-keys -draft k : fidl-trim-indent <ret> }
+    @
+~
+
+define-command -hidden fidl-indent-on-closing %~
+    evaluate-commands -draft -itersel %@
+        # align to opening ( or { when alone on a line
+        try %< execute-keys -draft <a-h> <a-k> ^\h*[)}]$ <ret> m <a-S> 1<a-&> >
+    @
+~
+
+§
diff --git a/test/indent/fidl/comments/cmd b/test/indent/fidl/comments/cmd
new file mode 100644
index 00000000..e3036a40
--- /dev/null
+++ b/test/indent/fidl/comments/cmd
@@ -0,0 +1 @@
+c<ret>
diff --git a/test/indent/fidl/comments/in b/test/indent/fidl/comments/in
new file mode 100644
index 00000000..691bd5b0
--- /dev/null
+++ b/test/indent/fidl/comments/in
@@ -0,0 +1,19 @@
+    // foo%( )
+
+    // foo%( )bar
+
+    //%( )
+
+    // %( )
+
+    // foo(%( )
+
+    /// foo%( )
+
+    /// foo%( )bar
+
+    ///%( )
+
+    /// %( )
+
+    /// foo(%( )
diff --git a/test/indent/fidl/comments/out b/test/indent/fidl/comments/out
new file mode 100644
index 00000000..2678cb23
--- /dev/null
+++ b/test/indent/fidl/comments/out
@@ -0,0 +1,29 @@
+    // foo
+    // 
+
+    // foo
+    // bar
+
+    //
+    //
+
+    //
+    // 
+
+    // foo(
+    // 
+
+    /// foo
+    /// 
+
+    /// foo
+    /// bar
+
+    ///
+    ///
+
+    ///
+    /// 
+
+    /// foo(
+    /// 
diff --git a/test/indent/fidl/comments/rc b/test/indent/fidl/comments/rc
new file mode 100644
index 00000000..d93242fb
--- /dev/null
+++ b/test/indent/fidl/comments/rc
@@ -0,0 +1,3 @@
+source "%val{runtime}/colors/default.kak"
+source "%val{runtime}/rc/filetype/fidl.kak"
+set buffer filetype fidl
diff --git a/test/indent/fidl/on-closing/cmd b/test/indent/fidl/on-closing/cmd
new file mode 100644
index 00000000..de4c4fba
--- /dev/null
+++ b/test/indent/fidl/on-closing/cmd
@@ -0,0 +1 @@
+c<ret>}
diff --git a/test/indent/fidl/on-closing/in b/test/indent/fidl/on-closing/in
new file mode 100644
index 00000000..8fc9031f
--- /dev/null
+++ b/test/indent/fidl/on-closing/in
@@ -0,0 +1,3 @@
+    foo {%( )
+
+    foo {%( );
diff --git a/test/indent/fidl/on-closing/out b/test/indent/fidl/on-closing/out
new file mode 100644
index 00000000..6ec01cc5
--- /dev/null
+++ b/test/indent/fidl/on-closing/out
@@ -0,0 +1,5 @@
+    foo {
+    }
+
+    foo {
+        };
diff --git a/test/indent/fidl/on-closing/rc b/test/indent/fidl/on-closing/rc
new file mode 100644
index 00000000..d93242fb
--- /dev/null
+++ b/test/indent/fidl/on-closing/rc
@@ -0,0 +1,3 @@
+source "%val{runtime}/colors/default.kak"
+source "%val{runtime}/rc/filetype/fidl.kak"
+set buffer filetype fidl
diff --git a/test/indent/fidl/on-newline/cmd b/test/indent/fidl/on-newline/cmd
new file mode 100644
index 00000000..e3036a40
--- /dev/null
+++ b/test/indent/fidl/on-newline/cmd
@@ -0,0 +1 @@
+c<ret>
diff --git a/test/indent/fidl/on-newline/in b/test/indent/fidl/on-newline/in
new file mode 100644
index 00000000..cda171e8
--- /dev/null
+++ b/test/indent/fidl/on-newline/in
@@ -0,0 +1,11 @@
+    foo%( )
+
+    @foo(%( )
+
+    foo {%( )
+
+    @foo(%( )) {
+
+    @foo(%( )"bar") {
+
+    foo {%( )};
diff --git a/test/indent/fidl/on-newline/out b/test/indent/fidl/on-newline/out
new file mode 100644
index 00000000..6ffa26b3
--- /dev/null
+++ b/test/indent/fidl/on-newline/out
@@ -0,0 +1,17 @@
+    foo
+    
+
+    @foo(
+        
+
+    foo {
+        
+
+    @foo(
+    ) {
+
+    @foo(
+        "bar") {
+
+    foo {
+    };
diff --git a/test/indent/fidl/on-newline/rc b/test/indent/fidl/on-newline/rc
new file mode 100644
index 00000000..d93242fb
--- /dev/null
+++ b/test/indent/fidl/on-newline/rc
@@ -0,0 +1,3 @@
+source "%val{runtime}/colors/default.kak"
+source "%val{runtime}/rc/filetype/fidl.kak"
+set buffer filetype fidl