diff --git a/bin/downcase b/bin/downcase
new file mode 100755
index 0000000..d70013b
--- /dev/null
+++ b/bin/downcase
@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+exec tr '[:upper:]' '[:lower:]'
diff --git a/bin/upcase b/bin/upcase
new file mode 100755
index 0000000..960a452
--- /dev/null
+++ b/bin/upcase
@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+exec tr '[:lower:]' '[:upper:]'