diff --git a/API.md b/API.md
index de20c7d..b61ead1 100644
--- a/API.md
+++ b/API.md
@@ -231,6 +231,33 @@ A map of search filters, indexed by name.
 
 ---
 
+### Item compression
+
+`i3` is capable of reducing the item list size by compressing a group of items.
+
+#### `i3.compress(item, def)`
+
+Adds a new group of items to compress.
+
+- `item` is the item that serve as stereotype for the group of compressed items.
+- `def` is a table specifying the substring replace patterns to be used.
+
+Example:
+
+```Lua
+i3.compress("default:diamondblock", {
+	replace = "diamond",
+	by = {"bronze", "copper", "gold", "steel", "tin"}
+})
+
+```
+
+#### `i3.get_compress_groups()`
+
+Returns a map of all compressed item groups, indexed by stereotypes.
+
+---
+
 ### Miscellaneous
 
 #### `i3.get_recipes(item)`
diff --git a/etc/api.lua b/etc/api.lua
index f261c97..45edbf3 100644
--- a/etc/api.lua
+++ b/etc/api.lua
@@ -285,4 +285,38 @@ i3.add_search_filter("groups", function(item, groups)
 	return has_groups
 end)
 
+function i3.compress(item, def)
+	if not true_str(item) then
+		return err "i3.compress: item name missing"
+	end
+
+	if not is_table(def) then
+		return err "i3.compress: replace definition missing"
+	end
+
+	if not true_str(def.replace) then
+		return err "i3.compress: replace string missing"
+	end
+
+	if not is_table(def.by) then
+		return err "i3.compress: replace substrings missing"
+	end
+
+	local t = {}
+	i3.compress_groups[item] = i3.compress_groups[item] or {}
+
+	for _, str in ipairs(def.by) do
+		local it = item:gsub(def.replace, str)
+
+		insert(t, it)
+		insert(i3.compress_groups[item], it)
+
+		i3.compressed[it] = true
+	end
+end
+
+function i3.get_compress_groups()
+	return i3.compress_groups
+end
+
 return set_fs, i3.set_tab
diff --git a/init.lua b/init.lua
index 1fe015e..7d50377 100644
--- a/init.lua
+++ b/init.lua
@@ -291,4 +291,5 @@ if i3.progressive_mode then
 end
 
 --dofile(modpath .. "/tests/test_tabs.lua")
+--dofile(modpath .. "/tests/test_compression.lua")
 --dofile(modpath .. "/tests/test_custom_recipes.lua")
diff --git a/tests/test_compression.lua b/tests/test_compression.lua
new file mode 100644
index 0000000..7e5bb73
--- /dev/null
+++ b/tests/test_compression.lua
@@ -0,0 +1,4 @@
+i3.compress("default:diamondblock", {
+	replace = "diamond",
+	by = {"bronze", "copper", "gold", "steel", "tin"}
+})