diff --git a/Project.toml b/Project.toml
index 9ba9c24..4fb7c8a 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,6 +1,6 @@
 name = "ITensorFormatter"
 uuid = "b6bf39f1-c9d3-4bad-aad8-593d802f65fd"
-version = "0.2.28"
+version = "0.3.0"
 authors = ["ITensor developers <support@itensor.org> and contributors"]
 
 [workspace]
diff --git a/docs/Project.toml b/docs/Project.toml
index 89f1e1a..ee1e8f9 100644
--- a/docs/Project.toml
+++ b/docs/Project.toml
@@ -7,4 +7,4 @@ path = ".."
 
 [compat]
 Documenter = "1"
-ITensorFormatter = "0.2.27"
+ITensorFormatter = "0.2.27, 0.3"
diff --git a/examples/Project.toml b/examples/Project.toml
index 897cf16..4919ca3 100644
--- a/examples/Project.toml
+++ b/examples/Project.toml
@@ -5,4 +5,4 @@ ITensorFormatter = "b6bf39f1-c9d3-4bad-aad8-593d802f65fd"
 path = ".."
 
 [compat]
-ITensorFormatter = "0.2"
+ITensorFormatter = "0.2, 0.3"
diff --git a/src/main.jl b/src/main.jl
index a16919c..17571fe 100644
--- a/src/main.jl
+++ b/src/main.jl
@@ -143,13 +143,25 @@ function process_args(argv)
     return (; paths, format, format_yaml)
 end
 
+function format_stdin()
+    content = read(stdin, String)
+    content = organize_import_blocks_string(content)
+    content = JuliaFormatter.format_text(content; JULIAFORMATTER_OPTIONS...)
+    content = Runic.format_string(content)
+    write(stdout, content)
+    return 0
+end
+
 """
 $(help_markdown())
 """
 function main(argv)
     (; paths, format, format_yaml) = process_args(argv)
     !format && return 0
-    isempty(paths) && return error("No input paths provided.")
+    if isempty(paths)
+        format_stdin()
+        return 0
+    end
     jlfiles = filterpaths(isjlfile, paths)
     yamlfiles = format_yaml ? filterpaths(isyamlfile, paths) : String[]
     projectomls = filterpaths(isprojecttoml, paths)
diff --git a/test/Project.toml b/test/Project.toml
index 9ab3467..1ae0af5 100644
--- a/test/Project.toml
+++ b/test/Project.toml
@@ -12,7 +12,7 @@ path = ".."
 
 [compat]
 Aqua = "0.8"
-ITensorFormatter = "0.2"
+ITensorFormatter = "0.2, 0.3"
 ITensorPkgSkeleton = "0.3.42"
 JuliaSyntax = "0.4.10, 1"
 SafeTestsets = "0.1"
diff --git a/test/test_basics.jl b/test/test_basics.jl
index 9e6eeb6..b22a3c0 100644
--- a/test/test_basics.jl
+++ b/test/test_basics.jl
@@ -212,7 +212,27 @@ end
     end
 
     @testset "no arguments" begin
-        @test_throws ErrorException ITensorFormatter.main(String[])
+        mktempdir() do dir
+            _, fake_stdin = mktemp(dir)
+            _, fake_stdout = mktemp(dir)
+
+            redirect_stdio(; stdin = fake_stdin, stdout = fake_stdout) do
+                write(stdin, "using Zebra: z\nusing Alpha: a\nx = 1\n")
+                seek(stdin, 0)
+
+                ITensorFormatter.main(String[])
+
+                seek(stdout, 0)
+                result = read(stdout, String)
+
+                @test contains(result, "using Alpha: a")
+                @test contains(result, "using Zebra: z")
+                # Alpha should come before Zebra
+                @test findfirst("Alpha", result) < findfirst("Zebra", result)
+                # Non-import code preserved
+                @test contains(result, "x = 1")
+            end
+        end
     end
 
     @testset "nonexistent path" begin