diff --git a/cli.js b/cli.js
index a8e1db6..fc8f2b0 100755
--- a/cli.js
+++ b/cli.js
@@ -2,19 +2,26 @@
 'use strict';
 const meow = require('meow');
 const opn = require('opn');
+const getStdin = require('get-stdin');
+const tempWrite = require('temp-write');
+const fileType = require('file-type');
 
 const cli = meow(`
 	Usage
 	  $ opn <file|url> [--wait] [-- <app> [args]]
+	  $ stdout | opn [--wait] [--ext] [-- <app> [args]]
 
 	Options
 	  --wait  Wait for the app to exit
+	  --ext   File extension for stdin
 
 	Examples
 	  $ opn http://sindresorhus.com
 	  $ opn http://sindresorhus.com -- firefox
 	  $ opn http://sindresorhus.com -- 'google chrome' --incognito
 	  $ opn unicorn.png
+	  $ cat ./image.png | opn
+	  $ echo '[]' | opn --ext json
 `, {
 	default: {
 		wait: false
@@ -23,4 +30,19 @@ const cli = meow(`
 
 cli.flags.app = cli.input.slice(1);
 
-opn(cli.input[0], cli.flags);
+const input = cli.input[0];
+
+if (!input && process.stdin.isTTY) {
+	console.error('Input required');
+	process.exit(1);
+}
+
+if (input) {
+	opn(input, cli.flags);
+} else {
+	getStdin.buffer().then(stdin => {
+		const type = fileType(stdin);
+		const ext = (cli.flags.ext || type && type.ext || 'txt');
+		opn(tempWrite.sync(stdin, `opn.${ext}`), cli.flags);
+	});
+}
diff --git a/package.json b/package.json
index d382de9..c4bc3a3 100644
--- a/package.json
+++ b/package.json
@@ -51,8 +51,11 @@
     "file"
   ],
   "dependencies": {
+    "file-type": "^3.6.0",
+    "get-stdin": "^5.0.1",
     "meow": "^3.7.0",
-    "opn": "^4.0.0"
+    "opn": "^4.0.0",
+    "temp-write": "^2.1.0"
   },
   "devDependencies": {
     "ava": "*",
diff --git a/readme.md b/readme.md
index 31172a6..65b70c5 100644
--- a/readme.md
+++ b/readme.md
@@ -17,15 +17,19 @@ $ opn --help
 
   Usage
     $ opn <file|url> [--wait] [-- <app> [args]]
+    $ stdout | opn [--wait] [--ext] [-- <app> [args]]
 
   Options
     --wait  Wait for the app to exit
+    --ext   File extension for stdin
 
   Examples
     $ opn http://sindresorhus.com
     $ opn http://sindresorhus.com -- firefox
     $ opn http://sindresorhus.com -- 'google chrome' --incognito
     $ opn unicorn.png
+    $ cat ./image.png | opn
+    $ echo '[]' | opn --ext json
 ```