diff --git a/.gitignore b/.gitignore
new file mode 100755
index 0000000..bbed0ee
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+.idea
+replacer.iml
+node_modules
diff --git a/package.json b/package.json
new file mode 100644
index 0000000..da5ce51
--- /dev/null
+++ b/package.json
@@ -0,0 +1,17 @@
+{
+  "name": "replacer",
+  "version": "1.0.0",
+  "description": "A command line utility to inject css and js files into an html file or to remove code based on conditions.",
+  "bin": "./replacer",
+  "scripts": {
+    "test": "tape tests/*.js | faucet"
+  },
+  "author": "Danny Moerkerke <danny@dannymoerkerke.nl>",
+  "license": "ISC",
+  "dependencies": {
+    "commander": "^2.9.0",
+    "faucet": "0.0.1",
+    "replacestream": "^4.0.0",
+    "tape": "^4.5.1"
+  }
+}
diff --git a/replacer b/replacer
new file mode 100755
index 0000000..48ebfda
--- /dev/null
+++ b/replacer
@@ -0,0 +1,103 @@
+#!/usr/bin/env node
+
+'use strict';
+
+const process = require('process');
+const fs = require('fs');
+const path = require('path');
+const replaceStream = require('replacestream');
+const program = require('commander');
+
+let cssFiles;
+let jsFiles;
+let removeCondition;
+
+const replaceFunc = (replacement) => {
+    return function() {
+        return replacement === undefined ? arguments[0] : replacement;
+    };
+};
+
+const handleError = (message) => {
+    console.error(message);
+    process.exit(1);
+};
+
+program
+    .version('1.0.0')
+    .option('-i, --input <input>', 'Input file')
+    .option('-o, --output <output>', 'Output file')
+    .option('-c, --css <css>', 'css file(s) to inject (file or directory)')
+    .option('-j, --js <js>', 'js file(s) to inject (file or directory)')
+    .option('-r, --remove <remove>', 'Remove condition')
+    .parse(process.argv);
+
+if(!program.input) {
+    handleError('Please specify an input file');
+}
+else {
+    try {
+        if(fs.lstatSync(program.input).isDirectory()) {
+            handleError(`'${program.input}' is a directory, please specify an input file`);
+        }
+    }
+    catch(e) {
+        handleError(`File '${program.input}' not found`);
+    }
+}
+
+if(!program.output) {
+    program.output = program.input;
+}
+
+if(program.js) {
+    const js = program.js;
+    
+    try {
+        if(fs.lstatSync(js).isDirectory()) {
+            jsFiles = fs.readdirSync(js)
+                .filter(file => file.substr(-3) === '.js')
+                .map(file => `<script src="${js}/${file}"></script>`)
+                .join('\n');
+        }
+        else if(fs.lstatSync(js).isFile()) {
+            jsFiles = `<script src="${js}"></script>`;
+        }
+    }
+    catch(e) {
+        handleError(`File or folder '${js}' not found`);
+    }
+}
+
+if(program.css) {
+    const css = program.css;
+    
+    try {
+        if(fs.lstatSync(css).isDirectory()) {
+            cssFiles = fs.readdirSync(css)
+                .filter(file => file.substr(-4) === '.css')
+                .map(file => `<link rel="stylesheet" href="${css}/${file}">`)
+                .join('\n');
+        }
+        else if(fs.lstatSync(css).isFile()) {
+            cssFiles = `<link rel="stylesheet" href="${css}">`;
+        }
+    }
+    catch(e) {
+        handleError(`File or folder '${css}' not found`);
+    }
+}
+
+if(program.remove) {
+    removeCondition = program.remove.split(':').pop();
+}
+
+const replaceJs = replaceFunc(jsFiles);
+const replaceCss = replaceFunc(cssFiles);
+const regex = new RegExp(`(<!\\-\\- remove:${removeCondition} \\-\\->)([\\s\\S]*?)(<!\\-\\- endremove \\-\\->)`, 'gm');
+
+fs.createReadStream(path.join(__dirname, program.input))
+    .pipe(replaceStream(/(<!\-\- inject:js \-\->)([\s\S]*?)(<!\-\- endinject \-\->)/gm, replaceJs))
+    .pipe(replaceStream(/(<!\-\- inject:css \-\->)([\s\S]*?)(<!\-\- endinject \-\->)/gm, replaceCss))
+    .pipe(replaceStream(regex, ''))
+    .pipe(fs.createWriteStream(path.join(__dirname, program.output)));
\ No newline at end of file
diff --git a/tests/test.js b/tests/test.js
new file mode 100755
index 0000000..6db9c29
--- /dev/null
+++ b/tests/test.js
@@ -0,0 +1,162 @@
+"use strict";
+
+const fs = require('fs');
+const path = require('path');
+const exec = require('child_process').exec;
+const test = require('tape');
+
+const before = test;
+const after = test;
+const tmpDir = 'tests/tmp';
+const inputFile = `${tmpDir}/index.html`;
+const outputFile = `${tmpDir}/output.html`;
+const cssFiles = ['styles1.css', 'styles2.css', 'styles3.css'];
+const jsFiles = ['script1.js', 'script2.js', 'script3.js'];
+
+const setup = () => {
+
+    try {
+        fs.lstatSync(tmpDir);
+    }
+    catch(e) {
+        fs.mkdirSync(tmpDir);
+    }
+    
+    fs.writeFileSync(`${inputFile}`, `
+        <!DOCTYPE html>
+            <html>
+                <head>
+                    <meta charset="utf-8">
+                    <title>Replacer</title>
+                    <base href="/" />
+                    <meta name="viewport" content="width=device-width, initial-scale=1">
+                    
+                    <!-- inject:css -->
+                    <link rel="stylesheet" href="/client/css/styles.css">
+                    <!-- endinject -->
+            
+                </head>
+                <body>
+            
+                    <div></div>
+            
+                    <!-- remove:development -->
+                    <script src="lib/profiler.js"></script>
+                    <!-- endremove -->
+            
+                    <script src="/src/jquery.js"></script>
+                    
+                    <!-- inject:js -->
+                    <script src="/client/js/build.js"></script>
+                    <!-- endinject -->
+            
+                    <!-- remove:production -->
+                    <script src="http://localhost:35729/livereload.js?snipver=1"></script>
+                    <!-- endremove -->
+                </body>
+            </html>
+
+    `);
+    
+    cssFiles.forEach((file) => {
+        fs.writeFileSync(`${tmpDir}/${file}`, `
+            body {
+                padding: 0;
+                margin: 10px;
+            }
+        `);
+    });
+    
+    jsFiles.forEach((file) => {
+        fs.writeFileSync(`${tmpDir}/${file}`, `
+            console.log('${file}');
+        `);
+    });
+};
+
+before('test setup', (t) => {
+    setup();
+    t.end();
+});
+
+test('test injection of all stylesheets in directory', (t) => {
+    exec(`./replacer -i ${inputFile} -o ${outputFile} -c ${tmpDir}`, (err) => {
+
+        fs.readFile(`${outputFile}`, (err, data) => {
+            cssFiles.forEach((file) => {
+                t.equal(true, data.indexOf(`${tmpDir}/${file}`) !== -1, `expect ${file} to be injected`);
+            });
+
+            t.end();
+        });
+    });
+});
+
+test('test injection of all javascripts in directory', (t) => {
+    exec(`./replacer -i ${inputFile} -o ${outputFile} -j ${tmpDir}`, (err) => {
+
+        fs.readFile(`${outputFile}`, (err, data) => {
+            jsFiles.forEach((file) => {
+                t.equal(true, data.indexOf(`${tmpDir}/${file}`) !== -1, `expect ${file} to be injected`);
+            });
+
+            t.end();
+        });
+    });
+});
+
+test('test injection of single stylesheet', (t) => {
+    exec(`./replacer -i ${inputFile} -o ${outputFile} -c ${tmpDir}/${cssFiles[0]}`, (err) => {
+
+        fs.readFile(`${outputFile}`, (err, data) => {
+            t.equal(true, data.indexOf(`${tmpDir}/${cssFiles[0]}`) !== -1, `expect ${cssFiles[0]} to be injected`);
+
+            t.end();
+        });
+    });
+});
+
+test('test injection of single javascript', (t) => {
+    exec(`./replacer -i ${inputFile} -o ${outputFile} -j ${tmpDir}/${jsFiles[0]}`, (err) => {
+
+        fs.readFile(`${outputFile}`, (err, data) => {
+            t.equal(true, data.indexOf(`${tmpDir}/${jsFiles[0]}`) !== -1, `expect ${jsFiles[0]} to be injected`);
+
+            t.end();
+        });
+    });
+});
+
+test('test removal of development code', (t) => {
+    exec(`./replacer -i ${inputFile} -o ${outputFile} -r development`, (err) => {
+        const devRegex = new RegExp('(<!\\-\\- remove:development \\-\\->)([\\s\\S]*?)(<!\\-\\- endremove \\-\\->)');
+        const prodRegex = new RegExp('(<!\\-\\- remove:production \\-\\->)([\\s\\S]*?)(<!\\-\\- endremove \\-\\->)');
+        
+        fs.readFile(`${outputFile}`, (err, data) => {
+            t.equal(false, devRegex.test(data), `expect development code to be removed`);
+            t.equal(true, prodRegex.test(data), `expect production code to not be removed`);
+            
+            t.end();
+        });
+    });
+});
+
+test('test removal of production code', (t) => {
+    exec(`./replacer -i ${inputFile} -o ${outputFile} -r production`, (err) => {
+        const prodRegex = new RegExp('(<!\\-\\- remove:production \\-\\->)([\\s\\S]*?)(<!\\-\\- endremove \\-\\->)');
+        const devRegex = new RegExp('(<!\\-\\- remove:development \\-\\->)([\\s\\S]*?)(<!\\-\\- endremove \\-\\->)');
+
+        fs.readFile(`${outputFile}`, (err, data) => {
+            t.equal(false, prodRegex.test(data), `expect production code to be removed`);
+            t.equal(true, devRegex.test(data), `expect development code to not be removed`);
+
+            t.end();
+        });
+    });
+});
+
+after('test cleanup', (t) => {
+    exec(`rm -rf ${tmpDir}`, () => {
+        t.end();
+    });
+});
\ No newline at end of file