diff --git a/README.md b/README.md
index 61f9c6b..127b33a 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,272 @@
 # APIlite
 
-A set of tools to simplify the work of creating backend APIs for your frontend projects. Includes tutorials, patterns and practical examples for creating projects based on REST APIs.
\ No newline at end of file
+A set of tools to simplify the work of creating backend APIs for your frontend projects. Includes tutorials, patterns and practical examples for creating projects based on REST APIs.
+
+## Basic usage
+
+For example, we create an API for calculator. So we create class `APIcalculator` and store in file `test/APIcalculator.php` where we defined each actions for API as public method.
+
+```
+<?php
+
+/**
+ * Class APIcalculator
+ *
+ * A calculator class that extends the functionality of TPsoft's APIlite.
+ * This class provides basic arithmetic operations and a few additional
+ * mathematical functions.
+ *
+ */
+
+require_once __DIR__ . '/../src/APIlite.php';
+
+class APIcalculator extends \TPsoft\APIlite\APIlite
+{
+
+	/**
+	 * Add two numbers.
+	 * Standard plus operation.
+	 *
+	 * @param float $a The first number.
+	 * @param float $b The second number.
+	 * @return float The sum of the two numbers.
+	 */
+	public function add(float $a, float $b): float
+	{
+		return $a + $b;
+	}
+
+	/**
+	 * Subtract two numbers.
+	 * Standard minus operation.
+	 *
+	 * @param float $a The first number.
+	 * @param float $b The second number.
+	 * @return float The difference of the two numbers.
+	 */
+	public function subtract(float $a, float $b): float
+	{
+		return $a - $b;
+	}
+
+	/**
+	 * Multiply two numbers.
+	 * Standard multiplication operation.
+	 *
+	 * @param float $a The first number.
+	 * @param float $b The second number.
+	 * @return float The product of the two numbers.
+	 */
+	public function multiply(float $a, float $b): float
+	{
+		return $a * $b;
+	}
+
+	/**
+	 * Divide two numbers.
+	 * Standard division operation. Throws an exception if dividing by zero.
+	 *
+	 * @param float $a The first number.
+	 * @param float $b The second number.
+	 * @return float The quotient of the two numbers. Throws an exception if dividing by zero.
+	 * @throws \Exception If dividing by zero.
+	 */
+	public function divide(float $a, float $b): float
+	{
+		if ($b == 0) {
+			throw new \Exception('Division by zero');
+		}
+		return $a / $b;
+	}
+}
+```
+
+It is important to extend the `APIcalculator` class with the `\TPsoft\APIlite\APIlite` class, which will provide the entire API servicing according to public methods along with JSON and HTML documentation. The HTML documentation is generated based on the documentation snippet for each method.
+
+## Outputs
+
+When you run this subfile through the webserver, you will see the JSON documentation in the browser
+
+```
+{
+  "name": "APIcalculator",
+  "html_version": "http://localhost/APIlite/test/APIcalculator.php?format=html",
+  "typescript_version": "http://localhost/APIlite/test/APIcalculator.php?format=typescript",
+  "actions": [
+    {
+      "name": "add",
+      "doc": "/**\r\n\t * Add two numbers.\r\n\t * Standard plus operation.\r\n\t *\r\n\t * @param float $a The first number.\r\n\t * @param float $b The second number.\r\n\t * @return float The sum of the two numbers.\r\n\t */",
+      "description": "Add two numbers.\nStandard plus operation.",
+      "params": [
+        {
+          "name": "a",
+          "type": "float",
+          "optional": false,
+          "default": null,
+          "doc": "The first number."
+        },
+        {
+          "name": "b",
+          "type": "float",
+          "optional": false,
+          "default": null,
+          "doc": "The second number."
+        }
+      ],
+      "return": "float"
+    },
+    {
+      "name": "subtract",
+      "doc": "/**\r\n\t * Subtract two numbers.\r\n\t * Standard minus operation.\r\n\t *\r\n\t * @param float $a The first number.\r\n\t * @param float $b The second number.\r\n\t * @return float The difference of the two numbers.\r\n\t */",
+      "description": "Subtract two numbers.\nStandard minus operation.",
+      "params": [
+        {
+          "name": "a",
+          "type": "float",
+          "optional": false,
+          "default": null,
+          "doc": "The first number."
+        },
+        {
+          "name": "b",
+          "type": "float",
+          "optional": false,
+          "default": null,
+          "doc": "The second number."
+        }
+      ],
+      "return": "float"
+    },
+    {
+      "name": "multiply",
+      "doc": "/**\r\n\t * Multiply two numbers.\r\n\t * Standard multiplication operation.\r\n\t *\r\n\t * @param float $a The first number.\r\n\t * @param float $b The second number.\r\n\t * @return float The product of the two numbers.\r\n\t */",
+      "description": "Multiply two numbers.\nStandard multiplication operation.",
+      "params": [
+        {
+          "name": "a",
+          "type": "float",
+          "optional": false,
+          "default": null,
+          "doc": "The first number."
+        },
+        {
+          "name": "b",
+          "type": "float",
+          "optional": false,
+          "default": null,
+          "doc": "The second number."
+        }
+      ],
+      "return": "float"
+    },
+    {
+      "name": "divide",
+      "doc": "/**\r\n\t * Divide two numbers.\r\n\t * Standard division operation. Throws an exception if dividing by zero.\r\n\t *\r\n\t * @param float $a The first number.\r\n\t * @param float $b The second number.\r\n\t * @return float The quotient of the two numbers. Throws an exception if dividing by zero.\r\n\t * @throws \\Exception If dividing by zero.\r\n\t */",
+      "description": "Divide two numbers.\nStandard division operation. Throws an exception if dividing by zero.",
+      "params": [
+        {
+          "name": "a",
+          "type": "float",
+          "optional": false,
+          "default": null,
+          "doc": "The first number."
+        },
+        {
+          "name": "b",
+          "type": "float",
+          "optional": false,
+          "default": null,
+          "doc": "The second number."
+        }
+      ],
+      "return": "float"
+    }
+  ]
+}
+```
+
+and there is also an HTML version available
+
+<img src="test/Example.APIcalculator.png" />
+
+To connect to the API from TypeScript (e.g. Vue application) it is possible to download the backend script
+
+```
+/**
+ * Generated by APIlite
+ * https://gitea.tpsoft.org/TPsoft.org/APIlite
+ *
+ * 2025-05-28 15:44:07 */
+
+export const backend = {
+	endpont: window.location.origin + "APIcalculator.php",
+
+	/* ----------------------------------------------------
+	 * General API call
+	 */
+	call(method, data, callback) {
+		var xhttp = new XMLHttpRequest();
+		xhttp.withCredentials = true;
+		xhttp.onreadystatechange = function() {
+			if (this.readyState == 4) {
+				if (this.status == 200) {
+					if (callback != null) callback(JSON.parse(this.responseText));
+				} else {
+					if (callback != null) callback({'status': 'ERROR', 'message': 'HTTP STATUS ' + this.status});
+				}
+			}
+		}
+		var form_data  = new FormData();
+		Object.keys(data).forEach(key => {
+			let val = data[key];
+			if (typeof val == 'object') val = JSON.stringify(val);
+			form_data.append(key, val);
+		});
+		xhttp.open('POST', this.endpont + '?action=' + method);
+		xhttp.send(form_data);
+	},
+
+	callPromise(method, data) {
+		return new Promise((resolve, reject) => {
+			this.call(method, data, function(response) {
+				if (response.status == 'OK') {
+					resolve(response.data);
+				} else {
+					reject(response.msg);
+				}
+			});
+		})
+	},
+
+	/* ----------------------------------------------------
+	 * API actions
+	 */
+	help() {
+		return this.callPromise('__HELP__', {});
+	},
+
+	add(a, b) {
+		return this.callPromise('add', {a: a, b: b});
+	},
+
+	subtract(a, b) {
+		return this.callPromise('subtract', {a: a, b: b});
+	},
+
+	multiply(a, b) {
+		return this.callPromise('multiply', {a: a, b: b});
+	},
+
+	divide(a, b) {
+		return this.callPromise('divide', {a: a, b: b});
+	},
+
+
+};
+
+```
+
+These outputs can also be generated in the command line as follows
+
+* for HTML`$> php APIcalculator.php --html`
+* for TypeScript`$> php APIcalculator.php --typescript`
diff --git a/src/APIlite.php b/src/APIlite.php
index ebb087b..92ef7fe 100644
--- a/src/APIlite.php
+++ b/src/APIlite.php
@@ -28,7 +28,7 @@ class APIlite
 			$this->doAction($_REQUEST['action']);
 		} else {
 			global $argv;
-			$switches = array_map('strtolower', $argv);
+			$switches = array_map('strtolower', is_array($argv) ? $argv : []);
 			if ((isset($_REQUEST['format']) && $_REQUEST['format'] == 'html') || in_array('--html', $switches)) {
 				$this->printHelpHTML();
 			} elseif ((isset($_REQUEST['format']) && $_REQUEST['format'] == 'typescript') || in_array('--typescript', $switches)) {
diff --git a/test/Example.APIcalculator.png b/test/Example.APIcalculator.png
new file mode 100644
index 0000000..217cb5a
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