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+# Using alternate hosts to check for dead links
+
+InternetArchiveBot comes with a testdeadlink.php file that can be installed on different machines and accessed through their web servers.
+
+The testdeadlink.php checks all URLs concurrently.
+
+## Installation
+1. Clone the internetarchivebot repository to any desired directory on the target host machine.
+2. Run composer to install the dependencies.
+3. Copy, or symlink, the vendor directory to the directly above the web server's html root directory.
+4. Copy, or symlink, the testdeadlink.php to the html root directory.
+5. Create an accessConfig.php in the parent folder to the html root directory.
+6. Set the variable **$accessCodes** as an array of authorization strings to be used for authorizing use of the endpoint.  The strings can be anything you wish it to be.
+
+Note: The CheckIfDead library requires an environment with PHP 7.3 or newer.  Installing TOR on the host is recommended.
+
+Note: It is recommended to set the gateway timeout and PHP execution timeout values to 5 minutes or higher while allowing multiple concurrent requests on the web server.
+
+## Using the endpoint
+InternetArchiveBot makes use of this endpoint when pointed to the endpoint.  If you would like to use the endpoint for other reasons, here's what you need to know.
+
+All requests are only handled via POST requests.  Every request requires an '**authcode**' value to be specified containing one of the strings stored in **$accessCodes** as explained above.
+
+The endpoint can be reached simply by calling the URL for it on the web server.  Responses are in JSON.
+
+Simply calling the testdeadlink.php file will have it return:
+```angular2html
+{
+    "error": "nocommand",
+    "errormessage": "You must provide inputs.",
+    "servetime": 0.0362
+}
+```
+To have it check URLs, you must pass one or more URLs via the '**urls**' parameter.  Multiple URLs can be seperated by newlines in the POST request.
+
+When the endpoint finishes checking all URLs, it will produce output like below:
+```angular2html
+{
+    "https:\/\/en.wikipedia.org\/nothing": true,
+    "https:\/\/en.wikipedia.org": false,
+    "errors": {
+        "https:\/\/en.wikipedia.org\/nothing": "RESPONSE CODE: 404"
+    }
+}
+```
+Values with "true" are considered "dead".
+
+You can add '**returncodes=1**' to the POST request to replace the true/false return values with actual HTTP codes.
+Example response:
+```angular2html
+{
+    "https:\/\/en.wikipedia.org\/nothing": 404,
+    "https:\/\/en.wikipedia.org": 200,
+    "errors": {
+        "https:\/\/en.wikipedia.org\/nothing": "RESPONSE CODE: 404"
+    }
+}
+```