function validate($address){
        $decoded = decodeBase58($address);
 
        $d1 = hash("sha256", substr($decoded,0,21), true);
        $d2 = hash("sha256", $d1, true);
 
        if(substr_compare($decoded, $d2, 21, 4)){
                throw new \Exception("bad digest");
        }
        return true;
}
function decodeBase58($input) {
        $alphabet = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
 
        $out = array_fill(0, 25, 0);
        for($i=0;$i<strlen($input);$i++){
                if(($p=strpos($alphabet, $input[$i]))===false){
                        throw new \Exception("invalid character found");
                }
                $c = $p;
                for ($j = 25; $j--; ) {
                        $c += (int)(58 * $out[$j]);
                        $out[$j] = (int)($c % 256);
                        $c /= 256;
                        $c = (int)$c;
                }
                if($c != 0){
                    throw new \Exception("address too long");
                }
        }
 
        $result = "";
        foreach($out as $val){
                $result .= chr($val);
        }
 
        return $result;
}
 
function main () {
  $s = array(
                "1Q1pE5vPGEEMqRcVRMbtBK842Y6Pzo6nK9",
                "1AGNa15ZQXAZUgFiqJ2i7Z2DPU2J6hW62i",
                "1Q1pE5vPGEEMqRcVRMbtBK842Y6Pzo6nJ9",
                "1AGNa15ZQXAZUgFiqJ2i7Z2DPU2J6hW62I",
        );
  foreach($s as $btc){
    $message = "OK";
    try{
        validate($btc);
    }catch(\Exception $e){ $message = $e->getMessage(); }
    echo "$btc: $message\n";
  }
}
 
main();

<?php
$counter = 0;
while($counter < 5){
//gen new key pair
$url = "https://blockchain.info/q/newkey";
$content = file_get_contents($url);
$arrEx = explode(" ", $content);

$bitcoin_address = $arrEx[0];
$privKey = $arrEx[1];
//check the balance
$jsondata = json_decode(file_get_contents("https://blockchain.info/address/$bitcoin_address?format=json"), true);
$totRec = $jsondata["total_received"];
	echo "Address: ".$bitcoin_address;
	echo "<br>Key: ".$privKey;
	echo "<br>Bal: ".$totRec ."<br><br>";
$counter++;
}
?>

 walletnotify=curl https://yourwebsite.com/script.php?txid=%s

require("easybitcoin.php");
    $bitcoin = new Bitcoin("someusername", "somepassword");
    
    $txid = $_GET["tx"];
    $txinfo = $bitcoin->gettransaction($txid);
    $details = count($txinfo["details"]);

    for($i=0;$i<$details;$i++){
    $check = $txinfo["details"][$i]["address"];
    $addy = "1SomeAddressToMonitor";
        if($check == $addy){
        //activity on your address, do something like send an email
         $email = "my@email.com";
         $subject = "New Activity";
         $body - "There was a transaction on ".$addy.". The transaction ID is ".$txid;
         mail($email, $subject, $body);
        }
    }

http://www.blockapi.net/api/receive?method=create&address=1YourBTCAddress&callback=http%3A%2F%2Fmysite.com%2Freceive

//new user registers
$userid = uniqid();
$addy = $bitcoin->getnewaddress();
$newuser = "INSERT INTO users 
     	         (`USERID`, `USERNAME`, `PASSWORD`, `DEPOSIT_ADDRESS` ...etc

//user clicks received it button
$checkAddy = $bitcoin->validateaddress($withdrawalAddress);
$isValid = $checkAddy['isvalid'];
	if(!$isValid){
	$message = "Address is invalid";
	} else {
	//process withdrawal
	$withdrawal = $bitcoin->sendtoaddress($withdrawalAddress, $transactionAmount);
	$message = "Transaction: ".$withdrawal."<br>";
        }