If you're integrating with QuickBooks Online, you need to use OAuth. It's ridiculously trivial to get started with OAuth and QuickBooks Online if you use existing code - here's an open-source QuickBooks PHP DevKit which should be helpful (disclaimer - I'm the author):
If you follow the quick-start guide:
You should be up and running within 15 minutes or so. It's as easy as registering with Intuit, changing a few configuration variables, and clicking a "Connect to QuickBooks" button.
You end up with some pretty simple looking code like this:
$CustomerService = new QuickBooks_IPP_Service_Customer();
$Customer = new QuickBooks_IPP_Object_Customer();
$Customer->setTitle('Mr');
$Customer->setGivenName('Keith');
$Customer->setMiddleName('R');
$Customer->setFamilyName('Palmer');
$Customer->setDisplayName('Keith R Palmer ' . mt_rand(0, 1000));
// Email
$PrimaryEmailAddr = new QuickBooks_IPP_Object_PrimaryEmailAddr();
$PrimaryEmailAddr->setAddress('[email protected]');
$Customer->setPrimaryEmailAddr($PrimaryEmailAddr);
if ($resp = $CustomerService->add($Context, $realm, $Customer))
{
print('Our new customer ID is: [' . $resp . '] (name "' . $Customer->getDisplayName() . '")');
}
else
{
print($CustomerService->lastError($Context));
}
There are tons of additional examples here: