DHL PHP SDK is an unofficial resource that wraps some of the DHL SOAP API's functions, including shipment and label creation. Even though the SDK is unofficial, developers still need a DHL developer account (and possibly a DHL Intraship Account) to use the API.
Postmaster, a cloud-based, small package shipping platform for SMBs and eCommerce companies, has announced the launch of the public beta version of the Postmaster API. The Postmaster API was designed to allow easy integration of multiple shipping carriers into e-commerce systems as well as to help companies save time and money throughout the entire shipping process.
The Saia API helps this first class less-than-a-truckload (LTL) carrier deliver by giving developers access to tracking information inside their applications. Rate quotes and pick up scheduling are also accessible. The API uses SOAP and XML, and is implemented using Microsoft's .NET Framework.
Who needs a tracking service when you can just hop on the USPS, FedEx, UPS, or DHL website (or whoever your carrier is) and just track? Maybe you. The Trackthis API integrates an amazing array of functions into your application. The API webpage lists over 10 carriers you can get notifications for.