Looking through my post, I find two questions in it:
- How websites track couriers through multiple sites and delivery partners, and
- How are parcels from different post offices tracked?
Let me answer the second question first:
2) How are parcels from different post offices tracked?
Each mail network that deserves its salt will use some kind of technological solution for tracking packets - capturing information, for example, where they came from, what intermediate hop they are now in, and where they will be delivered. You can only get this information for packages that have a tracking number, so that a registered post or equivalent can be tracked, but a simple stamped post may not be tracked.
For example, India Post allows you to track by consignment number . The tracking number is essentially associated with a barcode that is physically implanted into the package (I think barcode stickers). A group of parcels at any stage could be called a collection (possibly inside its own container), and each batch has a bar code. Thus, each time deliveries move between hops, the tracking information is updated based on either the dispatch barcode or the parcel barcode. At each stage, prior to actual delivery, sequential jumps are thus identified.
Just as banks and ATMs are connected to a centralized infrastructure, so you cannot withdraw all your money from different bank branches multiple times; Each mail branch does not have its own tracking solution, they are all connected to centralized servers when they are part of the same mail network.
Sometimes these mail networks may expose their APIs, while in other cases, independent hackers may write wrappers around their user interface capabilities that have been exposed to retail users for packet tracking. For example, here's a github project that helps you get tracking information from India Post in API format .
Now, returning to the first question:
1) How websites track a courier through multiple sites and delivery partners.
Many delivery partners can provide their APIs for packages, while others can do this through a user form on their website. For example, Delhivery in India has its own package tracking APIs .
Thus, each generic courier tracking site must either integrate the API from the courier agency or put an Iframe where it loads the delivery tracking mechanism.
A simple google track courier can give you a list of many such sites. By choosing one random case, TrackCourier.in , itโs easy to see that they wrote one PHP page for one courier that they have, embedding an iframe for the courier agency on their site.
OP says in the comments,
I donโt think 17track or trackitonline.ru use iframes ... Then these tracking sites should only work with the post office to gain access to the entire tracking system.
Unfortunately, this is not the case. When browsing through the numerous sites mentioned by OPs, sites clearly indicate that they are merging new channels on their own, and this usually happens through the API.
So trackitonline mentions its page : Tracking. This is usually a summary of information provided by official supplier companies using their public or internal syatems and databases, with the exception of some transport companies that do not have such systems.
And 17track has it on its website : Started with dozens of postal carriers and integrated 100 border logistics providers.
(I emphasized the relevant information in italics)
In fact, all such sites either have preferential access to the systems of mail companies, or have developed tools to integrate their functions using iframe and other UI hackers.