"Connect us to all the courier partners" sounds like one task. In practice it is five, and the difficulty is rarely in the connection itself — it is in making several partners behave consistently enough that your staff and customers see one coherent system.

1. Rate shopping

Picking the right partner per shipment means comparing live rates across weight, dimensions, destination pincode, service level and any surcharges each partner applies. The logic also has to account for coverage — the cheapest partner is irrelevant if they do not serve the destination. Decide up front whether the choice is automatic, suggested, or left to an operator.

2. Booking and label generation

Each partner returns their own tracking identifier and their own label format, in their own layout and size. Your system has to store the identifier against your consignment and print a label that scans correctly at the partner's hub. Label problems are one of the most common causes of shipments stalling.

3. Tracking normalisation

This is where most of the hidden work lives. Every partner has their own status vocabulary, and they rarely map cleanly onto each other. One partner's "In Transit" may cover what another splits across three statuses. If you pass raw partner statuses through to customers, your tracking page becomes inconsistent and support calls go up.

The fix is a status model of your own, with each partner's statuses mapped into it. That mapping is a maintained asset, not a one-off task.

4. COD reconciliation

Cash on delivery is where integrations most often leak money. Partners remit on different cycles, with different deduction rules, in files with different formats. Reconciling what was collected against what was remitted against what you invoiced needs to be automated, or it quietly becomes somebody's full-time job.

5. Failure handling

Partner APIs go down, rate-limit you, time out, or return success and then do nothing. A serious integration needs retries with backoff, idempotency so a retry cannot create a duplicate shipment, a queue for bookings that could not complete, and alerting so somebody knows before customers do.

What to plan for

• Partner APIs change, sometimes without much notice
• Sandbox behaviour often differs from production
• Credentials and rate cards need somewhere safe to live
• Each new partner is incremental work, not a plug-in

The realistic view

A courier aggregator is genuinely valuable — one interface, better rates, less partner lock-in. But it is an ongoing integration commitment rather than a feature you finish. Budget for maintenance from the start, and the system will keep earning its place.