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Master Bill of Lading (Master B/L): Use It for Container Tracking in Real-Time
Imagine you’re in charge of logistics for your company and you’re trying to transport the company’s product over international waters. Now, you can’t tell the location of your container, and the company’s goods could be anywhere.
Your freight forwarder gives you a container number, but when you punch it into tracking portals, nothing is coming up, no departure time, no vessel name, not even a port-of-origin ping. You risk demurrage fees, idle labor, and worst of all, missed market windows.
Enter the Master Bill of Lading, your forgotten yet powerful ally. The moment it’s issued by the carrier, tracking becomes possible, long before containers get numbers or show up in EDI systems. It transforms invisible cargo into live, trackable data.
Master Bill of Lading: What Is It?
The Master Bill of Lading (MBL) is a detailed document generated by the carrier or the shipping company. It is usually issued to the party that books the services of the shipping agency, like the freight forwarder. A lot of people mistake the freight forwarder as the issuer of the MBL, but that’s a misconception.
The MBL is a very important document that must be included in the contract between the shipping agency and the Non-Vessel Operating Common Carrier (NVOCC). Legally, the MBL performs three critical roles:
- A Receipt of Goods – It confirms the carrier has physically received the cargo on board the vessel.
- A Document of Title – It indicates ownership and can be transferred or endorsed, enabling goods to be sold while in transit.
- A Contract of Carriage – It sets the terms between the carrier and the shipper, forming a legally binding agreement.
This shows that the MBL is more than just a tracking tool; it’s a binding legal document recognized internationally.
But what makes it particularly relevant for tracking is its early issuance. The Master B/L is created and sent to the appropriate parties once the carrier receives the cargo.
Modern shipping platforms leverage this document to access carrier data feeds, port notifications, and Automatic Identification System (AIS) signals. What this means is that you can monitor shipments from the moment they leave the export port, sometimes days ahead of traditional container-based tracking.
In practical terms, when you enter your Master B/L into a tracking platform, you’re tapping into a carrier-verified digital thread. It ties together vessel schedules, port call data, and even customs handovers, offering a far more integrated view than isolated container tracking alone.
Step-by-Step: Using Your Master Bill of Lading for Container Tracking in Real-Time
Once you know how to use the Master Bill of Lading to track your cargo in real-time, it makes everything much easier, and you can be more assured about the safety of your cargo. We’ll show you how to use the MBL for tracking purposes in very simple steps.
Step 1: Obtain the Master B/L Number Early
The Master B/L is usually among the first things that are generated by the carrier. However, most people don’t bother to get it because it contains general information about the vessel, instead of more consignee-specific information. Ensure you get the MBL number early, and you can start your tracking process.
Step 2: Choose a JSONCargo for Master B/L Tracking
Instead of relying on scattered carrier portals or multiple platforms, JsonCargo gives you one unified API tracking tool. Enter your Master B/L, and JsonCargo connects directly to carrier data and global AIS vessel tracking, giving you real-time visibility.
Step 3: Input the Master B/L Details
Using JsonCargo is straightforward. Simply input the MBL number into the API request, and you’ll immediately start receiving location and movement data about your cargo.
Step 4: Access Real-Time Updates Of your Container Status
JsonCargo updates the cargo status continuously using both carrier feeds and AIS vessel data. You can see where the vessel is right now and the estimated arrival times at the destination port.
Step 5: Set Alerts and Notifications
While JsonCargo itself doesn’t send notifications, you can easily set up your own alerts. For example, you can connect the JsonCargo API to your internal systems, spreadsheets, or email tools to automatically notify your team when there are updates to the cargo status.
Example: How to Track a container using Master BL
To track a container with Master BL, just make an API request with the BL number to our API endpoint (Tracking with Bill of Lading):
GET http://api.jsoncargo.com/api/v1/containers/bol/{bill_of_lading_number}?shipping_line={shipping_line_name}
Example Response:
{
"data": {
"bill_of_lading": "SZPE72846000",
"shipping_line_name": "Hyundai Merchant Marine",
"shipping_line_id": "0012",
"associated_containers": 16,
"associated_container_numbers": [
"CAIU9933760",
"CLKU5004260",
"GAOU6162340",
"HDMU6653051",
"HDMU6836237",
"HMMU6053862",
"HMMU6541677",
"HMMU6668297",
"KOCU4503822",
"KOCU4771471",
"KOCU4839231",
"KOCU4904240",
"KOCU5067657",
"KOCU5082841",
"ROEU8622402",
"TGBU6353192"
],
"last_updated": "2025-03-28 04:09"
}
}
Whether you’re handling a few shipments or running a fast-growing logistics platform, tracking by Master B/L with JsonCargo takes the guesswork out of where your cargo really is. Even if container numbers aren’t available yet, you’ll still have visibility from day one.
With JsonCargo, you get:
Coverage of more than 95% of the Shipping Lines
Free updates in the API and conducts regular checks to ensure good data quality
Simple API integration
Common Questions About Container Tracking Data via API:
Q1: Can I track shipments with JsonCargo even if I don’t have the container number yet?
Yes. That’s the main advantage of using the Master Bill of Lading. JsonCargo lets you begin tracking as soon as the carrier issues the MBL, often days before container numbers appear in EDI systems.
Q2: Does JsonCargo work with all carriers?
JsonCargo integrates both carrier data feeds and AIS vessel tracking, which means you can track shipments across all major shipping lines worldwide, and you can check the covered Shipping Lines.
Q3: Is JsonCargo only for large enterprises?
No. JsonCargo is designed for both small and large businesses. Startups, retailers, freight forwarders, and manufacturers all use JsonCargo because the API is simple to integrate into existing workflows.
Q4: How do I start using JsonCargo?
Just get an API key, make your first call with a Master B/L number, and you’ll instantly see containers assigned in real time.