The Fulfillment Bolt brings shipping label generation directly into your CartOS admin. Purchase discounted labels from major carriers, print them instantly, and automatically send tracking information to customers—all without leaving your order page.
How it works
The Fulfillment Bolt connects to EasyPost, a shipping API that aggregates rates from dozens of carriers. When you create a shipping label, EasyPost fetches real-time rates from all available carriers and presents them in one place. You pick the best option, purchase the label, and print it.
Labels purchased through EasyPost often come with significant discounts compared to retail rates, especially for USPS services. You don't need your own carrier accounts to get started—EasyPost provides default access to most major carriers.
Installing the Fulfillment Bolt
Go to Bolts in your admin dashboard and find the Fulfillment Bolt. Click Install to add it to your store. Once installed, you'll see a new Fulfillment section in your admin sidebar and shipping options on your order pages.
Connecting EasyPost
To use the Fulfillment Bolt, you'll need an EasyPost account. If you don't have one, visit easypost.com to sign up—it's free to create an account and you only pay when you purchase labels.
Once you have an EasyPost account, grab your API key from your EasyPost dashboard. In CartOS, go to Fulfillment › Settings and paste your API key in the EasyPost API Key field. Click Save to connect.
CartOS will verify the connection. Once confirmed, you're ready to start creating labels.
Setting your ship-from address
Before creating labels, configure your ship-from address in Fulfillment › Settings. This is the return address that appears on your labels and is used to calculate shipping rates. Make sure it's accurate—carriers validate addresses and incorrect information can cause label purchases to fail.
Configuring package defaults
Set up default package dimensions to speed up label creation. Go to Fulfillment › Packages to create package presets for your common box sizes.
For each package, enter a name (like "Small Box" or "Padded Envelope"), the dimensions (length, width, height), and an optional default weight. When creating a label, you can select from your saved packages instead of entering dimensions manually every time.
Connecting your own carrier accounts
While EasyPost provides access to carriers with built-in discounts, you can also connect your own carrier accounts if you have negotiated rates. This is common for high-volume shippers who have contracted rates with UPS, FedEx, or other carriers.
To add a carrier account, go to your EasyPost dashboard and navigate to Carrier Accounts. Follow the instructions to connect each carrier using your account credentials. Once connected in EasyPost, those rates will automatically appear when creating labels in CartOS.
Supported carriers
Through EasyPost, the Fulfillment Bolt supports a wide range of carriers including:
- USPS – Priority Mail, First-Class, Ground Advantage, Media Mail, and more
- UPS – Ground, 2nd Day Air, Next Day Air, and international services
- FedEx – Ground, Express, Home Delivery, and international services
- DHL – Express and eCommerce services
- Regional carriers – OnTrac, LSO, Spee-Dee, and others depending on your location
Available services depend on the origin address, destination, and package characteristics. The Fulfillment Bolt automatically shows only the services that are valid for each shipment.
Creating a shipping label
Open any unfulfilled order and click Create Shipping Label. The shipping panel will open, showing the destination address and allowing you to configure the shipment.
First, verify or edit the package details—select a saved package preset or enter custom dimensions and weight. Accurate weight is important since carriers charge by dimensional or actual weight, whichever is greater.
Click Get Rates to fetch available shipping options. You'll see a list of carriers and services sorted by price, with estimated delivery dates for each. Select the option you want and click Purchase Label.
The label is generated immediately. You can print it directly from your browser or download the PDF to print later. The order is automatically marked as fulfilled and the customer receives a shipping confirmation email with the tracking number.
Batch label creation
For high-volume days, you can create labels for multiple orders at once. Go to Orders, select the orders you want to fulfill using the checkboxes, and click Create Labels from the bulk actions menu.
You'll be prompted to confirm package details for each order. Once confirmed, all labels are purchased and generated together. Download them as a single PDF for easy batch printing.
Voiding labels
If you've purchased a label but haven't used it, you can void it for a refund. Open the order, find the label in the fulfillment section, and click Void Label. Most carriers allow voiding within a certain window (typically 14-30 days). Refunds are credited back to your EasyPost account balance.
Tracking and delivery updates
Once a label is created, tracking information is automatically saved to the order. CartOS periodically checks for tracking updates through EasyPost and logs delivery events in the order timeline.
Customers can track their packages using the link in their shipping confirmation email, which takes them to the carrier's tracking page or your store's order status page if you've enabled order tracking.
Troubleshooting
If label creation fails, the most common causes are address validation errors or missing package information. EasyPost validates addresses before generating labels—if the destination address can't be verified, you'll see an error. Double-check the address for typos, missing apartment numbers, or invalid postal codes.
For rate fetch failures, make sure your EasyPost API key is correct and your account is in good standing. Some carriers may also be temporarily unavailable; try again in a few minutes or select a different carrier.