What it does

For stores that print their labels in ShipStation (USPS, UPS, FedEx, DHL, Canada Post, Australia Post, Royal Mail and every other carrier you connect there). The add-on gives your store a secure Custom Store endpoint: you paste its address, username and password into ShipStation, and no ShipStation API keys are needed. You use your own ShipStation account. Multi-Vendor: one ShipStation store for the marketplace or one per vendor; Ultimate: one per storefront.

How it works

Generate the endpoint credentials in CS-Cart, choose the ShipStation group for each order status, then add a Custom Store in ShipStation with the URL, username, password and five status words. ShipStation imports orders page by page. When you create a label, the add-on creates the shipment, ships part or all of the order and sets your shipped status. ShipStation is a trademark of its owner; this add-on is not affiliated with or endorsed by ShipStation.

Features

Custom Store endpoint with Basic authentication, encrypted password and constant-time checks
Order import with paging, items, options, images, weights, discounts, notes, payment and shipping method
Order status map to ShipStation's five groups, custom statuses included
Tracking numbers back as CS-Cart shipments with carrier tracking links (24 carrier families, add your own)
Partial shipments: each package becomes its own shipment, quantities matched per order line
Duplicate and parallel shipment notices never create a second shipment
Shipped and partly shipped order statuses, cancelled orders left untouched
Choose whether CS-Cart or ShipStation e-mails the customer
Log with filters and CSV export, retry queue for notices that could not be applied at once
Multi-Vendor: marketplace ShipStation store or one per vendor with vendor privileges; Ultimate: one per storefront

What you get

Package	kv_shipstation-1.0.0.zip, installed through Add-ons → Manage add-ons
Updates & support	12 months included. Download new versions from your account and install them in Add-ons → Manage add-ons or the Upgrade Center.
License	1 production installation. Staging, dev and localhost are free and unlimited. The add-on keeps working after the update period ends. How licensing works

Compatibility

We list only the builds we install and test on. “Tested” means the full test plan was run on that build; “Supported” means the build is inside the supported range and uses the same hooks.

CS-Cart version and edition compatibility
CS-Cart version	CS-Cart	CS-Cart Ultimate	Multi-Vendor	Multi-Vendor Ultimate
4.22 and later	Testing next	Testing next	Testing next	Testing next
4.21.2	Supported	Supported	Supported	Supported
4.20.x	Supported	Supported	Supported	Supported
4.19.x	Supported	Supported	Supported	Supported
4.18.x	Supported	Supported	Supported	Supported
4.17.2	Supported	Supported	Tested	Supported
Before 4.17.2	Not supported	Not supported	Not supported	Not supported

Last tested build: Multi-Vendor 4.17.2, Nov 8, 2026Tested on: Multi-Vendor 4.17.2

Requirements

Platform	CS-Cart or Multi-Vendor 4.17.2 to 4.21.x
Requirement	The storefront must answer over HTTPS from the internet (ShipStation calls your store). A maintenance page, a password-protected staging site or a firewall that blocks ShipStation's servers stops the import
PHP	The web server must pass the `Authorization` header to PHP (see Troubleshooting if ShipStation reports a login error although the password is right)
Requirement	A cron job is recommended for the retry queue (see Configuration)
Core changes	None. Hooks and template overrides only

1.0.0

Nov 8, 2026

Latest

Added 7

ShipStation Custom Store endpoint (action=export and action=shipnotify) with Basic authentication, encrypted password, constant-time checks and generated credentials shown once.
Order export with paging, a modified-between window (with overlap), items with options, images and weights, discount line, notes, payment and shipping method; every field cut to ShipStation's documented length (multibyte safe).
Order status map from every CS-Cart status to ShipStation's five groups (or not sent).
Shipment notices become CS-Cart shipments with carrier tracking links (24 carrier families, custom links per carrier); partial shipments matched per order line; shipped / partly shipped order statuses; cancelled orders untouched.
Idempotent notices: one shipment per tracking number, also for parallel duplicates (unique key, per-order lock, adoption of an existing shipment).
Multi-Vendor: marketplace store or one ShipStation store per vendor with vendor privileges per action; CS-Cart Ultimate: one per storefront.
Log with filters and CSV export, retry queue with back-off, cron (command line and secret URL), upgrade synchronizer and licence client.

Tested on Multi-Vendor 4.17.2. First release.

Which ShipStation plan do I need?

The add-on uses ShipStation's Custom Store connection, which ShipStation documents without a plan limit. It does not use the ShipStation API keys, which ShipStation reserves for Standard / Accelerate plans and higher.

Do I need API keys?

No. You create a username and password in CS-Cart and type them into ShipStation's Custom Store form.

Does it show ShipStation rates at checkout?

No. Checkout keeps your CS-Cart shipping methods. Labels are bought in ShipStation.

Which carriers work?

Every carrier you connect in ShipStation. The add-on shows tracking links for 24 carrier families out of the box (USPS, UPS, FedEx, DHL, Canada Post, Australia Post, Royal Mail, Evri and more) and you can add a link for any other carrier.

What happens when one order ships in several boxes?

Each label becomes its own CS-Cart shipment with the items of that box. The order gets your "shipped" status after the last item.

What if ShipStation sends the same notice twice?

Nothing: one tracking number gives one shipment, also when the notices arrive at the same time.

Can each vendor use their own ShipStation account?

Yes. Switch off Marketplace owner mode; each vendor then sets up a Custom Store with their own credentials in the vendor panel and sees only their own orders. Vendors without their own store keep going to the marketplace store.

I have several storefronts (CS-Cart Ultimate).

Each storefront has its own endpoint and credentials; connect each as a separate Custom Store in ShipStation.

What happens to the tracking links if I switch the add-on off?

The CS-Cart shipments stay, but CS-Cart shows them without the carrier name and link while the add-on is disabled or uninstalled. Keep it enabled as long as customers may open older orders.

Is the password safe?

It is stored encrypted, compared in constant time, never shown again and never written to the log. Use HTTPS for the endpoint.

Does it work with full page cache, Smarty 5, PHP 8.3?

Yes: the endpoint is never cached, the add-on has no storefront output, and it runs on CS-Cart 4.17.2 to 4.21.x with PHP 7.4 to 8.3.