Costco UK
Complete guide on our Costco UK module
Our Costco module supports account-based checkout and is designed to handle both API and frontend monitoring, multiple queue entry attempts, and standard add-to-cart flows. Costco UK often uses queues, strict cart validation, and fast sellouts, but Stellar streamlines the process with session-based logins, watch task pairing, and optional queue farm setups. This module performs best for high-demand products, hot electronics, limited drops, and products known to appear with little warning.
Quick Start (Recommended Setup)
Add your Costco UK session under Identities → Sessions.
Make sure your Costco UK account has a default UK shipping address as well as a Default Payment saved.
Create profiles MATCHING address and payment information that you saved to your account, otherwise payment errors will occur.
Run:
1 Monitor task per product
1 Normal mode checkout task per account
Clear your Costco cart before starting tasks.
If the product uses a Queue-It system, our tasks can sometimes pass this by restarting tasks and ATC’ing product whilst everyone waits, otherwise, wait for task to pass queue.
Use UK ISPs, DCs, or residential proxies depending on your setup.
Keep checkout delay low (around 3000 ms).
Preliminary Checklist
Before setting up tasks on Costco UK, make sure you have everything below prepared:
Profiles
Accounts are required for checkout.
Account email must match the profile email.
Make sure a default UK shipping address and Payment Information match details inside your Costco account.
Proxies
ISP proxies – Recommended for some of your tasks (ensure they are UK-located).
Residential proxies – Recommended for the majority of your tasks.
Save both proxy groups under the Proxies tab in Stellar.
If you're looking for proxies, check out Stella Proxies for high-quality ISP and Residential proxies.
Costco Accounts
Accounts are required for checkout.
Account email must match the profile email.
Make sure your default shipping address and Payment Information is saved inside your Costco UK account.
Cook Group Access
Optional but recommended. Your UK cook group can help you find product URLs, item numbers/SKUs, and early restock alerts.
Test Task
Before big drops, run a test task on a random in-stock product to confirm your account, proxies, and delays are functioning correctly.
Sessions & Login
Go to the Sessions tab.
Click on Add Session.
Enter:
Session Name
Email (Costco UK account email)
Password (Costco UK account password)
Click Save.
The session logs in automatically when starting a Normal mode task.
Task Strategy & Timing
How Many Monitor Tasks Should I Create?
Run 1 Monitor task per SKU.
You can run multiple Monitor tasks if you want redundancy, but it’s not required and usually unnecessary.
Monitor tasks are lightweight and can run 24/7.
Recommended: 1 Monitor task per SKU is sufficient for most users.
How Many Checkout Tasks Per Account?
Strictly 1 checkout task for each SKU per Costco account.
Running more than one checkout task on the same account can cause:
Checkout failures
Login/session instability
Basket instability
Rule: 1 account = 1 checkout task (no exceptions).
Task Overview
Normal Mode
Monitor Mode
When to Use Modes
Important: Your Costco account logs in when tasks start, not when the session is created. Always clear your cart manually before running tasks.
Normal Mode (Checkout Mode)
Standard checkout flow.
Logs in → ATC → checkout.
Uses session credentials.
Best for direct restocks and fast-moving items.
Monitor Mode
Monitors the product.
Pings any checkout task with Watch Task enabled.
Does not add to cart or checkout.
Unlimited number of monitor tasks allowed.
Task Fields Config
Profile
Select the profile you want to use for checkout.
You may use:
ISP (UK region preferred)
DC
Residentials
If you're looking for proxies, check out Stella Proxies for high-quality ISP and Residential proxies.
Product URL
Find the product on Costco UK and copy the SKU found in the URL.
Example: www.costco.co.uk/Toys-Baby-Child/Toys-Games/Collectables/Pokemon-TCG-Mega-Charizard-X-ex-Ultra-Premium-Collection-6-Years/p/1930406
SKU is = 1930406, sometimes there may be an item variant – you’ll see this as a drop down on the product page, select the variant you want and the URL will update, e.g. to 1930406A – this would be the SKU to run.
Paste this into your task’s SKU field. Your cook group will provide exact product SKU’s.
Monitor
Delays
Recommended:
Monitor Delay: ~5000 ms
Reset Delay: ~5000 ms
Adjust based on your proxies and cook group guidance.
Quantity (QTY)
Check with your cook group for product-specific quantity rules.
Stellar does not auto-adjust if you set the quantity too high.
Session
Allows you to pick which Costco UK session to use for the task.
Login Method
Costco is known for frequently temp-banning or flagging accounts, which can interrupt task flow. To help with this, Stellar supports Passcode (OTP) Login, allowing you to fetch the verification code through IMAP or Manual Input.
Endless Mode
ON → Your task will continue to checkout until defined about in ‘Endless Limit’. Please note, this does not bypass any item limits placed by Costco UK.
OFF → Your task will stop after logged checkout.
Watch Task
Helps reduce proxy bans and improve speed.
If enabled:
Checkout task waits for the Monitor task.
Monitor task pings the checkout task when the product is in stock.
Checkout task immediately starts ATC + checkout.
If disabled:
Checkout task monitors, ATCs, and checkouts independently.
Higher request load.
Disable Watch Task if the product is using a queue system.
Common Errors and Fixes
Akamai Ban
Cause: Account- or proxy-related issue.
Fix: Try different proxies or reset your Costco account password.
Kasada Ban
Cause: Account- or proxy-related issue.
Fix: Try different proxies or reset your Costco account password.
Waiting For Monitor
Cause: Normal status message.
Fix: Task is waiting for a monitor-mode task or server-side monitor. It will proceed once the product is detected in stock.
Costco UK Drop FAQ
Do I use residential proxies or ISPs?
Use a mix of both UK-based providers and see what performs better for your specific setup.
Is it one account per task?
Yes. Strictly one account per task. Using multiple tasks on one account can cause instability of item carts.
“adding to cart - akamai ban”
Proxy block. Try different providers—ideally residential proxies.
“initiating checkout - akamai ban”
Account temporary block or proxy block. Try running tasks with Stop Task After Carting enabled and check out manually. If you see ERR_HTTP2_PROTOCOL_ERROR or “Costco mobile services unavailable”, it’s a 100% account block. Let the account rest for a while.
“error submitting order - server error”
Caused by profile issues or Costco itself. We push regular updates to improve handling of this error, but if it’s profile-related (e.g., mismatch or incorrect payment format) it may not be solvable by the bot. Test your profile on a cheap in-stock item: if it works, it’s site-related and due to high traffic load.
“handling cart 400 = INVALID PRODUCT CODE”
Item has a variant – you’ll see this as a drop down on the product page, select the variant you want and the URL will update, e.g. to 1930406A – this would be the SKU to run, your Cookgroup will also provide this too.
“out of stock”
Can be in relation to account, e.g. limit of account has been hit for specific product.
“payment declined”
Check your account manually and attempt to pay, item will be added to cart.
Additional Note – if having any payment issues, however item shows ‘Added to Cart’ – please manually check your account and attempt checkout, sometimes profile isn’t set properly, however this carting could be the difference between you securing stock or nothing.
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