Short answer: Black Friday site readiness is seven jobs: a load test that covers the real cart and checkout flow, caching and a CDN for static files, a second payment path, faster stock sync, a speed budget for the campaign page, a code freeze on November 20 and a written communication plan for the moment of an outage. The aim is not to grow traffic but to stop the visitor your ad brought from getting lost at the payment step.
Which infrastructure jobs should you do before Black Friday?
Site infrastructure readiness comes down to seven jobs: load testing, caching and CDN, payment backup, stock sync, campaign page speed, code freeze and an outage plan. However well you split the ad budget, a site whose payment step does not respond wastes that budget. We cover the calendar and the budget side in our Black Friday 2026 e-commerce plan and review them in the free November Readiness Audit, and the settings inside the ad platforms are in our guide to Google Ads and Meta settings for Black Friday week. This article covers only the technical side.
Black Friday also goes by local campaign names in some markets, and in many of them the sale season covers the whole month. From an infrastructure point of view two days stand out. 11.11 on November 11 is the first peak and the first real test of your system, and November 27 is the main peak. Set aside November 12-19 to close the bottlenecks you see on 11.11 before November 27. The first peak is covered in our Singles' Day 11.11 guide.
| Date | Job | Output |
|---|---|---|
| October 29-November 4 | Writing the load test scenario and a first run | A bottleneck list with an owner and a date for each item |
| November 5-9 | Fixes for caching, CDN and payment backup | A corrected environment and a test order |
| November 10 | Code freeze for 11.11 | A written freeze announcement |
| November 11 | Live monitoring | An hourly note on errors and payment completion |
| November 12-19 | Closing the 11.11 findings and a second load test | An updated bottleneck list |
| November 20 | Code freeze for Black Friday | A written freeze announcement |
| November 27-30 | Live monitoring and keeping the outage plan ready | An incident log |
| December 1 | Lifting the freeze | A rollback and cleanup list |
How do you run a site load test?
A load test means measuring in advance whether your site keeps responding under a given number of simultaneous users. Test the real customer journey and not the home page: the campaign page, the product page, add to cart, the payment step and the order confirmation. The home page can be served from cache, while the cart and payment step need server processing for every user. That is where the real load builds up.
When you estimate target traffic, consider last year's peak hour, your 11.11 results and the extra visitors your planned ad budget will bring. Set the test target above that estimate and raise the load gradually and not all at once. Run the test on a copy of the live system and do not put load on the live site. Track the error rate, the response time and the completion rate of the payment step separately. List every bottleneck the test finds with an owner and a date.
A test is not done once and forgotten. Because 11.11 gives real traffic data, run the second round between November 12 and 19 with that data.
What do caching and a CDN solve on Black Friday?
Caching and a CDN reduce server load by serving a ready copy of a file instead of rebuilding it on the server for every visitor. According to web.dev's CDN guide, static content such as images, video and versioned libraries can be cached for a long time. For a CDN to cache a resource, at least one of the Cache-Control: max-age, Cache-Control: s-maxage or Expires headers generally has to be set.
Cart, checkout and account pages are personal to each user. According to web.dev, Cache-Control: private is used for personalized responses, and intermediate caches do not store them. A misconfigured CDN that shows one user another user's cart is more expensive than a load problem. Verify the rule with a real test order.
For content that changes often, such as campaign prices and stock, keep the cache lifetime short or purge the cache at the moment of the update. For content that changes at an unpredictable rate, web.dev lists caching for a long time and purging when the content is updated as one option. For the other speed steps, see our site speed and Core Web Vitals guide.
Which backups should you prepare for the payment infrastructure?
Prepare three backups for payments: a second payment path, a tested 3D Secure flow and a peak-day contact channel with your payment provider. Ads bring the customer in and the payment step is the only place where revenue actually happens. Depending on a single provider makes that point a single point of failure.
A second payment provider or gateway exists so that an order is not lost when the first one fails. Clarify in advance whether the switch will run automatically or by hand, whether the payment method options are the same on both paths, and what the fee difference is. Try the switch together with your payment provider, with a test order, before you go live.
According to EMVCo, 3D Secure is a protocol used to authenticate the cardholder in online card payments, and for risky transactions the card issuer may ask for additional verification. This step is outside your control, and if the customer gets lost here, the payment does not complete. Try test orders with cards from different banks and on mobile, and check what the customer sees in cases such as a delayed verification code. For a simple payment form, follow the steps in our guide to reducing cart abandonment.
How do you prevent stock sync problems and overselling?
Overselling means selling a product you do not have, and it often comes from a sync delay between the website, marketplaces and the stock system. On peak day orders arrive within seconds, so even a short delay can sell the same last item on more than one channel.
Three measures work. First, do not open the full stock to every channel and set aside a part of it as a safety margin. Second, shorten the sync interval for peak day and monitor the delay. Third, test that a product closes automatically on the site and in the ad feed when stock reaches zero. For the stock split between marketplaces and your own site, see marketplace or your own website.
If overselling does happen, write to the customer as early as possible with the reason and the options. Cancelling silently brings reviews and complaints. Prepare the cancellation and notification text in advance.
Which thresholds measure campaign page speed?
Campaign page speed is measured with Google's Core Web Vitals thresholds: LCP should be under 2.5 seconds, INP under 200 milliseconds and CLS under 0.1. Measurement is taken at the 75th percentile of page loads, separately for mobile and desktop.
In November the campaign page is the page that gets the most ad traffic on your site, so set a speed budget just for it. Do not put unoptimized high-resolution images, heavy video or many third-party scripts on the page. Place the countdown and the campaign banner so that they do not shift the content after the page loads. Take the last measurement before the freeze on a real mobile device.
When should the code freeze date be?
A code freeze means stopping new features and changes from going to the live system after a certain date. Setting the Black Friday freeze for the evening of Friday, November 20 leaves a one-week safety margin before November 27. For 11.11 the same logic gives November 10.
During the freeze only critical bug fixes go through, and each one has an approver, a rollback plan and a test record. Content jobs such as campaign prices, stock and text updates stay outside the freeze, but under a simple rule: they are done from the admin panel and need no code. Announce the freeze to the team in writing and lift it on December 1.
What should you do if the site goes down?
The first minutes of an outage should be written down in advance, because deciding in a crisis wastes time. If ads keep running while the site is down, budget is wasted. So the first item of the plan is who pauses the ads and on which symptom.
The status code of the page served during an outage matters too. According to Google's documentation, if you have to take the site offline for 1-2 days, it recommends serving the information page with a 503 status code and stating the time to retry with a Retry-After header. Google treats 503 and 429 responses as server errors and slows crawling. URLs in the index are kept for a while, but if the error continues they can eventually drop out of the index, so keep the outage short. For measurement problems on the ad side, see the data exclusion section of our guide to Google Ads and Meta settings.
The outage plan should answer at least these five questions in writing:
- Owner: is the person who runs the incident, and their backup, named?
- Decision: who decides to pause the ads, and on which symptom?
- Customer communication: is there ready text for the maintenance page, social media and customer service?
- External contacts: do you have the emergency contacts of your payment provider and your hosting company?
- Recovery: is there a plan to turn the ads back on and to send reminders to carts left half done once the problem is solved?
Which indicators should you watch on peak day?
On peak day watch six indicators on the same screen: orders per minute, payment step completion rate, server response time, error rate, stock sync delay and the ratio of ad spend to order flow. When one of them degrades, it warns you before the others. Write the thresholds in advance, for example who calls whom when the payment completion rate falls below a normal day. Verify with a test order that your measurement tags work correctly, otherwise you can stop a campaign by mistake because no orders appear in the dashboard.
Frequently asked questions
When should I run a site load test before Black Friday?
Run the first round before 11.11 and the second between November 12 and 19 with the 11.11 data. Test the real customer journey with the campaign page, cart and payment step and not the home page, set the target above last year's peak hour and run the test on a copy of the live system.
When should the code freeze start?
We recommend the evening of Friday, November 20 for Black Friday and November 10 for 11.11. During the freeze only critical bug fixes go through, each with an approval, a rollback plan and a test record. Lift the freeze on December 1.
What status code should the error page return if the site goes down?
If the outage is temporary, return 503. According to Google's documentation, for a 1-2 day outage the information page is served with a 503 status code and a Retry-After header can state the time to retry. Google treats 503 and 429 responses as server errors, and if the error continues, URLs in the index can eventually drop out.
Should a CDN cache cart and checkout pages on Black Friday?
No. Cart, checkout and account pages are personal to each user and should be kept out of intermediate caches with Cache-Control: private. What you cache are static files such as images, CSS and JavaScript. Verify the rule with a test order.
Is a second payment path really needed?
Because the payment step is the only place where revenue happens, depending on a single provider creates a single point of failure. A second payment provider or gateway prevents an order from being lost when the first one fails. Settle in advance whether the switch is automatic or manual, which payment method options each path offers and what the fee difference is.
How do you prevent overselling?
Do not open the full stock to every channel and set aside a part of it as a safety margin. Shorten the sync interval for peak day and test that a product closes automatically on the site and in the ad feed when stock reaches zero. If overselling happens, write to the customer early with the reason and the options.
Related articles
- Black Friday 2026 Plan: Four Sales Waves for Your Online Store
- Free November Readiness Audit for Black Friday
- How to Set Up Google Ads and Meta Campaigns for Black Friday Week
- Site speed and Core Web Vitals guide
- How to reduce cart abandonment
- Marketplace or your own website
- Singles' Day 11.11 2026: An E-Commerce Preparation Guide
Let's see together whether your site is ready for the peak. In the free November Readiness Audit, site speed and Core Web Vitals and your cart and checkout flow are among the eight areas.
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