Ecommerce Replatforming Checklist: Migrate Without Losing Orders, Data, or Rankings

Most stores don't replatform because they want a new website. They replatform because the old one has started to say no: it slows down at peak, it can't add a sales channel, or every change breaks something else.

That is a common story in published ecommerce case studies. Across the 87 we reviewed from software firms, 12 describe replacing a legacy platform. The ones that explain the migration in detail share a pattern: they treated the move as a data project with a website attached.

This checklist covers how to plan a migration, rehearse it, and switch over without losing orders, customer history, or search rankings.

Signs It Is Time to Move

If only one of these is true, fixing the current platform may be cheaper. If several are, start planning.

Step 1: Inventory Everything the Old Platform Does

Your old store does more than you remember. List every plugin, custom feature, integration, scheduled job, email, and report. For each one, decide whether the new platform does it natively, needs an app, needs custom work, or can be retired.

One sock brand's move to a new platform shows why this matters. Its developers had to build custom solutions, including a virtual SKU system to package and market the same SKUs differently to different customers, a product bundle service for complex packs, and a custom app connecting inventory to its 3PL.

Step 2: Map Products, Customers, and Order History

Write a field-by-field map from the old data model to the new one, and expect surprises. The same sock brand's old platform represented "configurable products" in a way the new one didn't, so the team remapped each into its own product and variant combination with custom scripts.

Order history is the other trap. As that case study warns, if you simply import old orders, "you won't maintain the correct historical dates, order numbers, transactions, payments and line-items." Customers notice when their order history disappears, and so does your finance team.

Step 3: Rehearse the Migration

Never let launch day be the first full run. Script the migration and run it end to end several times on fresh copies of your data, checking counts and spot-checking records each time.

A B2B ordering marketplace in a published case study did exactly that. Its team ran "a series of test migrations, allowing the client and customers to verify that data was being transferred correctly," which let them switch "with only a few minutes of downtime." Existing customers used the new platform the next day.

Step 4: Protect Your URLs and Search Rankings

Export every URL that earns traffic: products, categories, content pages, and images. Map each one to its new address and set permanent redirects. Carry over titles, descriptions, and structured data. Done well, a migration can improve search performance. An online fastener superstore that upgraded its platform while keeping the site running, and redesigned thousands of product and content pages, reported 129% more page views and 225% more organic traffic.

Step 5: Plan a Short, Scripted Cutover

Choose a quiet week, far from your peak season. Freeze catalog edits, run the final migration, verify, switch the domain, and test a real order on every payment method. Write each step down with an owner and a way to roll back.

Step 6: Watch the Numbers Closely After Launch

Keep the project team on call for at least a few weeks. Compare daily conversion, page speed, organic traffic, and order errors against your pre-launch baseline, and fix regressions before they become habits.

Migrating Custom Code

If your store runs on custom code, the rewrite can be the biggest cost. AI-assisted tools are changing that, with people still in charge of checking the result. A large-scale ecommerce platform operator moving off an aging Microsoft codebase reported 3x faster migration speed compared to manual rewriting, a ~65% reduction in engineering effort, and 97% functional equivalence, validated through iterative testing and review.

What to Measure Before and After

By the Numbers

Across the 87 published ecommerce case studies we reviewed (59 from DTC brands and online retailers, 28 from marketplaces), better customer experience was the most commonly reported result (20 of 87), followed by revenue up (17, three of which are funding raised rather than sales) and the replacement of a legacy platform (12). More than half give no figure at all. The examples below are self-reported by the firms that published them.

Start With a Systems Review

A replatform goes faster when you know exactly what the old store does before you leave it. A systems review inventories your platform, integrations, and data, and gives you a ranked plan for the move. Explore our custom software services or read more on the Delta blog.