eCommerce platform migration checklist: 47 steps, a cost model and a vendor scorecard

A working workbook for the team actually running the migration. We cover the layers that decide whether a migration lands: who is accountable for what, what it really costs across three years, how to score vendors before the demos bias you, the data objects that cause production incidents, and how you prove afterwards that it worked.

What you get

The eleven tabs run in the order you will need them.

Before you commit

• Executive Summary. The three architecture models compared on admin autonomy, customisation depth and relative cost profile: fully hosted SaaS, custom SaaS and modular, composable and headless. None of the three is a tier. The tab shows what each asks of your team rather than ranking them, and closes with the four questions that actually decide which one you need, including the checkout question that changes your PCI obligations.
• Delivery and Accountability. Who builds it matters as much as what you build on. Nine workstreams with three-way ownership between platform vendor, implementation partner and your own team, a column for the person accountable by name, and a column for whether it is written into a contract yet. Plus the five questions to ask before you sign anything.
• Vendor RFP Scorecard. Seven weighted categories across four vendor columns, with weighted totals, a weight validation check and a leading-vendor calculation. Each category names the evidence to demand during the demo, not just the criterion to nod at. Set the weights first, because weights adjusted afterwards tend to be adjusted toward whoever demoed best.
• Three-Year TCO Model. Nine cost lines across the three models, including the two most commonly omitted: the integration layer as a recurring cost, and internal staffing overhead. Contingency you set yourself, a check that flags when licensing is dominating your model, and a year-four run rate, because the migration invoice is not the number that decides how this looks in two years.

While you run the project

• RACI Matrix. Fourteen execution streams across seven stakeholder groups, one accountable owner per milestone, and a column for that person's name with a running count of how many rows still have nobody in them. Includes the three rows teams most often leave blank and most regret: financial-state migration, multi-brand rollout order, and rollback authority.
• Replatforming Checklist. Forty-seven items across nine phases, each with technical guardrails, an owner, a priority, a due date, and somewhere to record the evidence that it was actually done.
• Progress Dashboard. Reads the checklist and updates itself. Completion overall and by phase, what is blocked, what is past its due date, what has no date set at all, and how many high-priority items are still open.
• SEO Redirect Tracker. One row per legacy URL with automatic priority scoring from organic sessions and referring domains, so the pages carrying your traffic and links get mapped and verified first. Redirect type, mapping status and post-launch validation, plus a rollup showing how much of your organic traffic is actually covered.

After you launch

• Baseline and 90-Day Scorecard. The one tab you have to start before you migrate. Capture revenue, conversion, organic sessions, indexed pages and the operational measures while the old platform is still live, then track them at thirty, sixty and ninety days. Each metric knows whether higher or lower is better, so the verdict column reads correctly without you working it out.

Two more hold it together. Start Here says what each tab is for and which cells are yours to fill in. Sources gives every external claim with its primary source and its limitations, and lists the widely circulated statistics we deliberately left out, with the reason for each.

Who it is for

Teams evaluating a platform move, building the business case, or already mid-project and wanting to pressure-test what they have missed. It assumes real complexity: an ERP, several storefronts, or one storefront that has to serve B2B contract pricing and account hierarchies alongside retail customers.

The full 47-point checklist

Every item, grouped by phase. The workbook adds owners, priorities, due dates, status tracking and the dashboard that reads them.

Phase 1: Strategy

Phase 2: Functional, B2B and B2C

Phase 3: Systems ecosystem

Phase 4: Data migration

Phase 5: SEO preservation

Phase 6: Compliance and security

Phase 7: AI and agent readiness

Phase 8: Testing and go-live

Phase 9: Post-launch

What makes it different

It covers what the standard checklists leave out.

• Gift card and store credit balances as a live financial liability, reconciled with Finance and verified on day one.
• Stored payment tokens and whether your processor supports vault-to-vault transfer, which is what breaks subscriptions at the next renewal.
• Live B2B commercial state. Open quotes, credit balances and contract price effective dates.
• Faceted and paginated URLs, the largest class of URLs an enterprise catalogue owns and the one nobody maps.
• PCI DSS SAQ eligibility, which your checkout integration pattern determines rather than your platform choice.
• Structural ceilings. Category depth, variants per product, attributes per product. Hitting one after selection means restructuring your taxonomy mid-build.
• The delivery model. Named accountability for data migration, SEO and QA, the three workstreams that fall between parties most often.
• A definition of success captured before you move, including the operational measures that say whether the move was worth making rather than merely survivable.
• A rollback plan with a named authority to trigger it.

For the full walkthrough of each phase, read the eCommerce platform migration checklist article. If you are scoping a move now, replatforming with Core dna covers how we approach it.