This page is written for operators who have already decided Shopify is plausible and now need to figure out scope, sequencing, and partner selection. It is not a Shopify Plus sales pitch and it is not a cheerleader piece for any single migration agency. The patterns below come from brands that have run this play already.
Throughout, we use specific dollar ranges and week ranges. They reflect typical 2025-2026 engagements at the $5M-$200M brand size. If your situation is far from the median — sub-$5M, post-$200M, complex B2B, headless — the ranges shift but the decisions do not.
When replatforming is the actual decision
Operators conflate three different decisions in the same conversation: replatform, rebuild on the same platform, and re-architect downstream systems. They are separate. Treat them separately.
Replatforming is the right framing when the storefront platform is the dominant constraint — checkout limitations, app-ecosystem mismatch, headless cost-to-serve, or operator hours spent fighting the CMS rather than running the business. If the constraint is your warehouse, your finance stack, or your data model, replatforming will not fix it and may make it worse.
The cheapest move at this stage is a 30-minute call with someone who has shipped this migration before. They will tell you within that call whether you have a Shopify problem or an ERP problem disguised as a Shopify problem.
Typical scope, cost, and timeline ranges
A full replatforming engagement for a $5M-$50M DTC brand typically runs $60K-$220K in agency fees and 14-26 weeks elapsed. The wide range is real, not hedging — the variables are SKU count, custom-field complexity, subscription tenure, app dependency count, and whether content (blogs, landing pages, metafields) is in scope.
Inside that, expect three to five line items: data migration, theme rebuild, app re-implementation, SEO migration audit, and post-go-live optimization. Brands that ship cleanly almost always pay separately for SEO migration — the platform-default redirect mapping is not enough when the URL structure is genuinely changing.
The cost most operators underestimate is internal. Two to four hours per week from a product owner, the ecommerce lead, and someone on finance, for the full duration. If you cannot free those hours, scope the engagement smaller or push the timeline out.
Choosing a partner versus running internally
Below $10M and with an existing in-house developer, an internal-led replatforming is feasible — and usually slower than expected by a factor of two. Most brands underprice the SEO and data-quality work, which then surfaces in week 8 as a crisis that resets the timeline.
Partner-led is the default at $10M+. The question is not whether to bring in a partner; it is which partner shape — a full-service replatforming agency, a Shopify Plus partner with a migration practice, or a boutique data-migration shop paired with an in-house front-end team. Each shape fits a different complexity profile.
Reference checks matter more than capability decks. Ask for two recent migrations at your revenue size, one that went smoothly and one that did not. Talk to both. The patterns the partner names in the second conversation tell you more than the capability deck ever will.
Failure modes that show up mid-migration
The recurring failure modes are surprisingly stable across engagements. SEO loss in weeks 1-8 post-launch driven by sloppy redirect mapping. Subscription churn driven by customer password resets that do not surface for two weeks. Tax data discrepancies that the finance team only catches at month-end close. Customer-service backlog from app-flow changes that nobody documented.
A specialist who has shipped the migration before will name these in the kickoff call and put mitigations in the plan. A specialist who has not will name them in the post-mortem.
The single highest-leverage thing an operator can do before signing the engagement is to ask the partner to walk through their last migration's incident log. The shape of the answer — written, specific, owned by named people — is the signal.
What the first 30 days look like
A well-run replatforming engagement opens with two to three weeks of discovery before any code is written. The deliverables of discovery are a redirect map, a data dictionary mapping every field on the source platform to its Shopify analogue (or its disposition), an app re-implementation plan, and a go-live runbook with rollback steps.
If a partner pushes to start building in week one, that is a warning sign. The platform-build work is the predictable part of replatforming. Discovery is where outcomes are determined.
Operators who succeed at this stage treat the discovery deliverables as the contract. Anything that surfaces after discovery and is not in the deliverables triggers a change order, scoped against the same baseline. That discipline is the single largest determinant of whether the migration ships on time.