What nobody tells you before you replatform
Most brands that replatform are surprised by the same things.
Not the cost of the build — they expected that — but everything else.
The internal disruption. The features that didn't make the cut. The problem that was there before and remains, just on newer infrastructure.
What replatforming actually involves
A replatform is not a website rebuild. It is a structured migration of your commercial infrastructure. Product data, pricing logic, integrations, order history, and URLs all move from one system to another while the business continues to trade.
The platform decision (Shopify, BigCommerce, or something else) is typically the smallest part of the work.
What takes time, money, and internal resources is everything around it.
What the agency proposal won't include
Agency proposals cover what the agency controls. They do not cover what you control — and the gap between those two things is where most replatform pain lives.
Internal time
The highest invisible cost. Someone in your business will need to own this project: briefing the agency, reviewing work, managing stakeholders, and QA-ing output across devices and browsers. For most projects with more than two or three integrations, that is a near-full-time responsibility for the duration of the project. If you do not have that capacity, either the project slows down or the output suffers.
Training and adoption
Rarely appears in project plans. Your team will need to operate the new platform. If the switch happens at pace with minimal documentation, you absorb operational inefficiency post-launch that takes weeks or months to work through.
The Phase 2 list
Every replatform produces a Phase 2 list at go-live. Features deprioritised to hit a launch date. Customisations that were technically complex and got pushed. Integrations that weren't ready in time.
Most Phase 2 lists never get built. This is not a failure of intent — it is structural. Once the new platform is live, the energy that drove the project dissipates. Internal bandwidth returns to trading. Phase 2 becomes the backlog.
Where does the time go?
Timeline slippage on ecommerce projects follows predictable patterns. Discovery findings surface complexity that wasn't in the original brief. Data migration takes longer than scoped. A key integration is underdocumented, and the third party is slow to respond. QA surfaces issues that require rework in design and development. A stakeholder changes their mind about a feature.
These are the standard conditions of a project with real complexity. The timeline in a proposal assumes clean inputs, fast decisions, and no surprises. Real projects rarely provide any of those.
If you are planning around a specific go-live date — a trading peak, a budget cycle, a board commitment — build in a healthy buffer.
The original problem usually survives the migration
This is the one that costs brands the most and gets discussed the least.
Replatforming is commonly proposed as a solution to a growth plateau, conversion problems, or operational friction. Sometimes it is the right solution. Often, it is the most visible action available — and visibility gets confused with relevance.
If the conversion rate is low because the product pages are unclear and the checkout experience is clunky, a new platform will help. If the conversion rate is low because the product-market fit is weak, the pricing is off, or the traffic mix is wrong, a new platform changes nothing except the theme and the monthly bill.
If operational friction exists because the team lacks process and ownership is unclear, a new platform adds a new set of tools to the same operational environment. The friction simply moves.
The brands that get the least from replatforming are the ones that went in with an incomplete diagnosis and assumed the platform would do more work than it can. Six months post-launch, they are on newer infrastructure with the same plateau — and no clearer on why.
The 3-year commercial picture
A replatform is not a one-time cost. It commits you to a cost base and a development model for the next several years.
Platform licence fees change. Shopify and BigCommerce have both revised pricing and moved features between tiers. What you pay at launch may not be what you pay in year three. Build this into your model.
Development dependency shifts. The platform choice affects your ongoing cost-per-change and your dependency on external resources.
Technical debt accrues on new platforms, too. Customisations made at pace to meet a deadline, apps added to plug gaps, and integrations that were never documented all compound. Before you commit, ask: do we have the internal discipline and development resource to maintain this platform properly post-launch, or are we likely to repeat the same patterns that made the current one feel constrained?
The question is not just "what does this cost to build" but "what does this cost to operate and evolve over three years, against what it would cost to stay and improve what we have."
How to decide whether replatforming is actually the right answer
The questions worth answering before you commit:
Is the platform actually the constraint?
Not the interface, not the speed, not the appearance — but the underlying capability. List the specific things your current platform prevents you from doing that would materially affect revenue or operational cost. If the list is short or unclear, the platform may not be the constraint.
What happens if you stay and invest instead?
Model the cost of staying on your current platform and allocate the replatforming budget to conversion improvements, operational tooling, and the development of missing features. For some businesses, this is worse than migrating. For others, it is materially better.
Is your team ready to absorb this?
A replatform during a period of operational instability, rapid headcount changes, or a senior team transition carries a significantly higher risk of failure. Readiness is a factor in timing, not just capability.
What does the post-launch operating model look like?
Who maintains the platform? Who owns development decisions? Who manages the agency relationship? If these are not answered before the project starts, you will improvise the answers later.
Who internally needs to agree — and do they?
Platform decisions often involve a technology lead, a marketing director, and a finance director with different priorities and different tolerances for disruption.
What good pre-replatform diagnostic work looks like
Before a credible replatform scope can be produced, certain things need to be understood. Which integrations are load-bearing and which are legacy. Where the actual conversion drop-off occurs and why. Whether the commercial case for migration holds up when tested properly.
This is not what a standard agency discovery covers. Most agency discovery is scoped to produce a project brief, not to challenge whether the project is the right one.
Strawberry's Clarity engagement is structured diagnostic work. It covers platform suitability and integration mapping, and tests whether the business case holds up before you commit capital. The diagnostic costs less than finding out the hard way.
If you are at the point where replatforming feels likely, but you have not yet formally scoped the work, Clarity is the appropriate next step.
Shopify vs BigCommerce: does the platform choice matter?
Yes — but less than most brands think, and at a different stage than the conversation usually happens.
Shopify's ecosystem is broader — more apps, a deeper developer pool, and a faster path from brief to build. For brands with standard integration requirements and a preference for speed, it is the lower-friction choice.
BigCommerce offers more native flexibility without customisation. Complex pricing rules, multi-storefront requirements, and B2B functionality are often better supported. For brands whose requirements push against Shopify's boundaries, BigCommerce often removes constraints that would otherwise require expensive custom development.
The platform decision should follow the requirements assessment, not precede it. Choosing a platform before you understand your actual integration requirements is how brands end up constrained again eighteen months after launch.
Replatforming is frequently the right answer
Platforms do constrain growth. Legacy infrastructure does create operational drag that no amount of tooling around it will fully resolve. The cost of staying can exceed the cost of moving.
The brands that get the most from replatforming are clear on what they are solving and what it will actually cost in total. The third thing — what they are not asking the platform to fix — is the one most get wrong. They only discover what they expected the platform to do for them once it hasn't.
Frequently asked questions
How long does an ecommerce replatform take?
For a brand doing £1m–£10m in revenue with moderate integration complexity, a twelve- to twenty-week-scoped timeline is common. Complexity determines the actual answer more than any benchmark.
What does an ecommerce replatform cost?
Build cost varies significantly by platform, agency, and scope. A Shopify migration for a brand with standard complexity typically ranges from £25,000 to £80,000+. BigCommerce projects with similar custom integrations are in a similar ballpark. These figures cover build only — internal time, third-party integrations, and post-launch development are additional.
What are the biggest risks in an ecommerce replatform?
Underdiagnosis at the start is the biggest one — it causes most of what follows. After that: integrations that are more complex than scoped, data migration issues that surface late, SEO impact from redirect errors, and a team that wasn't resourced for post-launch.
Should I replatform to Shopify or BigCommerce?
Maybe. It depends on your integration requirements, customisation needs, and growth trajectory. The decision should follow a proper requirements assessment, not precede it.
What is the difference between a replatform and a redesign?
A redesign changes the front-end: layout, visual identity, and UX. A replatform changes the underlying system. The two often happen simultaneously, which can increase complexity.
What should I do before briefing a replatforming agency?
Understand what problem you are actually solving. Map your integrations — which are business-critical, which are legacy, which are underdocumented. Assess your data quality. Then decide who will own the project internally and confirm that replatforming is the highest-leverage move available to you right now.
