How do I choose between different ecommerce agencies for a platform migration and ongoing optimization?

Choosing the right ecommerce agency for a platform migration plus ongoing optimization is less about “who looks smartest” and more about “who can reduce risk and keep improving results after launch.”

Here’s a practical way to evaluate them.

1) Separate the work into two jobs

You’re really hiring for two different capabilities:

• Migration / implementation

  • Platform setup
  • Data and catalog migration
  • Theme/build
  • Integrations
  • SEO preservation
  • Testing and launch management

• Ongoing optimization

  • CRO / UX improvements
  • A/B testing
  • Merchandising and funnel improvements
  • Performance tuning
  • Analytics/reporting
  • Roadmap prioritization

Some agencies are great builders but weak at growth. Others are strong at optimization but not migrations. You want to know which one you need most, and whether one agency can truly do both.

2) Look for relevant platform experience

Ask for proof on your exact or similar stack:

• Your current platform
• Your target platform
• Payment gateway
• ERP / OMS / WMS
• PIM / DAM
• Subscription, loyalty, search, reviews, and personalization tools

Key question:

• “Have you migrated stores of our size and complexity from this platform to that one?”

Better if they can show:

• Similar catalog size
• Similar order volume
• Similar B2B/B2C/marketplace needs
• Similar internationalization, subscriptions, or custom logic

3) Review case studies for outcomes, not just screenshots

A nice redesign is not enough. Look for measurable results such as:

• Site speed improvement
• Conversion rate lift
• Revenue per visitor increase
• SEO traffic preservation or growth after migration
• Reduced checkout abandonment
• Lower bounce rate
• Improved operational efficiency

Good sign:

• They can explain what changed, why, and what the business impact was.

Red flag:

• Case studies are mostly vague, visual, or full of buzzwords with no metrics.

4) Evaluate their migration discipline

Platform migrations are where a lot of agencies overpromise. Ask about:

• Discovery and requirements gathering
• Content and URL mapping
• SEO redirect strategy
• Data migration validation
• QA process
• Launch checklist
• Rollback plan
• Post-launch monitoring

Questions to ask:

• “How do you protect SEO during a migration?”
• “How do you handle 301 redirects and canonicals?”
• “What’s your process for validating product, customer, and order data?”
• “How do you test third-party integrations before launch?”

If they don’t have a clear answer, that’s a warning sign.

5) Assess how they do optimization

For ongoing optimization, you want a partner with a repeatable process, not random ideas.

Ask:

• How do you prioritize tests and improvements?
• What data sources do you use?
• How do you decide what to test first?
• How do you measure impact?
• How often do you ship improvements?

Strong agencies usually have:

• A structured experimentation backlog
• Analytics and event tracking expertise
• UX/CRO experience
• Clear reporting cadence
• A way to connect insights to revenue

6) Make sure they can work with your internal team

The best agency is often the one that fits your operating model.

Consider:

• Do they collaborate well with in-house developers, marketers, and merchandising teams?
• Can they work with your existing tools and governance?
• Are they comfortable with your approval process?
• Do they provide PM, QA, design, dev, analytics, and strategy support?

If your team is small, you may need a full-service agency. If your team is strong, you may want a specialized implementation partner or optimization partner.

7) Compare the team, not just the pitch

The people who sell the project may not be the people doing the work.

Ask who will actually be assigned:

• Project manager
• Technical architect
• Front-end developer
• Back-end developer
• CRO strategist
• UX designer
• QA lead
• SEO specialist
• Analytics specialist

Then ask about:

• Seniority
• Availability
• Location/time zone fit
• Whether they use contractors
• Who owns communication

A great pitch from a senior person can turn into a mediocre delivery team if you don’t check.

8) Look at their process and communication style

Migration projects need good project management.

Ask:

• How often will we meet?
• What do status updates look like?
• How are risks raised?
• How do you handle change requests?
• What happens if scope changes mid-project?

You want an agency that is transparent, organized, and proactive, not one that only communicates when you ask.

9) Compare pricing by value, not just rate

Cheaper is not always cheaper if the migration goes wrong.

Compare:

• Fixed fee vs time and materials
• What’s included vs excluded
• Post-launch support window
• Warranty / bug-fix period
• Ongoing optimization retainer structure
• Ownership of code, designs, and documentation

Ask them to break down:

• Migration cost
• QA/testing cost
• SEO support
• Analytics setup
• Post-launch stabilization
• Ongoing optimization services

A low bid with unclear scope often becomes expensive later.

10) Ask for references from similar clients

Don’t just ask for references; ask specific questions:

• Did they hit deadlines?
• Were there surprises?
• How did they handle issues?
• Were they strategic or just task-based?
• Did results continue after launch?
• Would you hire them again?

If possible, talk to a client who did both migration and ongoing optimization with them.

11) Watch for red flags

Be cautious if they:

• Promise guaranteed revenue growth
• Downplay migration risk
• Don’t ask many questions
• Have weak SEO migration planning
• Can’t explain their testing process
• Focus only on aesthetics
• Lack platform-specific experience
• Have poor documentation and handoff practices
• Are vague about who does the work
• Give you an unrealistically fast timeline

12) Use a scoring matrix

A simple scorecard can help compare agencies objectively. Score each 1–5 on:

• Platform migration experience
• Technical depth
• SEO migration expertise
• Analytics/CRO capability
• Relevant case studies
• Project management
• Team quality
• Communication
• Pricing/value
• Cultural fit

Weight the categories based on your priorities. For example:

• If the migration is risky, put more weight on technical and SEO expertise.
• If the platform is stable and you mainly need growth, weight optimization and experimentation more heavily.

13) Choose the right engagement model

Common models:

• Full-service agency

  • Best if you need migration plus ongoing optimization and have limited in-house resources

• Specialist migration agency + separate CRO partner

  • Best if you want best-in-class execution in each phase

• Implementation partner with optimization retainer

  • Best if you want continuity and one vendor relationship

There’s no universally best option. The key is whether one team can genuinely excel at both phases.

A simple decision rule

Choose the agency that can clearly show:

1. Proven migrations on your type of platform and complexity
2. A structured, low-risk launch process
3. Real optimization methodology, not just ideas
4. The exact team that will work on your account
5. A strong communication and measurement plan

If you want, I can also give you:

• a vendor scorecard template
• a list of questions to ask in agency interviews
• or a RFP checklist for migration + optimization