How to Compare Your Old and New Website Before Launch
Most migrations fail for one simple reason:
No one actually compares the old site to the new site at scale.
The homepage looks good.
A few products load.
Checkout works.
And then DNS gets flipped.
If you are redesigning, replatforming, or migrating to Shopify, you need a structured way to compare old vs new before launch.
Here is what that actually means.
Step 1: Build a Complete List of Old URLs
You cannot compare what you do not inventory.
Before migrating texasbeardcompany.com from AmeriCommerce to Shopify, we documented exactly 339 live URLs.
That included:
/natural-beard-oils/clove-citrus-beard-oil/beard-oil/store/p/33-Beard-Trimming-Scissors.html/blog/That-Uncomfortable-Itchy-Beard-Feeling
This list became the source of truth.
If you need a full framework, start with the
Shopify migration SEO checklist.
Your goal is simple:
Every URL that previously returned 200 should be tested against the new site.
Step 2: Compare Status Codes (Old vs New)
For each legacy URL, you need to answer:
- Did it return 200 before?
- What does it return now?
- Does it redirect?
- Where does it land?
In a clean migration, most legacy URLs should resolve as:
301 → 200
Anything else deserves investigation:
- 404 (missing page)
- 302 (temporary redirect mistake)
- 301 → 301 (redirect chain)
- 200 but wrong content
When we validated the AmeriCommerce to Shopify migration, we verified all 339 URLs and confirmed there were no redirect chains before flipping DNS.
That step alone prevented post-launch surprises.
For deeper redirect validation, see
How to verify redirects after a Shopify migration.
Step 3: Compare Performance, Not Just Functionality
A page can load and still be worse.
Comparing old vs new means measuring:
- TTFB
- Total load time
- Page weight
- Core Web Vitals
During the texasbeardcompany.com migration:
Mean TTFB improved from 327ms → 139ms.
However, average page size increased because the new Shopify theme included more JavaScript and CSS.
Both things were true.
Without side-by-side measurement, you would not know that.
Performance regressions are common in:
- Shopify theme rebuilds
- WooCommerce to Shopify migrations
- BigCommerce category remapping
- App-heavy redesigns
If you are not measuring both domains under the same conditions, you are guessing.
For a deeper dive into performance comparisons, read
How to measure TTFB before and after migration.
Step 4: Check for Missing Pages at Scale
Spot-checking ten URLs is not validation.
You need to know:
- How many legacy URLs now return 404?
- Which ones were intentionally removed?
- Which ones were accidentally missed?
For example, during our migration we intentionally allowed:
/texas-beard-co-affiliate-program/beard-care-subscription.html
to 404 because they were obsolete.
That is a business decision.
But if high-value pages disappear silently, you have a problem.
Comparing old vs new at scale surfaces those gaps immediately.
Step 5: Verify Final Destination Accuracy
A redirect can be technically correct and still be wrong.
For example:
If /beard-oil redirects to the homepage instead of the appropriate collection page, that is not a clean migration.
The correct comparison workflow confirms:
- Final URL
- Final status
- Logical content match
This is where many migrations leak authority slowly over time.
Step 6: Compare Screenshots (Optional but Powerful)
Functionally correct does not mean visually correct.
Template changes can introduce:
- Missing sections
- Broken layouts
- Hidden content
- CLS issues
Modern migration validation should include screenshot capture so you can visually confirm the new site renders as expected.
Especially for:
- Product detail pages
- Collection layouts
- Blog templates
When to Compare: Before and After DNS
The safest workflow looks like this:
- Compare staging or preview domain to old production.
- Fix redirect and performance issues.
- Flip DNS.
- Re-run comparison against live production.
When we flipped DNS in April 2025, we did it confidently because everything had already been validated against the 339-URL inventory.
No emergency patches.
No ranking collapse.
No scrambling.
The Difference Between “Looks Fine” and “Actually Verified”
Most teams manually click around and assume everything is good.
Real comparison means:
- Structured URL inventory
- Automated status validation
- Redirect path analysis
- Performance delta measurement
- Screenshot capture
- Repeatable reports
That is exactly what Cutover was built to do.
It compares your old domain and your new domain side-by-side, surfaces missing pages, flags redirect chains, measures performance changes, and generates a report you can trust before launch.
If you are replatforming to Shopify, switching themes, or consolidating domains, do not rely on gut feeling.
Compare the sites properly. Validate your migration with Cutover to surface problems before launch.
Then flip DNS.