CRO services for agencies: outsourced A/B test development
Most CRO agencies can research and design tests faster than their developers can build them. I am the build layer you plug in when the queue backs up: I take your briefs, build the tests on your client's platform, QA them to your process, wire the tracking and remove them cleanly when they end. Your client sees your agency, not me. Billed per brief, no retainer. In-house teams with their own programme use the same service.
Arafat Islam is a freelance CRO developer and A/B test developer with 7+ years and 500+ shipped tests, working UK and US hours for retailers, DTC brands and CRO agencies. Company: Arafatcro Ltd, UK.
Build capacity, available now
Send a test brief, or book a call about a regular flow of builds. Hour estimate within one UK business day. No retainer, no minimum.
How white-label work runs
- Your brief, your process. I build from your test plans and designs, follow your QA checklist and naming conventions, and hand back in whatever format your team reviews.
- Invisible to your client. I work in your Slack, Jira or Trello and on your client's platform accounts. Nothing carries my name.
- Your hours. UK and US business hours, so builds are ready for your reviews and launches.
- One test or a steady flow. A single overflow build is as welcome as a weekly run of tests, and regular volume earns a discounted rate.
- Supplier paperwork that checks out. You contract a UK limited company with a Companies House number, and confidentiality terms are fine.
What each build includes
Every test is built to run correctly on your live site and to return data you can trust. That means:
- The variation build. JavaScript and CSS on your testing platform, written to survive single-page apps, late-rendering elements and React inputs.
- Anti-flicker that hides the element, not the page, so the control never flashes and Core Web Vitals stay inside budget.
- Tracking for every goal, wired through GA4, Tealium or your data layer, with a check that the split in your analytics matches the split in your testing tool.
- QA across browsers and devices, including keyboard access for anything interactive.
- A clean revert and a handover: the code, the QA notes and the tracking plan, so your team can read and reuse all of it.
What it does not include
Research, hypotheses, design and the statistical read-out of results. Those are the strategy half of conversion rate optimisation, and a CRO consultant or agency does them well. If you have a strategist, or an agency whose research moves faster than its developers can build, this service is the other half. If you have neither, the hiring guide covers when to start with a consultant.
Consultant, agency or developer?
| You need | Hire | What you pay for |
|---|---|---|
| Someone to find what to test | A CRO consultant | Research, hypotheses, a roadmap |
| Research, design, build and analysis in one place | A CRO agency | A retainer covering all of it |
| Tests built from ideas you already have | A CRO developer | The build, QA, tracking and revert, per brief |
Builds with published results
- Self-configuring cost comparison on HomeServe PDPs: +13.6% conversion, +53.5% revenue (Webtrends Optimize)
- Cross-sell banner on a HomeServe PDP: +12.3% conversion (Webtrends Optimize)
- Add-to-bag interstitial CTA on Screwfix: +10% conversion (Optimizely)
- Trustpilot reviews on a Red Cross First Aid course page: +9.08% conversion (VWO)
Platforms
The same build, on whichever platform you already use:
How pricing works
Submit a brief and you get an hour estimate back within one UK business day, with a total you approve before any work starts. A single test usually takes between 2 and 20 build hours: a copy or layout change sits near the bottom of that range, a new component or a multi step flow near the top. Regular volume earns a discounted rate, and there is no lock-in: one-off builds are as welcome as a weekly commitment.
Add build capacity without adding headcount
For single test builds, a steady flow of tests for your own programme, or white-label build capacity for your agency. I reply within one UK business day.
Common questions
Do you work white-label for CRO agencies?
Yes. I build to your briefs and your QA process, in UK and US hours, inside your tools, and I stay invisible to your client. Your agency contracts Arafatcro Ltd, a UK limited company, on standard supplier terms.
What do conversion rate optimization services include?
It depends who is selling them. An agency usually bundles research, hypotheses, design, build and analysis. My service is the build: the variation code on your testing platform, QA across browsers and devices, the tracking for each goal, a check that the traffic split in your analytics matches the platform, and a clean revert when the test ends.
Do I need a CRO agency or a CRO developer?
If you already know what you want to test and have a platform, a developer is the faster and cheaper route. If you need someone to research your site and decide what to test, start with a CRO consultant or agency. Many agencies use freelance developers for the build anyway.
How much do conversion rate optimisation services cost?
Agencies usually sell a monthly retainer. I quote per brief: you get an hour estimate within one UK business day and approve the total before any work starts. Regular volume earns a discounted rate, and there is no retainer or minimum.
Which testing platforms do you work with?
Optimizely, VWO, Convert.com, Adobe Target, Dynamic Yield, Monetate, Intelligems, Webtrends Optimize, AB Tasty and Kameleoon.
Agencies contract and invoice Arafatcro Ltd, a UK limited company registered in England & Wales, on standard supplier terms. Company no. 17325504, verifiable on Companies House.