- Evidence over opinion
- Rigorous A/B testing
- Ethical, accessible CRO
CRO · Research, A/B testing and UX
CRO agency: turn the traffic you already have into customers
As a CRO agency, we improve what happens after the click: we research why visitors don't buy, book or get in touch, test fixes with A/B tests when traffic allows and roll out what works, with no tricks.
Personal reply, No obligation, English, Español
What it is
What CRO is and why it comes before more traffic
Conversion rate optimisation (CRO) is the systematic work of understanding why website visitors don't take the next step, then removing what holds them back. It relies on data, user research and controlled tests, not opinions or design fashions.
It's often better value than buying more traffic: every gain makes what you already spend on Google Ads, social media or SEO work harder, and it lasts when campaigns pause.
Whether you need a CRO consultant for one funnel or ongoing conversion rate optimisation services, we work on existing sites. New sites belong to web design, in-depth usability audits to UX/UI and accessibility, and everything starts with reliable tracking.
In depth
A website conversion audit starts with evidence
A website conversion audit pinpoints where and why visitors drop off before proposing any change. We combine quantitative data (where people leave) with qualitative research (why) and finish with hypotheses prioritised by impact, evidence and effort.
The numbers come from GA4 and your shop or CRM: funnels by device, language and source, and abandoned forms. The why comes from heatmaps and recordings (with consent and personal fields masked), surveys, user tests and an expert usability review. AI clusters answers and summarises recordings; decisions stay human.
- Leaks: the funnel step where each segment drops off.
- Message: whether the page answers what the visitor came for.
- Friction and trust: long forms, errors, slow pages and unanswered doubts.
In depth
A/B testing: when it makes sense and when it doesn't
An A/B test compares two versions of a page with real traffic to find which converts better, beyond chance. It's only reliable with enough conversions; otherwise, other methods give better, faster answers.
As an A/B testing agency, we fix the hypothesis, primary metric and smallest change worth detecting before launch, then size the sample. Tests run in full weeks, aren't stopped early, and losing variants are documented too.
With low traffic we switch method: user testing, bolder changes measured before and after, or tests on a higher-volume step. For seasonal businesses, we keep tests from straddling two seasons: August visitors don't decide like February ones.
In depth
Landing page optimisation and forms that convert
A landing page converts when it delivers what the ad or search promised, loads fast, makes sense in seconds and asks only for essentials. We work on it in every language, because a literal translation rarely answers a foreign searcher's questions.
We work to Google's Core Web Vitals thresholds: LCP of 2.5 seconds or less, INP under 200 milliseconds and CLS below 0.1. INP measures response to taps and typing, exactly what forms need; code changes are coordinated with technical SEO.
For forms: fewer fields, clear error messages, the GDPR first-layer notice by the button and express consent for marketing messages, as Spain's LSSI-CE generally requires. Customers who prefer to ask first may convert better through a WhatsApp AI chatbot.
In depth
Ethical conversion: no dark patterns
Ethical CRO lifts conversion by helping people decide, not by misleading them. The EU Digital Services Act, fully applicable since 17 February 2024, bans online platforms from using deceptive designs, or dark patterns, and we apply the same rule on every site.
That rules out fake urgency, resetting countdowns, pre-ticked boxes and hidden cancellations. Nor do we optimise the cookie banner against the rules: under the AEPD guide, 'reject' must sit in the same layer, at the same level and with a similar mechanism to 'accept'.
Social proof only counts when it's real: in July 2026 Google added a rule against fake and undisclosed incentivised reviews to its review snippet guidelines. Accessibility also removes friction: since 28 June 2025, Spain's Law 11/2023 has required accessible consumer e-commerce, with micro-enterprises exempt.
In depth
Growth experimentation beyond the website
Growth experimentation applies the CRO method to the whole journey: the offer, ad messaging, welcome emails, pricing pages or software sign-ups, logged so no test is repeated.
We rank ideas by impact, evidence and effort, at a pace your team can sustain, and share learnings with whoever runs the ads or plans the season. It pairs with digital strategy when deciding where to grow, and marketing automation when the next step happens off-site.
What's included
What our CRO programme includes
Eight components, combined to suit your goals.
Website conversion audit
Data, expert usability review and funnel leaks, in a prioritised report.
User research
Surveys, user tests, heatmaps and recordings captured with consent.
Hypothesis backlog
Ideas ranked by impact, evidence and effort, each with its metric.
Variant design
Copy, layouts and flows, designed and built by the same team.
A/B testing programme
Sample sizing, set-up, QA and analysis against criteria set in advance.
Landing pages and forms
Messaging matched to the ad, less friction and legal notices in place.
Accessibility and performance
Barriers and Core Web Vitals issues that hold back conversion.
Experiment log
Every test, result and learning, documented and owned by you.
How we work
How we run CRO, step by step
A loop paced by your traffic and development capacity.
Phase 01 / 06
Tracking check
Conversions must record correctly; without reliable data, tests mislead.
Phase 02 / 06
Research
Data, recordings, surveys and user tests.
Phase 03 / 06
Hypotheses and priorities
A list ranked by impact, evidence and effort, agreed with you.
Phase 04 / 06
Design and test
Reviewed variants, launched as an A/B test or a measured change.
Phase 05 / 06
Analyse and implement
We read results against agreed criteria and ship what wins.
Phase 06 / 06
Learn
We document what we learned and feed the next loop.
The SERMAN approach
Why optimise with SERMAN
Evidence over opinion
Every change starts from data or user observation.
Design, build and data together
One team researches, designs, codes and measures, with fewer hand-offs per loop.
Ethical and accessible by default
No dark patterns or invented social proof; accessibility counts as conversion.
What it is not
What this service isn't
- We don't promise uplift percentages: they depend on your starting point, traffic and offer.
- No fake urgency, invented countdowns, pre-ticked boxes or other dark patterns.
- No invented reviews or testimonials, and no undisclosed incentivised reviews.
- It isn't changing button colours at random: no hypothesis, no test.
- We don't run tests without enough traffic; if it's lacking, we use another method.
What we measure
The indicators that show CRO is working
Business outcomes, not button clicks.
Conversion by segment
By device, language, source and page type, never just the average.
Drop-off by step
Where people leave forms, bookings or checkout.
Value per visit
Revenue or lead value per session, plus average order value for shops.
Lead quality
Which enquiries become customers, according to your CRM.
Page experience
Real-user Core Web Vitals, INP included, on key pages.
Learning velocity
Tests completed and learnings documented each cycle.
Tools & platforms
Tools we work with
- Google Analytics 4
- Microsoft Clarity
- Hotjar
- VWO
- AB Tasty
- Optimizely
- Lyssna
- Figma
- PageSpeed Insights
- axe DevTools
Who it's for
A particularly good fit if…
- You invest in advertising but your site converts little of it.
- You run an online shop and need ecommerce conversion rate optimisation for basket and checkout.
- You generate leads in health, education or professional services and your form loses people.
- You sell software with a free trial and sign-ups stall.
- Your site serves several languages and one version underperforms.
- You're planning a redesign and want to decide with data.
Compliance
Rules we respect when optimising
This is not legal advice.
EU Digital Services Act
Bans deceptive designs on online platforms; we apply it on every site.
Cookies and recordings
Heatmaps and recordings using non-exempt cookies only after consent, per the AEPD guide.
Accessibility (Law 11/2023)
Accessible consumer e-commerce since 28 June 2025, with micro-enterprises exempt.
Forms (GDPR and LSSI-CE)
A first-layer privacy notice by every form and express consent for marketing messages.
FAQ
Frequently asked questions
What is CRO and how does it help you sell more?
CRO, or conversion rate optimisation, means researching why visitors don't buy, book or get in touch, then fixing it with tested changes. It improves the return on the traffic you already have, without paying for extra visits.
What is a good website conversion rate?
There's no universal figure: it depends on sector, price, traffic source, device and what you count as a conversion. The useful benchmark is your own rate, by segment, and how it moves.
How much traffic do I need for an A/B test?
It depends on your current conversion rate and the smallest change you want to detect: the smaller the difference, the more conversions you need. We size the sample first; if a test would take months, we use another method.
What does a CRO audit include?
Funnel analysis in GA4 and your shop or CRM, heatmaps and recordings with consent, a usability, accessibility and speed review, user research and a prioritised hypothesis list.
How do you improve a landing page's conversion rate?
Match the message to the ad or search behind the visit, make the offer clear on the first screen, cut form fields, load fast on mobile and answer doubts honestly. Then test rather than assume.
What are dark patterns and why avoid them?
Designs that push people into choices they wouldn't make with clear information: fake urgency, pre-ticked boxes or hidden cancellations. The EU Digital Services Act bans them on online platforms, and they destroy trust.
How is CRO different from a redesign?
A redesign changes a lot at once and rarely shows what worked. A CRO agency changes what the evidence points to, measures every improvement and keeps what works.
Related services
Pairs well with
Analytics, First-Party Data & Server-Side Tracking
GA4, first-party data, server-side tracking and Consent Mode v2 set up properly: reliable, lawful data you own, the base for campaigns and reports.
UX/UI Design & Web Accessibility
Research, interfaces and design systems people grasp first time, plus WCAG 2.2 AA accessibility audits and a plan to fix what fails.
Web Design
Premium bilingual websites with purposeful motion, accessible by default and fast by design, built for people, Google and AI agents.
Google Ads Management
Google Ads for the AI Max era: Search, Performance Max and Demand Gen on reliable tracking, in an account you own.
Digital Strategy & Fractional CMO
Digital marketing strategy and fractional CMO leadership: a diagnosis, a channel and budget plan, and a growth system you can measure.
Contact
Start with a CRO audit
We'll show you where visitors drop off, why, and what we'd test first.
Personal reply, No obligation, English, Español
Start with SERMAN
Tell us about your project
First conversation
Diagnosis and proposal