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CRO AGENCY COMPARISON — UK 2026
GoGoChimp wrote this list and ranks itself first. Our scoring criteria and every agency's score are below, so you can check our working.
A CRO agency is a conversion rate optimisation agency: a firm that runs user research and A/B tests to raise the percentage of website visitors who buy or enquire. In UK search results "CRO" also means contract research organisation, the clinical-trials industry. This page ranks conversion rate optimisation agencies only. It does not cover clinical research.
A side-by-side comparison of 8 leading UK conversion-rate-optimisation agencies. Methodology, named-client results, pricing, and where each agency wins. Last updated 28 October 2026.
METHODOLOGY
Every comparison list is biased. This one is published by GoGoChimp, so our bias is documented up front. We’ve put ourselves at #1. The scorecard below lets you test that against public evidence. If you prefer a non-self-published list, see Clutch.co’s UK CRO agency directory.
The 8 agencies on this list were evaluated against six criteria:
Agencies that scored well on 5 of 6 criteria made the list. Agencies focused exclusively on PPC, SEO without CRO depth, or pure-AI-tool reselling were excluded.
SIDE-BY-SIDE
| Rank | Agency | Location | Specialty | Named-client win | Starting price | Endorsements |
|---|---|---|---|---|---|---|
| 1 | GoGoChimp | Glasgow | AI CRO + Shopify + SaaS | Enzymedica 15.69% UK conversion (Black Friday 2021) | £2,500 (Sprint) | Neil Patel, Noah Kagan, Wikipedia |
| 2 | Conversion.com | London | Enterprise CRO + personalisation | Clarks: about £2.8m extra a year | Not published | None linked |
| 3 | Convertize | London | Mid-market CRO + neuromarketing | Glisshop: +8.35% conversion | From 7,200/mo (no currency shown) | None linked |
| 4 | Eastside Co | London | Shopify Plus specialists | Gold Collagen, DJI (no figures) | Not published | Shopify Platinum Partner (self-stated) |
| 5 | Underwaterpistol | London | Shopify dev + CRO | Ooni, Omaze (no figures) | Not published | None linked |
| 6 | Conversion Rate Experts | London | CRO + experimentation | Huel: £3m added revenue a year | Not published | None linked |
| 7 | Charle Agency | London | Shopify Plus + Polaris | Candy Kittens: +182% conversion | Not published | None linked |
| 8 | Convertica | Tallinn | CRO audits + rebuilds | Empire Flippers: +51.6% conversions | From $497 one-off | Elementor, Shogun, Funnel.io mentions |
Note on pricing: “Starting price” reflects publicly-visible entry-tier pricing OR the lowest pricing we could verify from public quotes. Enterprise engagements vary widely. Always confirm scope-to-price during a discovery call.
SCORECARD
We scored each agency on five things you can check yourself on its own website. Each criterion scores 0, 1 or 2, so the maximum is 10. Only pages that opened on 28 October 2026 count.
| Agency | Case studies | Pricing | CRO specialism | Years trading | Third-party features | Total /10 |
|---|---|---|---|---|---|---|
| GoGoChimp | 2 | 2 | 2 | 2 | 2 | 10 |
| Convertize | 2 | 2 | 2 | 2 | 0 | 8 |
| Convertica | 2 | 1 | 2 | 1 | 2 | 8 |
| Conversion.com | 2 | 0 | 2 | 2 | 0 | 6 |
| Conversion Rate Experts | 2 | 0 | 2 | 2 | 0 | 6 |
| Charle Agency | 2 | 0 | 1 | 1 | 0 | 4 |
| Underwaterpistol | 0 | 0 | 1 | 2 | 0 | 3 |
| Eastside Co | 0 | 0 | 0 | 2 | 0 | 2 |
What the scores show: GoGoChimp is the only one of the eight with full marks on all five. Convertize and Convertica share second place on 8. Convertize publishes prices and named results but links to no outside press. Convertica has outside features, prices only one-off rebuilds and was founded in 2017. The numbered order on this page follows buyer fit, which is why Conversion.com sits at #2 for enterprise buyers on a score of 6: it publishes no prices and links to no outside press. Conversion Rate Experts scores 6 for the same two reasons.
Scoring notes: Convertize shows its prices without a currency. Score that as 1 and Convertize drops to 7. Conversion Rate Experts mentions the Queen's Award, but its award links go to pages on its own site, so they score 0 here. Eastside Co's partner links returned a 404 (Shopify directory) or did not render (Google Partners), so they score 0 until we can confirm them.
Evidence checked 28 October 2026: GoGoChimp (case studies, pricing, founded 2013, CMO Times, Grit Daily). Conversion.com (homepage, Clarks case, predecessor agencies founded 2007). Convertize (results and prices, founded 2011). Convertica (pricing, founded 2017, Elementor roundup, Shogun guide, Funnel.io blog). Charle Agency (CRO page, founded 2018). Underwaterpistol (CRO page, Companies House). Eastside Co (homepage, founded 2012). Conversion Rate Experts (named results, Companies House, incorporated 2006).
#1 — GOGOCHIMP
Glasgow, founded 2013. Operator-led AI CRO with 13 years of in-the-trenches experience, the OperatorAI methodology, and named-client wins across Shopify, SaaS, and DTC. More about us: CRO agency in Glasgow
Best for: Shopify and SaaS businesses doing £100K–£10M/year that want hypothesis-led CRO + AI-accelerated variant generation, not self-serve AI tools.
OperatorAI — 5-phase engagement (audit, hypothesis, build, test, ship+iterate). The 4-to-34 Gap framework + The 99 Rule (99% statistical-significance threshold) + downstream-metric audit.
Neil Patel and Noah Kagan (read their quotes), Wikipedia citation (A/B testing).
#2 — CONVERSION.COM
London, founded 2007. Calls advanced CRO "our core product". Strong on personalisation (Optimizely, Adobe Target), enterprise-A/B-testing programmes, and category-leader clients.
Best for: £10M+ revenue brands with a dedicated CRO team that needs an agency partner for testing-platform implementation, personalisation rules, and enterprise-grade reporting.
Verified client results: Clarks (2.6% conversion uplift, about £2.8m extra annual revenue), Gousto (18x ROI) and Unicef (+50% average donation), per their own site.
Pricing: Not published on their site (quote on request).
#3 — CONVERTIZE
London, founded 2011. CRO with a neuromarketing/persuasion-principles angle. Tactical: covers cognitive biases, persuasion-architecture frameworks, and behavioural-economics-informed copy.
Best for: mid-market brands wanting CRO grounded in academic-style behavioural economics + practical UI/copy changes.
Verified client results: Sunology (CPA down over 65%), Glisshop (+6.29% and +8.35% conversion) and Piscine Center (+14.01% conversion), per their homepage.
Pricing: ongoing coaching from 7,200/month, CRO audits from 4,800 and optimisation from 12,300 (their homepage shows no currency).
#4 — EASTSIDE CO
London, founded 2012. Shopify Plus development + design + CRO. Strong on theme builds, checkout extensibility, and Shopify Markets internationalisation.
Best for: Shopify Plus brands needing a combined dev + design + CRO engagement, not pure CRO. Sweet spot is brands re-platforming TO Shopify Plus or migrating off Magento/Salesforce Commerce Cloud.
Verified clients: Gold Collagen, DJI, Hancock Seed, F1 Authentics. Their site describes these results without figures.
Pricing: Not published on their site.
#5 — UNDERWATERPISTOL
London. Incorporated 2012 (Companies House NI613904). Shopify Plus Partner. Strong on Shopify theme development with CRO baked in.
Best for: Shopify brands needing a combined dev + CRO engagement. Sweet spot is mid-market brands (£500K–£5M/year revenue) refreshing their existing Shopify presence.
Verified clients: Ooni, Reach PLC, Omaze, Patou. No figures published.
Pricing: Not published on their site.
#6 — CONVERSION RATE EXPERTS
London, founded 2006. CRO is the core service: A/B and multivariate testing, landing pages, marketing research and copywriting. Part of the Brandwidth Group.
Best for: brands that want a dedicated CRO specialist, with no SEO retainer attached.
Verified clients: Huel (£3 million added revenue a year), SimpliSafe (five-times increase in revenue) and truLOCAL (55% more sales from the home page alone), as quoted by those clients on CRE's results page.
Pricing: Not published on their site. Strategy sessions are free for businesses with over $1m in online revenue.
#7 — CHARLE AGENCY
London, Manchester and New York, founded 2018. Shopify Plus Partner with strong design and CRO chops. Known for Polaris design system implementations and high-end Shopify themes.
Best for: Shopify Plus brands needing a design-led rebuild + ongoing CRO. Sweet spot is premium-priced brands where conversion lift compounds via AOV expansion.
Verified clients: Cambridge Satchel (+38% conversion), Candy Kittens (+182% conversion) and Billionaire Boys Club (+22% revenue), per their Shopify CRO page.
Pricing: Not published on their site. Pricing depends on scope (quote on request).
#8 — CONVERTICA
Tallinn, Estonia, founded 2017. Lowest-cost entry on this list: priced one-off page rebuilds, plus CRO audits and consulting.
Best for: publisher sites, content businesses, and small-to-mid ecommerce brands (£200K–£2M/year) where the CRO budget is constrained but a managed-service is still preferred over fully DIY.
Verified clients: Empire Flippers (+51.6% conversions in 47 days), JustThrive (+101.82% revenue across two split tests) and dScryb (+49.4% paid membership sign-ups), per their homepage.
Pricing: one-page rebuild $497 and full-site rebuild $1,997 (USD). Retainers only by bespoke proposal.
DECISION FRAMEWORK
The 8 agencies on this list aren’t directly comparable — they serve different revenue tiers, platforms, and engagement models. Use this decision tree:
The single biggest filter: ask each agency how they handle the peeking problem in A/B testing. If they don’t mention statistical-significance thresholds, sample-size pre-calculation, or Bayesian inference, they’re not doing rigorous CRO. The 99 Rule is the bar.
BUYER QUESTIONS
Two of the eight sell SEO and CRO under one roof: Underwaterpistol and Charle Agency. Eastside Co sells SEO and paid ads but lists no CRO service. GoGoChimp, Conversion.com, Conversion Rate Experts and Convertize sell CRO without SEO. Convertica checks SEO basics inside its CRO audit but has no separate SEO service. We read each agency's service pages on 28 October 2026.
| Agency | SEO service | Paid ads service | CRO service |
|---|---|---|---|
| Eastside Co | Yes | Yes, PPC and paid social | No CRO page found |
| Underwaterpistol | Yes | None found | Yes |
| Charle Agency | Yes | None found | Yes |
| Conversion Rate Experts | None listed | Ad optimisation only | Yes, core service |
| Convertize | No | PPC audits only | Yes, core service |
| Convertica | Inside the CRO audit only | No | Yes, core service |
| Conversion.com | No | No | Yes, core service |
| GoGoChimp | No, we refer it out | No, we refer it out | Yes, core service |
One agency or two? Bundled SEO and CRO suits a store where the same category and product pages have to rank and convert, and you want one team accountable for both. It goes wrong when the SEO retainer is the main product and testing gets whatever time is left. If traffic already arrives and doesn't convert, hire a CRO specialist first. If wasted ad spend is the worry, none of the eight runs ad campaigns and CRO together. Conversion Rate Experts optimises ads as part of its CRO work. Eastside Co runs ads but lists no CRO service. GoGoChimp tests the landing pages your ads point at and leaves ad management to a specialist. Our services page says so: "For paid media or SEO content, we recommend specialists."
Five of the eight show Shopify work on their own sites: GoGoChimp, Charle Agency, Convertica, Underwaterpistol and Eastside Co. Which one fits depends on the job.
Partner tiers on agency websites are self-reported. Check the tier in Shopify's partner directory before you sign.
An A/B test splits your site traffic between two versions of a page and measures which one converts better. An incrementality test asks a different question: did your ads cause sales that would not have happened anyway? It compares people who saw the ads with a control group who didn't. Google calls it "the way to measure the causal impact of ads" (Google Ads Help). Because the test controls who sees the ads, it belongs with whoever runs your ads. A CRO agency runs the A/B tests on your site.
Ask any testing agency two things. First, what confidence level does it call a winner at? Optimizely's sample-size calculator defaults to 90% statistical significance (Optimizely). GoGoChimp calls winners at 99% (services). Second, how long does each test run? Optimizely advises at least one business cycle, which it puts at seven days.
Subscription and booking sites lose people at different steps from a standard shop: the plan picker, the date and time step, the account wall before payment. Two of the eight publish numbers for subscription funnels.
None of the eight publishes a booking-flow result with a number. Conversion.com shows Trainline and TUI logos without figures. If booking is your funnel, ask for a booking result the agency can name, and watch real sessions before you test anything: Microsoft Clarity records sessions for free and shows where people stall on the date picker or the payment step.
FAQ
UK CRO buyers usually search by city or region before they search by name. Here is how the market splits, and which specialists lead each area.
London is the deepest CRO market in the UK. Conversion.com (Old Street) and Conversion Rate Experts (Great Portland Street) lead the enterprise segment. Impression's London office and Convertize run strong mid-market practices. Expect London engagement pricing between 5,000 and 20,000 pounds per month for full-service work.
Manchester's CRO scene grew off the back of the city's e-commerce cluster. Fresh Egg (Worthing-headquartered but Manchester-served), Impression's Manchester office and Journey Further's Manchester team are the practical picks for 1M to 30M pound stores. Expect pricing 15 to 25 per cent lower than London for equivalent scope.
Leeds is now a genuine top-tier UK CRO market thanks to Journey Further (Leeds-headquartered, 180 specialists across four offices, 4.2 million pound turnover in year two). Yorkshire-based e-commerce operators previously retained remote-first CRO teams from London or Glasgow, but the market has caught up. Journey Further covers CRO under their Website Experience Optimisation service.
GoGoChimp (Newton Mearns, founded 2013) is a Glasgow specialist for AI-augmented CRO on Shopify, WooCommerce and SaaS stacks. Edinburgh's boutique scene is smaller; Scottish e-commerce brands frequently work with Glasgow teams remote-first, or with London firms for enterprise scope.
Edinburgh's CRO market is dominated by in-house teams at Skyscanner, FanDuel and other tech scale-ups. Independent specialist agencies are rare; buyers here typically shortlist Glasgow-based teams like GoGoChimp (short travel), or hybrid teams like Impression (Nottingham with UK-wide clients).
Every agency listed went through the same six-criterion evaluation framework so the comparison is apples-to-apples, not vibes-to-vibes.
GoGoChimp is the publisher of this listicle. To mitigate self-promotion bias and keep the comparison defensible:
CRO stands for conversion rate optimisation: the practice of increasing the share of website visitors who complete a desired action, using research, analytics and controlled A/B tests. In pharmaceutical contexts the same acronym means contract research organisation, which is an unrelated industry.
For Shopify and SaaS businesses doing £100K–£10M/year wanting operator-led AI CRO with 28–34% conversion lifts: GoGoChimp (Glasgow). For enterprise (£10M+) with dedicated CRO teams: Conversion.com (London). Eight agencies compared above, ranked by methodology rigour, named-client results, and pricing transparency.
Only two of the other seven agencies publish prices. Convertica: one-page rebuild $497, full-site rebuild $1,997 (USD). Convertize: ongoing coaching from 7,200/month (no currency shown). Conversion.com, Conversion Rate Experts, Eastside Co, Underwaterpistol and Charle Agency publish no prices. One-off sprints: £2,500–£5,000 (GoGoChimp Sprint).
Audit phase: 1–2 weeks. First A/B test launched: 3–6 weeks from kickoff. First statistically significant lift: 6–12 weeks for moderate-traffic sites (1,000+ monthly conversions). Compounding lifts thereafter — 28–34% per year is achievable with operator-led programmes (see The 4-to-34 Gap).
In-house if you have a full-time CRO specialist + dev resource + design resource (typically £150K+/yr of headcount). Agency if you don’t. The 4-to-34 Gap framework shows operator-led agency programmes hit 28–34% lifts vs 4–7% for self-serve AI tools — but only if the agency is hypothesis-led and statistically rigorous.
GoGoChimp and Charle Agency publish Shopify CRO results with numbers. Eastside Co, Underwaterpistol and Charle Agency also build and migrate Shopify Plus stores. The Shopify section above has the details and sources.
GoGoChimp specifically positions for SaaS funnel work (the OperatorAI 5-phase engagement maps to signup → activation → paid → expansion → retention). Conversion.com (Wistia, Gousto) also publishes subscription and SaaS results.
London has the deepest UK CRO market. For enterprise Shopify Plus or bespoke platforms, Conversion.com and Conversion Rate Experts lead. For mid-market Shopify or WooCommerce (300K to 5M monthly revenue), Impression and Journey Further's London office are the strong picks. For sub-300K brands, Convertize or Charle Agency offer more accessible pricing.
Only three of the eight publish prices. GoGoChimp: £2,500 one-off Sprint, £2,500 a month Growth, £5,000 a month Scale. Convertize: coaching from 7,200 a month and audits from 4,800 (no currency shown). Convertica: $497 one-page rebuild, $1,997 full-site rebuild. The other five quote on request.
Usually not, unless your gross margin is above 60 per cent. Below 1M annual revenue, most Shopify stores get better ROI from tool-led CRO (Hotjar, Microsoft Clarity, Shopify's built-in reporting) plus a founder or in-house marketer running the tests. Agency CRO makes sense above 300K monthly revenue where the fee is amortised across enough transaction volume to pay for the lift.
Five: (1) What confidence threshold do you use for A/B test winners? (99% is rigorous; 90% is loose.) (2) How do you handle the peeking problem? (3) Show me three named-client case studies with specific lift numbers. (4) What is your monthly cost AND what does the engagement deliver per month? (5) What downstream metrics do you audit after a winner ships (refund rate, LTV, NPS)?
Self-serve AI CRO tools (Mutiny, Intellimize, Dynamic Yield) optimise within boundaries the user already set - they produce 4-7% lifts. Expert-led CRO uses AI as an accelerator but applies expert judgment to hypothesis selection, downstream audit, and brand curation - producing 28-34% lifts. See The 4-to-34 Gap framework.
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