Is a CRM agency the same as a retention agency in the UK?

Agencies in the UK usually sell this work as CRM. Here CRM means email and SMS lifecycle programmes, segmentation and repeat-purchase revenue, not the Salesforce or HubSpot sales-CRM implementation the same word means in the US and DACH. Affinsy's October 2026 ranking of the 20 best CRO, CRM and retention agencies in the UK scores all of them on the same five pillars, whatever each calls itself, led by Underground Ecom at 80/100.

How does Affinsy score retention and CRO agencies?

Each agency is scored 0-100 across five pillars: proven results (30 points), specialization (20), data sophistication (20), reputation (15) and track record (15). Scoring uses publicly verifiable evidence collected in October 2026, weighted by tier: independently verified evidence beats self-published, and self-published beats claimed. Underground Ecom scored 80, Get Better scored 69 and ConversionWise scored 66 in the UK.

Can an agency pay to be listed or to rank higher?

No. Rank position is never purchasable and no agency pays to appear in the ranking. Verification is free, and factual corrections to a listing never change the score.

What does the Verified Data-Driven badge mean?

It means the agency stood behind its listing with Affinsy directly and its data-capability claims held up to a hands-on review: a case study or work example, or one Affinsy analysis run on a client store. Underground Ecom carries the badge in the UK.

How often is the ranking updated?

Monthly. The current edition is October 2026, last updated October 6, 2026, and the next edition publishes November 4, 2026. Rankings are recomputed from evidence each edition, so positions move between editions.

How is this different from Clutch, G2 or other agency directories?

Review directories order agencies by the volume and rating of client reviews they collect. This ranking scores what an agency has publicly demonstrated: published results, specialization, data capability (segmentation, LTV modelling, basket analysis, structured testing), reputation and track record, each weighted by how independently the evidence can be verified. Review counts feed only the reputation pillar (15 of 100 points), so an agency cannot climb this list on reviews alone.

Which of these agencies specialize in Shopify stores?

ConversionWise (#3), Swanky (#4), Blend Commerce (#9), That Works Agency (#11), Shawfire Media (#13), Proof3 (#14), Eastside Co (#16) and PM Digital (#17) name Shopify or Shopify Plus in their published focus or case studies in the UK. Most agencies in the list work across Shopify, WooCommerce and Magento; this answer lists only the ones whose public material calls out Shopify specifically.

Which are the best Klaviyo agencies in the UK?

12 of the 20 agencies in the UK reference Klaviyo in their published focus, partner status or case studies: Underground Ecom (#1), Get Better (#2), Swanky (#4), PAASE (#6), Enchant Agency (#7), Email Kong (#8), Blend Commerce (#9), Melusine Studio (#10), Shawfire Media (#13), ElliotDigital (#15), Eastside Co (#16) and Sendfluence (#20). The highest-scoring of them is Underground Ecom at 80/100.

Which cities are these agencies based in, and do they work with brands elsewhere in the UK?

Headquarters represented in the October 2026 edition: London; North Devon; Bristol; Exeter; Milton Keynes area; Stratford-upon-Avon; Leeds; Sheffield & London; Manchester; Shrewsbury; Birmingham; Northern Ireland (remote). Every agency in the list works remotely with e-commerce brands across the United Kingdom, so a brand in a city not listed here is not limited to local firms.

Affinsy Rankings · October 2026 edition

Best Retention, CRM & CRO Agencies in the UK, 2026

The 20 strongest retention, lifecycle and CRO agencies we found for e-commerce brands in the UK, scored 0-100 on proven results, specialization, data sophistication, reputation and track record. This is Affinsy's opinionated take, weighted toward demonstrated data work; rank position is never purchasable.

Researched: Affinsy team, October 2026
Updated: October 6, 2026
Next edition: November 4, 2026
Evidence cutoff: October 30, 2026

01 · At a glance

The 20 best retention and CRO agencies in the UK

Underground Ecom ranks #1 in Affinsy's October 2026 ranking of retention and CRO agencies in the UK, scoring 80 of 100, ahead of Get Better (#2, 69/100) and ConversionWise (#3, 66/100). All 20 agencies in the UK are scored on the same five pillars: proven results, specialization, data sophistication, reputation and track record.

Affinsy ranking of retention and CRO agencies in the UK, October 2026 edition: rank, agency, focus, total score out of 100 and the five pillar scores behind it (results /30, specialization /20, data sophistication /20, reputation /15, track record /15). Sortable by any score column.
	Agency	Focus							Full listing
#1	Underground Ecom	Email / SMS	80/100	27	20	14	11	8	Full listing ↓
#2	Get Better	Email / SMS	69/100	26	20	10	6	7	Full listing ↓
#3	ConversionWise	CRO	66/100	28	10	4	10	14	Full listing ↓
#4	Swanky	CRO	65/100	25	15	6	8	11	Full listing ↓
#5	AWA Digital	CRO	64/100	27	17	6	5	9	Full listing ↓
#6	PAASE	Email / SMS	63/100	27	20	8	3	5	Full listing ↓
#7	Enchant Agency	Email / SMS	61/100	19	17	10	8	7	Full listing ↓
#8	Email Kong	Email / SMS	60/100	25	17	6	6	6	Full listing ↓
#9	Blend Commerce	CRO	59/100	26	10	10	7	6	Full listing ↓
#10	Melusine Studio	Email / SMS	56/100	26	17	8	0	5	Full listing ↓
#11	That Works Agency	CRO	54/100	25	14	4	4	7	Full listing ↓
#12	Converted	CRO	51/100	26	10	6	0	9	Full listing ↓
#13	Shawfire Media	Email / SMS	51/100	22	14	6	3	6	Full listing ↓
#14	Proof3	CRO	50/100	25	10	6	2	7	Full listing ↓
#15	ElliotDigital	Email / SMS	49/100	21	17	4	3	4	Full listing ↓
#16	Eastside Co	Email / SMS	44/100	20	6	4	3	11	Full listing ↓
#17	PM Digital	CRO	41/100	20	6	10	2	3	Full listing ↓
#18	Browser to Buyer	CRO	41/100	18	14	6	1	2	Full listing ↓
#19	Customers Who Click	CRO	36/100	18	4	6	5	3	Full listing ↓
#20	Sendfluence	Email / SMS	34/100	20	6	4	2	2	Full listing ↓

Click a score column to sort by that pillar; ties keep rank order.

02 · The ranking, scored

Email / SMS lifecycleCRO / experimentationFull retention

#1 Underground Ecom

Email / SMS

London, UK · Email/SMS lifecycle & retention · undergroundecom.com · Founded 2018

80/100

Rank #1 of 20 in the UK

Underground Ecom: London-headquartered retention agency (120+ staff, part of supergroup) and a Klaviyo Elite Master partner that describes itself as Klaviyo's largest Elite partner. Underground Ecom was one of Klaviyo's EMEA Agency Partners of the Year 2025.

Why Underground Ecom ranks #1 in the UK: Leads the UK list on nearly every pillar: quantified cases (SeoulBox +287% revenue), top Klaviyo tier, evidenced RFM/LTV/testing capability, benchmarks data product and real review volume. The reference point for the category in Europe.

Score composition80 of 100 pts

−20

Results

27/30

SeoulBox +287% revenueKlaviyo Elite Masterone of Klaviyo's EMEA Agency Partners of the Year 2025source ↗

Specialization

20/20

Klaviyo Master Elite

Data sophistication

14/20✓ Verified Data-Driven

Evidence found:segmentation / RFM+4structured testing+4attribution+2predictive LTV+4No public evidence:cross-sell / basket analysisCDP

Reputation

11/15

4.2/5 across 40 on Trustpilotawards and community footprintsource ↗

Track record

8/15

since 2018 (8 years)team 120+

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#2 Get Better

Email / SMS

North Devon, UK · Klaviyo CRM and retention for DTC · getbetter.co.uk

69/100

Rank #2 of 20 in the UK

Get Better: North Devon CRM and retention agency working almost entirely inside the Klaviyo ecosystem, one of two Klaviyo Elite Master partners in the UK. Grew from founder Rich Evans to a team of roughly 18 to 25 in three years, serving brands from $1M to $500M across the UK, US and EU.

Why Get Better ranks #2 in the UK: Top Klaviyo tier plus the deepest documented flow work in the list outside London, with PerfectTed showing flow revenue up 245% and campaign revenue up 607% month over month. The one hole is third-party proof: no Clutch, Trustpilot or Google review presence at all, so every claim traces back to its own site.

Score composition69 of 100 pts

−31

Results

26/30

PerfectTed: flow revenue +245.63%, campaign revenue +607.61% month over month, Buy Again journeys +405.51%source ↗

Specialization

20/20

Klaviyo Elite Master

Data sophistication

10/20Not yet verified

Evidence found:segmentation / RFM+4structured testing+4CDP+2No public evidence:predictive LTVcross-sell / basket analysisattribution

Reputation

6/15

no reviews found publiclyawards and community footprint

Track record

7/15

team ~18-25

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#3 ConversionWise

CRO

Bristol, UK · CRO / conversion design for Shopify DTC · conversionwise.com · Founded 2013

66/100

Rank #3 of 20 in the UK

ConversionWise: Bristol conversion-design agency (70+ team) focused on post-click optimization for Shopify DTC: landing pages, offer testing and conversion-focused design for 4,000+ brands since 2013.

Why ConversionWise ranks #3 in the UK: Unmatched scale and social proof in UK CRO (352 Trustpilot reviews at 4.8; GBP 1B+ tracked client revenue). Design-led methodology shows less deep experimentation/data evidence than research-driven CRO firms, which caps the data pillar.

Score composition66 of 100 pts

−34

Results

28/30

4,000+ DTC brandsGBP 1B+ tracked client revenue7,500+ conversion pages since 2013source ↗

Specialization

10/20

Conversion Rate Academyteam of 70+

Data sophistication

4/20Not yet verified

Evidence found:structured testing+4No public evidence:segmentation / RFMpredictive LTVcross-sell / basket analysisattributionCDP

Reputation

10/15

4.8/5 across 352 on Trustpilotawards and community footprintsource ↗

Track record

14/15

since 2013 (13 years)team 70+

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#4 Swanky

CRO

Exeter, UK · Shopify Plus CRO & experimentation programs · swankyagency.com · Founded 2010

65/100

Rank #4 of 20 in the UK

Swanky: Exeter-headquartered Shopify Plus agency founded in 2010, with teams in the UK, Australia and France. Alongside builds and migrations it runs one of Europe's most established ecommerce experimentation practices: a structured test-and-learn CRO program on Optimizely, VWO, Kameleoon and Convert.

Why Swanky ranks #4 in the UK: Elite Shopify credentials and a deep, quantified case library, but the CRO numbers stay at the outcome level: no published experiment teardowns, and its retention leg has no lifecycle-platform credential such as a Klaviyo tier. Publishing test-level detail and a segmentation or LTV artifact would push the data pillar past the specialist email shops.

Score composition65 of 100 pts

−35

Results

25/30

651% gross-sales uplift nine days after replatform213% ROI from 17 winning tests in year one66% of tests deliver a commercial uplift5.0 from 35 reviews on Shopify's directorysource ↗

Specialization

15/20

Shopify Platinum Partner (directory-verifiedpartner since 2011, one of ~25 globally)

Data sophistication

6/20Not yet verified

Evidence found:structured testing+4attribution+2No public evidence:segmentation / RFMpredictive LTVcross-sell / basket analysisCDP

Reputation

8/15

5/5 across 35 on Shopify directoryawards and community footprintsource ↗

Track record

11/15

since 2010 (16 years)team ~55-70

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#5 AWA Digital

CRO

London, UK · E-commerce CRO / experimentation · awa-digital.com · Founded 2009

64/100

Rank #5 of 20 in the UK

AWA Digital: London e-commerce CRO specialist since 2009 with offices on three continents; co-authored the bestselling Kogan Page book 'E-commerce Website Optimization'.

Why AWA Digital ranks #5 in the UK: Deep veteran track record and enterprise-grade cases (Canon Europe across 13 territories at 1,200% ROI; 2x CRO Agency of the Year). No visible review presence is the main deduction.

Score composition64 of 100 pts

−36

Results

27/30

Canon Europe: CRO in 13 territories, 1,200% ROI2x CRO Agency of the Yearbestselling CRO booksource ↗

Specialization

17/20

2x CRO Agency of the Year

Data sophistication

6/20Not yet verified

Evidence found:structured testing+4attribution+2No public evidence:segmentation / RFMpredictive LTVcross-sell / basket analysisCDP

Reputation

5/15

no reviews found publiclyawards and community footprint

Track record

9/15

since 2009 (17 years)team senior team

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#6 PAASE

Email / SMS

Milton Keynes area, UK · AI/data-driven email & SMS retention · paase.co.uk · Founded 2019

63/100

Rank #6 of 20 in the UK

PAASE: Milton Keynes-area retention agency and the first Klaviyo Elite Master headquartered in EMEA, positioning around AI and predictive data-driven email/SMS.

Why PAASE ranks #6 in the UK: Top-tier specialization and genuine predictive/LTV work (Okanui +233% automated revenue), but a thin public reputation footprint - few reviews, little community presence - keeps it behind Underground Ecom.

Score composition63 of 100 pts

−37

Results

27/30

Okanui +233% automated revenuefirst EMEA-based Klaviyo Elite Mastersource ↗

Specialization

20/20

Klaviyo Master Elite (first in EMEA)

Data sophistication

8/20Not yet verified

Evidence found:segmentation / RFM+4predictive LTV+4No public evidence:cross-sell / basket analysisstructured testingattributionCDP

Reputation

3/15

no reviews found publiclyawards and community footprint

Track record

5/15

since 2019 (7 years)team unknown

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#7 Enchant Agency

Email / SMS▲ 2

London, UK · Email/CRM lifecycle, Klaviyo migrations · enchantagency.com · Founded 2015

61/100

Rank #7 of 20 in the UK

Enchant Agency: London email/CRM lifecycle agency founded in 2015 by global email speaker Philip Storey. Enchant Agency is a Klaviyo Master Platinum partner specializing in complex migrations and automation, and Klaviyo's 2026 EMEA UK & Ireland Partner of the Year.

Why Enchant Agency ranks #7 in the UK: Enchant Agency now has the awards and the reviews (Klaviyo UKI Partner of the Year 2026, 5.0 on Clutch), but the results pillar still rests on two homepage numbers: there is no case-study page, so Bohomoon's +1000% email revenue and Self Portrait's +390% have nothing written up behind them.

Score composition61 of 100 pts

−39

Results

19/30

Klaviyo 2026 EMEA UK & Ireland Partner of the YearBohomoon email revenue +1000% over 3 yearsSelf Portrait email revenue +390%

Specialization

17/20

Klaviyo Master Platinum

Data sophistication

10/20Not yet verified

Evidence found:segmentation / RFM+4structured testing+4attribution+2No public evidence:predictive LTVcross-sell / basket analysisCDP

Reputation

8/15

5/5 across 5 on Clutchawards and community footprintsource ↗

Track record

7/15

since 2015 (11 years)team ~30

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#8 Email Kong

Email / SMS▼ 1

London, UK · Klaviyo CRM & retention for DTC brands · emailkong.com · Founded 2021

60/100

Rank #8 of 20 in the UK

Email Kong: London Klaviyo-first retention agency for high-growth DTC brands, founded in 2021 by Bogdan Mihalache and Cynthia de Gelder. Runs email, SMS and CRM programs for 140+ brands, reports $58.2M in attributed revenue, and holds Klaviyo's Master Platinum tier.

Why Email Kong ranks #8 in the UK: Directory-verified Master Platinum tier and six named, numbered case studies, but every case reads off the same three-metric template and the deeper claims (predictive models, 500+ audits) have no public material behind them. Publishing one teardown of its testing or predictive segmentation work would lift the data pillar.

Score composition60 of 100 pts

−40

Results

25/30

Alma de Ace 213% returning-customer revenue increase and 17.4x post-purchase flow revenueWhite River 33% Klaviyo-attributed revenue$58.2M attributed across 140+ DTC brandssource ↗

Specialization

17/20

Klaviyo Master Platinum (directory-verified)Klaviyo Partner Advisory Council seat (self-published)

Data sophistication

6/20Not yet verified

Evidence found:segmentation / RFM+4CDP+2No public evidence:predictive LTVcross-sell / basket analysisstructured testingattribution

Reputation

6/15

4.5/5 across 13 on Trustpilotawards and community footprintsource ↗

Track record

6/15

since 2021 (5 years)team boutique

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#9 Blend Commerce

CRO▼ 1

Stratford-upon-Avon, UK · Shopify CRO/CVO + Klaviyo retention · blendcommerce.com · Founded 2017

59/100

Rank #9 of 20 in the UK

Blend Commerce: Stratford-upon-Avon agency combining Shopify CVO (customer value optimization) with Klaviyo retention; named Global CRO Agency of the Year 2026.

Why Blend Commerce ranks #9 in the UK: The most balanced UK profile - results, RFM/testing/attribution evidence and awards all solid. A plain Klaviyo partner tier (no Master level) is what separates it from the top three.

Score composition59 of 100 pts

−41

Results

26/30

+61% subscription sign-ups, +14% store CVRGlobal CRO Agency of the Year 2026source ↗

Specialization

10/20

Klaviyo partnerGlobal CRO Agency of the Year 2026

Data sophistication

10/20Not yet verified

Evidence found:segmentation / RFM+4structured testing+4attribution+2No public evidence:predictive LTVcross-sell / basket analysisCDP

Reputation

7/15

no reviews found publiclyawards and community footprint

Track record

6/15

since 2017 (9 years)team in-house team

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#10 Melusine Studio

Email / SMS

London, UK · Email/SMS lifecycle for premium DTC · melusine.studio · Founded 2019

56/100

Rank #10 of 20 in the UK

Melusine Studio: Remote-first London studio (~15 people) running email/SMS lifecycle for premium DTC brands in English and French markets; clients include REFY and Daniel Wellington.

Why Melusine Studio ranks #10 in the UK: Klaviyo Platinum Master with good quantified work (+45% client turnover in a year). Young, with no review or community footprint yet - reputation is the growth area.

Score composition56 of 100 pts

−44

Results

26/30

Client turnover +45% in a yearclients incl. REFY, Daniel Wellingtonsource ↗

Specialization

17/20

Klaviyo Master Platinum

Data sophistication

8/20Not yet verified

Evidence found:segmentation / RFM+4structured testing+4No public evidence:predictive LTVcross-sell / basket analysisattributionCDP

Reputation

0/15

no reviews found publiclyawards and community footprint

Track record

5/15

since 2019 (7 years)team ~15

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#11 That Works Agency

CRO

Leeds, UK · Shopify CRO / design and build · thatworks.agency · Founded 2019

54/100

Rank #11 of 20 in the UK

That Works Agency: Leeds Shopify Premier Partner running conversion testing alongside theme builds, growth retainers and product imagery for DTC brands. Founded by Jordan Hill in 2019, now around 25 people working remotely, with client GMV self-reported above GBP 650m a year.

Why That Works Agency ranks #11 in the UK: A genuine always-on testing practice and the top Shopify partner tier, verified in the directory rather than self-claimed. The evidence thins out exactly where the rubric looks hardest: six of nine case studies carry no number, none show a baseline, a test count or a win rate, and there is no published work on segmentation, lifetime value or cross-sell. Putting per-test results and a review profile behind the existing wins would move this several places.

Score composition54 of 100 pts

−46

Results

25/30

49x ROI for DryRobe in six monthsGBP 20m+ new revenue attributed to split testingShopify Premier Partner since 2019source ↗

Specialization

14/20

Shopify Premier Partner since 2019 (directory-verified)certified Heatmap partner

Data sophistication

4/20Not yet verified

Evidence found:structured testing+4No public evidence:segmentation / RFMpredictive LTVcross-sell / basket analysisattributionCDP

Reputation

4/15

no reviews found publiclyawards and community footprint

Track record

7/15

since 2019 (7 years)team ~25

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#12 Converted

CRO

Sheffield & London, UK · CRO / experimentation (D2C, subscription) · converted.co.uk

51/100

Rank #12 of 20 in the UK

Converted: Sheffield/London CRO practice for D2C, e-commerce and subscription businesses, with 15+ years of experimentation experience.

Why Converted ranks #12 in the UK: Solid quantified results (+163% visitor-to-booking conversion), but an anonymous team page, no reviews and no certifications make it hard to verify depth - transparency would move it up.

Score composition51 of 100 pts

−49

Results

26/30

+163% visitor-to-booking conversion for London Travel Clinicsource ↗

Specialization

10/20

15+ years of CRO practice

Data sophistication

6/20Not yet verified

Evidence found:structured testing+4attribution+2No public evidence:segmentation / RFMpredictive LTVcross-sell / basket analysisCDP

Reputation

0/15

no reviews found publiclyawards and community footprint

Track record

9/15

team unknown

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#13 Shawfire Media

Email / SMS

Manchester, UK · Email/SMS retention for Shopify brands · shawfiremedia.com · Founded 2022

51/100

Rank #13 of 20 in the UK

Shawfire Media: Manchester email and SMS retention agency founded in 2022 by Jack Shaw, working with 7 and 8 figure Shopify brands in supplements, health and consumer tech. Klaviyo Gold Master partner reporting over $15m in attributable revenue across 75+ brands.

Why Shawfire Media ranks #13 in the UK: Four case studies that name the client and the number, including a channel share moving from 20% to 42% of revenue and holding above 35% for eighteen months. Credentials stop at Gold Master and there is no review profile anywhere, so the reputation pillar is carried entirely by a self-published regional award.

Score composition51 of 100 pts

−49

Results

22/30

Dr. Shiba: email from 20% to 42% of total revenue in 90 days, held above 35% for 18 monthssource ↗

Specialization

14/20

Klaviyo Gold Master

Data sophistication

6/20Not yet verified

Evidence found:segmentation / RFM+4CDP+2No public evidence:predictive LTVcross-sell / basket analysisstructured testingattribution

Reputation

3/15

no reviews found publiclyawards and community footprint

Track record

6/15

since 2022 (4 years)team ~10

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#14 Proof3

CRO

Shrewsbury, UK · Ecommerce CRO and experimentation, Magento and Shopify · proof3.co · Founded 2022

50/100

Rank #14 of 20 in the UK

Proof3: Shrewsbury based ecommerce growth agency spun out of Adobe Commerce Gold partner iWeb, running what it calls digital experience optimisation across Magento and Shopify retailers such as Autoglym, Goddiva, Tile Giant and Just Kampers.

Why Proof3 ranks #14 in the UK: Six client-named numbers including Autoglym revenue up 49% and Tile Giant conversion up 28.33%, backed by a real analytics and attribution practice. The catch is breadth: CRO sits alongside paid search, SEO and feed management, so several headline figures are not attributable to experimentation alone.

Score composition50 of 100 pts

−50

Results

25/30

Goddiva: conversion 1.2% to 2%, AOV +185%, revenue +212%source ↗

Specialization

10/20

Adobe Gold Certified via iWebShopify PartnerGoogle Marketing Platform certified

Data sophistication

6/20Not yet verified

Evidence found:structured testing+4attribution+2No public evidence:segmentation / RFMpredictive LTVcross-sell / basket analysisCDP

Reputation

2/15

no reviews found publiclyawards and community footprint

Track record

7/15

since 2022 (4 years)team 11-50

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#15 ElliotDigital

Email / SMS

London, UK · Email/SMS retention for DTC brands · elliotdigital.co.uk

49/100

Rank #15 of 20 in the UK

ElliotDigital: London email and SMS retention agency run by Elliot Scott as a small full-stack team covering strategy, copy, design and build. Klaviyo Platinum Master partner with UK DTC clients including SURREAL, Days Brewing, HUX and Cornelia James.

Why ElliotDigital ranks #15 in the UK: A high Klaviyo tier and a recognisable UK DTC client list, but only three published projects and one of them reports projected rather than realised revenue. Publishing five or six client-named results would move it past the agencies currently above it.

Score composition49 of 100 pts

−51

Results

21/30

NU-VEL: 1344% revenue growth in a year, email at 40% of monthly revenuesource ↗

Specialization

17/20

Klaviyo Platinum Master

Data sophistication

4/20Not yet verified

Evidence found:segmentation / RFM+4No public evidence:predictive LTVcross-sell / basket analysisstructured testingattributionCDP

Reputation

3/15

no reviews found publiclyawards and community footprint

Track record

4/15

team small, founder-led

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#16 Eastside Co

Email / SMS

Birmingham, UK · Shopify Plus builds with an ongoing Klaviyo email/retention practice · eastsideco.com · Founded 2012

44/100

Rank #16 of 20 in the UK

Eastside Co: Birmingham-founded Shopify Plus agency established in 2012, with offices in London, New York and Dubai and over 500 stores built. Its dedicated email team runs Klaviyo lifecycle programs, list growth and automation alongside the build practice.

Why Eastside Co ranks #16 in the UK: A 14-year Shopify track record undermined by unverifiable credentials: on the evidence cutoff date both its Klaviyo and Shopify directory profiles returned 404 and its Trustpilot profile has zero reviews, while its quantified email results are attributed to anonymous clients. Naming those clients and restoring the directory listings would roughly double its spec score overnight.

Score composition44 of 100 pts

−56

Results

20/30

Automated email at 6-9% of a client's monthly revenue (GBP 51,468 in three months)GBP 43,062 abandoned-cart recovery in two months500+ Shopify stores deliveredsource ↗

Specialization

6/20

Shopify Plus partner since 2012Klaviyo Platinum (self-claimeddirectory page not reachable)

Data sophistication

4/20Not yet verified

Evidence found:segmentation / RFM+4No public evidence:predictive LTVcross-sell / basket analysisstructured testingattributionCDP

Reputation

3/15

no reviews found publiclyawards and community footprint

Track record

11/15

since 2012 (14 years)team ~50-70

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#17 PM Digital

CRO

Northern Ireland (remote), UK · Shopify CRO for 7-9 figure DTC brands · www.pmdigitaldesign.com · Founded 2022

41/100

Rank #17 of 20 in the UK

PM Digital: Northern Ireland remote-first team (~16) doing Shopify CRO for 7-to-9-figure DTC brands, with an avatar/awareness-level parallel testing system and a public CRO learning hub.

Why PM Digital ranks #17 in the UK: Interesting methodology and real numbers (Ripley Rader GBP 1.5m+ revenue, +22% RPV), but credentials are self-stated and there's no third-party review presence yet.

Score composition41 of 100 pts

−59

Results

20/30

Ripley Rader: GBP 1.5m+ revenue, +22% revenue per visitoravatar-segmented parallel testing system

Specialization

6/20

Shopify Partner (self-stated)CRO Learning Hub

Data sophistication

10/20Not yet verified

Evidence found:structured testing+4attribution+2segmentation / RFM+4No public evidence:predictive LTVcross-sell / basket analysisCDP

Reputation

2/15

no reviews found publiclyawards and community footprint

Track record

3/15

since 2022 (4 years)team ~16

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#18 Browser to Buyer

CRO

London, UK · Full-service ecommerce CRO · browsertobuyer.com · Founded 2016

41/100

Rank #18 of 20 in the UK

Browser to Buyer: London full-service e-commerce CRO agency led by Dave Gowans, formerly of Conversion.com; Convert.com certified partner.

Why Browser to Buyer ranks #18 in the UK: Credible pedigree and strong claims (average +30% CVR in six months, minimum 10x ROI), but claims are aggregate and unverified - itemized case studies would substantially raise the results score.

Score composition41 of 100 pts

−59

Results

18/30

Avg +30% CVR within 6 months, min 10x ROI claimed+GBP 1m sales in year one for a clientsource ↗

Specialization

14/20

Convert.com certified partner

Data sophistication

6/20Not yet verified

Evidence found:structured testing+4attribution+2No public evidence:segmentation / RFMpredictive LTVcross-sell / basket analysisCDP

Reputation

1/15

no reviews found publiclyawards and community footprint

Track record

2/15

since 2016 (10 years)team founder-led

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#19 Customers Who Click

CRO

London, UK · Performance-based CRO for ecommerce/DTC · customerswhoclick.com

36/100

Rank #19 of 20 in the UK

Customers Who Click: London performance-based CRO shop for e-commerce/DTC founded by Will Laurenson, who hosts the Customers Who Click podcast; offers a $100k revenue guarantee model.

Why Customers Who Click ranks #19 in the UK: The guarantee model and content presence are distinctive, but there is minimal verifiable evidence: no reviews, no certifications, and case results shown without client names or context.

Score composition36 of 100 pts

−64

Results

18/30

A/B test wins of +45% and +70%$100k revenue guarantee modelCRO podcast + newslettersource ↗

Specialization

4/20

No formal certificationsworks on a performance-fee model

Data sophistication

6/20Not yet verified

Evidence found:structured testing+4attribution+2No public evidence:segmentation / RFMpredictive LTVcross-sell / basket analysisCDP

Reputation

5/15

no reviews found publiclyawards and community footprint

Track record

3/15

team <10

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#20 Sendfluence

Email / SMS

London, UK · Email/SMS lifecycle, performance-fee model · sendfluence.co.uk · Founded 2024

34/100

Rank #20 of 20 in the UK

Sendfluence: London Klaviyo agency running email/SMS lifecycle on a performance-fee pricing model, part of Fluence Collective.

Why Sendfluence ranks #20 in the UK: Three named, numbered case studies are now live, a real step up from none, but the Klaviyo directory entry is unreachable so the partner tier is a self-claim, and the review presence is still near zero. Restoring the directory listing and collecting reviews would move it fastest.

Score composition34 of 100 pts

−66

Results

20/30

God Save Queens: 83% email revenue increaseBenny's of London: 47.95% of website revenue from emailFLOC Brewing: 38.56% of website revenue from emailsource ↗

Specialization

6/20

Klaviyo Partner (self-claimeddirectory entry not reachable)

Data sophistication

4/20Not yet verified

Evidence found:segmentation / RFM+4No public evidence:predictive LTVcross-sell / basket analysisstructured testingattributionCDP

Reputation

2/15

4.5/5 across 1 on Googleawards and community footprint

Track record

2/15

since 2024 (2 years)team small, founder-led

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Missing from this list?

—/100

#? · unclaimed

Suggest an agency for the next monthly edition (your own counts). We research and score every candidate against the same public rubric; suggesting never buys a spot.

United States ranking →DACH ranking →

03 · Methodology

How agencies are scored

Every agency is scored 0-100 across five pillars from publicly verifiable evidence collected in October 2026. Evidence is weighted by tier: independently verified beats self-published, self-published beats claimed. The weighting is ours and deliberately favors data-driven operators; we publish the full rubric so you can disagree with it.

The Data Sophistication pillar is scored from public claims until verified. Earning the ✓ Verified Data-Driven badge means showing the data work behind the listing: a case study or work example we validate by hand, or one free Affinsy analysis on a client store.

Spotted something factually wrong on a listing? Any agency can ask for a correction: corrections ship with the next edition, they are free, and they change nothing about the score.

Proven results

Quantified case studies: email revenue share, LTV, CVR, repeat rate. Volume and standout bonuses on top of an evidence base score.

Specialization

Klaviyo partner tier (Elite > Master Platinum > Master Gold > Platinum > Partner) or CRO-platform credentials. Self-claimed expertise scores low.

Data sophistication

Segmentation / RFM, predictive LTV, cross-sell / basket analysis, structured testing, attribution, CDP. Scored from each agency's public claims until verified with real evidence.

Reputation

Third-party review volume and rating, industry awards, community footprint.

Track record

Years operating and client volume in e-commerce retention or CRO.

Excluded during sourcing: platform and tool vendors (Ebbo, ELAINE, Salesfire), absorbed agencies (Electriq), experimentation firms without an e-commerce-primary practice (Conversion.com, Cro Metrics, Speero, Daydot, Creative CX), generalists (WAUMEDIA, e-dialog), and agencies whose claims could not be verified (REO).

04 · Questions

Questions about this ranking

Which is the best retention and CRO agency in the UK in 2026?: Underground Ecom ranks #1 in Affinsy's October 2026 ranking of retention and CRO agencies in the UK, scoring 80 of 100, ahead of Get Better (#2, 69/100) and ConversionWise (#3, 66/100). All 20 agencies in the UK are scored on the same five pillars: proven results, specialization, data sophistication, reputation and track record.
Is a CRM agency the same as a retention agency in the UK?: Agencies in the UK usually sell this work as CRM. Here CRM means email and SMS lifecycle programmes, segmentation and repeat-purchase revenue, not the Salesforce or HubSpot sales-CRM implementation the same word means in the US and DACH. Affinsy's October 2026 ranking of the 20 best CRO, CRM and retention agencies in the UK scores all of them on the same five pillars, whatever each calls itself, led by Underground Ecom at 80/100.
How does Affinsy score retention and CRO agencies?: Each agency is scored 0-100 across five pillars: proven results (30 points), specialization (20), data sophistication (20), reputation (15) and track record (15). Scoring uses publicly verifiable evidence collected in October 2026, weighted by tier: independently verified evidence beats self-published, and self-published beats claimed. Underground Ecom scored 80, Get Better scored 69 and ConversionWise scored 66 in the UK.
Can an agency pay to be listed or to rank higher?: No. Rank position is never purchasable and no agency pays to appear in the ranking. Verification is free, and factual corrections to a listing never change the score.
What does the Verified Data-Driven badge mean?: It means the agency stood behind its listing with Affinsy directly and its data-capability claims held up to a hands-on review: a case study or work example, or one Affinsy analysis run on a client store. Underground Ecom carries the badge in the UK.
How often is the ranking updated?: Monthly. The current edition is October 2026, last updated October 6, 2026, and the next edition publishes November 4, 2026. Rankings are recomputed from evidence each edition, so positions move between editions.
How is this different from Clutch, G2 or other agency directories?: Review directories order agencies by the volume and rating of client reviews they collect. This ranking scores what an agency has publicly demonstrated: published results, specialization, data capability (segmentation, LTV modelling, basket analysis, structured testing), reputation and track record, each weighted by how independently the evidence can be verified. Review counts feed only the reputation pillar (15 of 100 points), so an agency cannot climb this list on reviews alone.
Which of these agencies specialize in Shopify stores?: ConversionWise (#3), Swanky (#4), Blend Commerce (#9), That Works Agency (#11), Shawfire Media (#13), Proof3 (#14), Eastside Co (#16) and PM Digital (#17) name Shopify or Shopify Plus in their published focus or case studies in the UK. Most agencies in the list work across Shopify, WooCommerce and Magento; this answer lists only the ones whose public material calls out Shopify specifically.
Which are the best Klaviyo agencies in the UK?: 12 of the 20 agencies in the UK reference Klaviyo in their published focus, partner status or case studies: Underground Ecom (#1), Get Better (#2), Swanky (#4), PAASE (#6), Enchant Agency (#7), Email Kong (#8), Blend Commerce (#9), Melusine Studio (#10), Shawfire Media (#13), ElliotDigital (#15), Eastside Co (#16) and Sendfluence (#20). The highest-scoring of them is Underground Ecom at 80/100.
Which cities are these agencies based in, and do they work with brands elsewhere in the UK?: Headquarters represented in the October 2026 edition: London; North Devon; Bristol; Exeter; Milton Keynes area; Stratford-upon-Avon; Leeds; Sheffield & London; Manchester; Shrewsbury; Birmingham; Northern Ireland (remote). Every agency in the list works remotely with e-commerce brands across the United Kingdom, so a brand in a city not listed here is not limited to local firms.

05 · Verification

Earn the Verified Data-Driven badge

Show the data work behind your listing: run a free analysis on one client store, or submit equivalent evidence. The badge lands in the next monthly edition.

Verify your listing →

Verification is free · Rank position is never purchasable