Affinsy Rankings · July 2026 edition

Best Retention & CRO Agencies in the US, 2026

The 15 strongest retention, lifecycle and CRO agencies we found for e-commerce brands in the US, 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.

Evidence collected July 2026 · Updated July 15, 2026

01 · The ranking

Email / SMS lifecycleCRO / experimentationFull retention

Debut edition · rank movement appears from the next refresh

#176/ 100

The Good

CRO

Portland, OR, US · CRO / digital experience optimization · thegood.com · Founded 2009

Portland-based conversion firm working exclusively on digital experience optimization for e-commerce and consumer brands since 2009. Founder Jon MacDonald has written three books on conversion and hosts the Drive & Convert podcast.

Why this rank: The strongest results portfolio in the US list: 35+ published case studies with hard numbers (Snow Peak +149% online revenue, 16:1 average ROI claimed) plus the deepest third-party reputation (270 reviews). Only the absence of lifecycle/email services keeps it from a higher data-capability score.

Results

28/30

Specialization

17/20

Data sophistication

7/20

Reputation

13/15

Track record

11/15

How this score breaks down

Results28/30

Documented outcomes: +149% online revenue for Snow Peak; 16:1 avg ROI; 35+ case studies; 3 books by founder

Specialization17/20

Credentials: Top-rated CRO firm (Clutch), Drive & Convert podcast

Data sophistication7/20

Evidenced: structured testing (+4), attribution (+3) · not evidenced: segmentation / RFM, predictive LTV, CDP Not yet verified

Reputation13/15

Reviews: 4.9/5 across 270 on Clutch, plus awards and community footprint

Track record11/15

Operating: since 2009 (17 years), team ~27

Top-rated CRO firm (Clutch), Drive & Convert podcast·4.9/5 · 270 reviews (Clutch)Not yet verifiedVerify or update this listing →

#271/ 100

Invesp

CRO

Chicago, IL, US · CRO / experimentation · invespcro.com · Founded 2006

Chicago CRO pioneer founded 2006 by Khalid Saleh and Ayat Shukairy, who co-wrote the book 'Conversion Optimization'. Runs senior 7-person pods per client and its own testing tool, FigPii.

Why this rank: Twenty years of pure CRO practice and Clutch's #1 CRO agency worldwide five years running (2021-2025). Quantified cases like Stoneside's $1M+ added sales anchor the results score; a narrower data stack (no CDP/LTV evidence) is the main gap.

Results

26/30

Specialization

17/20

Data sophistication

7/20

Reputation

10/15

Track record

11/15

How this score breaks down

Results26/30

Documented outcomes: Clutch #1 CRO agency worldwide 5 consecutive years; Stoneside $1M+ added sales

Specialization17/20

Credentials: Clutch #1 CRO worldwide 2021-2025; own tool FigPii

Data sophistication7/20

Evidenced: structured testing (+4), attribution (+3) · not evidenced: segmentation / RFM, predictive LTV, CDP Not yet verified

Reputation10/15

Reviews: 4.9/5 across 30 on Clutch, plus awards and community footprint

Track record11/15

Operating: since 2006 (20 years), team ~20-50

Clutch #1 CRO worldwide 2021-2025; own tool FigPii·4.9/5 · 30 reviews (Clutch)Not yet verifiedVerify or update this listing →

#367/ 100

Essence of Email

Email / SMS

Houston, TX, US · Email/SMS lifecycle retention · essenceofemail.com · Founded 2014

Houston email boutique (~30 people) doing full lifecycle retention: Klaviyo flows, SMS, ESP migrations and deliverability. Klaviyo Master Gold with Postscript and Stamped partnerships.

Why this rank: Publishes some of the most extreme documented outcomes in the category (Frame Destination +9,245% email revenue; Oransi $624K in under 3 months) and evidences the fullest data stack of any US email shop, including RFM and LTV modeling. Near-zero third-party reviews hold the reputation score down.

Results

27/30

Specialization

14/20

Data sophistication

17/20

Reputation

1/15

Track record

8/15

How this score breaks down

Results27/30

Documented outcomes: Frame Destination +9,245% email revenue; Oransi $624K email revenue in <3 months

Specialization14/20

Credentials: Klaviyo Master Gold; Postscript/Stamped partners

Data sophistication17/20

Evidenced: segmentation / RFM (+5), structured testing (+4), attribution (+3), predictive LTV (+5) · not evidenced: CDP Not yet verified

Reputation1/15

Reviews: none found publicly; scored on awards and community footprint

Track record8/15

Operating: since 2014 (12 years), team ~30

Klaviyo Master Gold; Postscript/Stamped partners·No public reviews foundNot yet verifiedVerify or update this listing →

#465/ 100

Rejoiner

Retention

Newport, RI, US · Email/SMS/direct-mail retention (own ESP) · rejoiner.com · Founded 2011

Rhode Island retention shop running email, SMS and direct mail on its own proprietary ESP, combining software with a fully managed service team since 2011.

Why this rank: Rare predictive/LTV depth and solid quantified outcomes (AuthenTEAK +22% revenue; Triumph +40% YoY email revenue). Scores as a specialist rather than through Klaviyo tiers, since it runs its own platform - a structural cap on the specialization pillar.

Results

26/30

Specialization

12/20

Data sophistication

13/20

Reputation

5/15

Track record

9/15

How this score breaks down

Results26/30

Documented outcomes: AuthenTEAK revenue +22% to $2M+; Triumph email revenue +40% YoY; own platform + managed service

Specialization12/20

Credentials: Proprietary retention platform + managed service

Data sophistication13/20

Evidenced: segmentation / RFM (+5), predictive LTV (+5), attribution (+3) · not evidenced: structured testing, CDP Not yet verified

Reputation5/15

Reviews: 5/5 across 14 on Clutch, plus awards and community footprint

Track record9/15

Operating: since 2011 (15 years), team 10-49

Proprietary retention platform + managed service·5/5 · 14 reviews (Clutch)Not yet verifiedVerify or update this listing →

#565/ 100

Fuel Made

Email / SMS

Seattle, WA, US · Klaviyo lifecycle + Shopify CRO · fuelmade.com · Founded 2010

Seattle agency pairing Klaviyo lifecycle marketing with Shopify CRO and design, operating since 2010. One of roughly 30 Klaviyo Master Elite partners among 6,500+ worldwide.

Why this rank: Elite-tier specialization plus a perfect 5.0 across 26 Clutch reviews. Publishes aggregate claims (email drives 20-40% of client revenue) rather than a deep library of itemized case studies, which caps the results pillar.

Results

19/30

Specialization

20/20

Data sophistication

9/20

Reputation

9/15

Track record

8/15

How this score breaks down

Results19/30

Documented outcomes: Email drives 20-40% of client revenue; Klaviyo Master Elite (~30 of 6,500+ partners)

Specialization20/20

Credentials: Klaviyo Master Elite

Data sophistication9/20

Evidenced: segmentation / RFM (+5), structured testing (+4) · not evidenced: predictive LTV, attribution, CDP Not yet verified

Reputation9/15

Reviews: 5/5 across 26 on Clutch, plus awards and community footprint

Track record8/15

Operating: since 2010 (16 years), team 10-49

Klaviyo Master Elite·5/5 · 26 reviews (Clutch)Not yet verifiedVerify or update this listing →

#663/ 100

Flowium

Email / SMS

New York, NY, US · Email/SMS lifecycle (Klaviyo full-service) · flowium.com · Founded 2017

New York full-service Klaviyo agency founded 2017 by Andriy Boychuk; runs the Email Einstein podcast and a Klaviyo training course, and sits on Klaviyo's 2026 Partner Advisory Council.

Why this rank: Master Elite tier, strong reviews (4.9/23) and one of the best community footprints in the list. Public case studies are lighter on hard numbers than direct peers, which limits the results score.

Results

18/30

Specialization

20/20

Data sophistication

9/20

Reputation

11/15

Track record

5/15

How this score breaks down

Results18/30

Documented outcomes: Klaviyo Master Elite; 2026 Klaviyo Partner Advisory Council; Email Einstein podcast

Specialization20/20

Credentials: Klaviyo Master Elite

Data sophistication9/20

Evidenced: segmentation / RFM (+5), structured testing (+4) · not evidenced: predictive LTV, attribution, CDP Not yet verified

Reputation11/15

Reviews: 4.9/5 across 23 on Clutch, plus awards and community footprint

Track record5/15

Operating: since 2017 (9 years), team 50-249

Klaviyo Master Elite·4.9/5 · 23 reviews (Clutch)Not yet verifiedVerify or update this listing →

#761/ 100

Surefoot

CRO

Portland, OR, US · CRO / experimentation + user research · surefoot.me · Founded 2017

Portland-based CRO and user-research boutique (~10-15 people) running experimentation on Convert, Adobe Target, Dynamic Yield and Amplitude stacks.

Why this rank: Consistent, honest quantified test results (Peak Design +17% AOV; BioLite +18% transactions) and credible multi-platform certification. Small review base and boutique scale keep it mid-table.

Results

26/30

Specialization

14/20

Data sophistication

10/20

Reputation

5/15

Track record

6/15

How this score breaks down

Results26/30

Documented outcomes: Peak Design free-shipping test +17% AOV; BioLite checkout +18% transactions

Specialization14/20

Credentials: Convert, Adobe Target, Dynamic Yield, Amplitude

Data sophistication10/20

Evidenced: structured testing (+4), attribution (+3), CDP (+3) · not evidenced: segmentation / RFM, predictive LTV Not yet verified

Reputation5/15

Reviews: 5/5 across 6 on Clutch, plus awards and community footprint

Track record6/15

Operating: since 2017 (9 years), team ~10-15

Convert, Adobe Target, Dynamic Yield, Amplitude·5/5 · 6 reviews (Clutch)Not yet verifiedVerify or update this listing →

#861/ 100

Stimulate Agency

Retention

St. Petersburg, FL, US · Full retention (email/SMS/direct mail/loyalty) · stimulate.agency · Founded

Florida full-retention boutique covering email, SMS, direct mail, loyalty and subscriptions, with two dedicated experts per client account.

Why this rank: Documented outcomes are excellent - Skinmedix email revenue from 12% to 45% of sales in 90 days, +47% LTV - and the data capability evidence (RFM, testing, attribution, LTV) is among the broadest. A young, small profile with few reviews limits reputation and track record.

Results

24/30

Specialization

12/20

Data sophistication

17/20

Reputation

5/15

Track record

3/15

How this score breaks down

Results24/30

Documented outcomes: Skinmedix: email revenue 12% to 45% of sales in 90 days; +47% LTV

Specialization12/20

Credentials: Klaviyo Platinum

Data sophistication17/20

Evidenced: segmentation / RFM (+5), structured testing (+4), attribution (+3), predictive LTV (+5) · not evidenced: CDP Not yet verified

Reputation5/15

Reviews: 4.9/5 across 5 on Clutch, plus awards and community footprint

Track record3/15

Operating: since (2026 years), team boutique

Klaviyo Platinum·4.9/5 · 5 reviews (Clutch)Not yet verifiedVerify or update this listing →

#960/ 100

GrowthHit

CRO

Seattle, WA, US · CRO-led growth for DTC/ecommerce · growthhit.com · Founded 2016

Seattle CRO-led growth team (40+ operators) for 7-to-8-figure DTC brands; founder Jim Huffman wrote 'The Growth Marketer's Playbook' and teaches growth for Fortune 500s.

Why this rank: Big verified aggregates ($250M+ client revenue, 1,000+ experiments) and strong reviews (4.9/20), but few itemized public case studies - aggregate claims score lower than named, numbered cases under our rules.

Results

19/30

Specialization

10/20

Data sophistication

12/20

Reputation

11/15

Track record

8/15

How this score breaks down

Results19/30

Documented outcomes: $250M+ client revenue across 1,000+ experiments; 88% of clients hit sales goals

Specialization10/20

Credentials: Certified Klaviyo partner; 'Growth Marketer's Playbook' author

Data sophistication12/20

Evidenced: structured testing (+4), attribution (+3), segmentation / RFM (+5) · not evidenced: predictive LTV, CDP Not yet verified

Reputation11/15

Reviews: 4.9/5 across 20 on Clutch, plus awards and community footprint

Track record8/15

Operating: since 2016 (10 years), team 40+

Certified Klaviyo partner; 'Growth Marketer's Playbook' author·4.9/5 · 20 reviews (Clutch)Not yet verifiedVerify or update this listing →

#1053/ 100

Conversion Fanatics

CRO

Austin, TX, US · CRO / A-B testing + PPC · conversionfanatics.com · Founded 2014

Austin CRO and A/B testing agency (founded 2014, now part of Fusion92) with thousands of tests run and a published book, 'Conversion Fanatic'.

Why this rank: A 46% test win rate and standout cases like ButcherBox +40% monthly CVR, but no premium platform certifications, which caps the specialization pillar.

Results

19/30

Specialization

10/20

Data sophistication

7/20

Reputation

9/15

Track record

8/15

How this score breaks down

Results19/30

Documented outcomes: ButcherBox: one A/B test +40% monthly CVR; 46% win rate across thousands of tests

Specialization10/20

Credentials: Clutch 1000; book 'Conversion Fanatic'

Data sophistication7/20

Evidenced: structured testing (+4), attribution (+3) · not evidenced: segmentation / RFM, predictive LTV, CDP Not yet verified

Reputation9/15

Reviews: 4.8/5 across 16 on Clutch, plus awards and community footprint

Track record8/15

Operating: since 2014 (12 years), team boutique

Clutch 1000; book 'Conversion Fanatic'·4.8/5 · 16 reviews (Clutch)Not yet verifiedVerify or update this listing →

#1151/ 100

InboxArmy

Email / SMS

Grapevine, TX, US · Full-service email agency (50+ ESPs) · inboxarmy.com · Founded 2016

Texas email production powerhouse: 120-150 marketers covering strategy, design, deliverability and operations across 50+ ESPs, from Klaviyo to Salesforce Marketing Cloud.

Why this rank: Scale and social proof are strong (4.9/71 on Clutch; RCJuice +400% monthly revenue from automations). ESP-agnostic generalism means no elite Klaviyo tier and thinner strategic data evidence than retention pure-plays.

Results

19/30

Specialization

10/20

Data sophistication

3/20

Reputation

9/15

Track record

10/15

How this score breaks down

Results19/30

Documented outcomes: RCJuice cart-abandonment automations +400% monthly revenue; 120-150 marketers

Specialization10/20

Credentials: Certified Klaviyo Partner; SFMC certified

Data sophistication3/20

Evidenced: attribution (+3) · not evidenced: segmentation / RFM, predictive LTV, structured testing, CDP Not yet verified

Reputation9/15

Reviews: 4.9/5 across 71 on Clutch, plus awards and community footprint

Track record10/15

Operating: since 2016 (10 years), team 120-150

Certified Klaviyo Partner; SFMC certified·4.9/5 · 71 reviews (Clutch)Not yet verifiedVerify or update this listing →

#1251/ 100

Prismfly

CRO

Miami, FL, US · CRO + Shopify + lifecycle email/SMS · prismfly.com · Founded 2020

Miami-based (distributed) agency combining CRO/experimentation with Shopify builds and lifecycle email/SMS. Klaviyo Platinum, Shopify Plus and Recharge partner.

Why this rank: Impressive client outcomes (Simple Modern doubled D2C sales in a year) and a genuine multi-disciplinary stack, but founded 2020 with no public reviews yet - track record and reputation will catch up.

Results

19/30

Specialization

12/20

Data sophistication

10/20

Reputation

4/15

Track record

6/15

How this score breaks down

Results19/30

Documented outcomes: Simple Modern doubled D2C sales in 1 year; Luxy Hair +35% CVR

Specialization12/20

Credentials: Klaviyo Platinum; Shopify Plus, Recharge partner

Data sophistication10/20

Evidenced: structured testing (+4), attribution (+3), CDP (+3) · not evidenced: segmentation / RFM, predictive LTV Not yet verified

Reputation4/15

Reviews: none found publicly; scored on awards and community footprint

Track record6/15

Operating: since 2020 (6 years), team 10-49

Klaviyo Platinum; Shopify Plus, Recharge partner·No public reviews foundNot yet verifiedVerify or update this listing →

#1345/ 100

Growth Rock

CRO

San Jose, CA, US · Ecommerce-only CRO & A/B testing boutique · growthrock.co · Founded

Bay Area boutique doing 100% e-commerce CRO and A/B testing for 7-to-9-figure stores; publishes original UX research (mobile checkout, navigation studies) widely cited in CRO circles.

Why this rank: Rigorous, statistically honest published tests (+19% orders at 99.9% significance) and respected research, but no certifications, no third-party reviews and boutique scale - evidence quality is high, evidence volume is low.

Results

26/30

Specialization

4/20

Data sophistication

7/20

Reputation

2/15

Track record

6/15

How this score breaks down

Results26/30

Documented outcomes: +19% orders at 99.9% significance from free-shipping test; original ecommerce UX research widely cited in CRO circles

Specialization4/20

Credentials: No certs found; 100% ecommerce CRO focus

Data sophistication7/20

Evidenced: structured testing (+4), attribution (+3) · not evidenced: segmentation / RFM, predictive LTV, CDP Not yet verified

Reputation2/15

Reviews: none found publicly; scored on awards and community footprint

Track record6/15

Operating: since (2026 years), team <10

No certs found; 100% ecommerce CRO focus·No public reviews foundNot yet verifiedVerify or update this listing →

#1439/ 100

Sticky Digital

Email / SMS

San Diego, CA, US · Email/SMS lifecycle + retention · stickydigital.io · Founded

San Diego email/SMS retention shop for Shopify DTC brands, twice named Yotpo's #1 Retention Marketing Agency in North America (2023, 2024).

Why this rank: The Yotpo awards and bold aggregate claims (email/SMS driving 35-50% of client store revenue) are promising, but almost nothing is publicly verifiable: no case-study library, no reviews, self-stated Platinum tier.

Results

18/30

Specialization

12/20

Data sophistication

3/20

Reputation

4/15

Track record

2/15

How this score breaks down

Results18/30

Documented outcomes: Clients attribute 35-50% of store revenue to email/SMS; Yotpo #1 Retention Agency NA 2023 & 2024

Specialization12/20

Credentials: Klaviyo Platinum (self-stated); Yotpo award winner

Data sophistication3/20

Evidenced: attribution (+3) · not evidenced: segmentation / RFM, predictive LTV, structured testing, CDP Not yet verified

Reputation4/15

Reviews: none found publicly; scored on awards and community footprint

Track record2/15

Operating: since (2026 years), team unknown

Klaviyo Platinum (self-stated); Yotpo award winner·No public reviews foundNot yet verifiedVerify or update this listing →

#1537/ 100

Ragnarok

Email / SMS

New York, NY, US · Email/SMS lifecycle + CRM/MarTech · ragnarokmarketing.com · Founded 2012

New York lifecycle/CRM agency (~35 people, now part of Apply Digital) implementing Klaviyo, Braze and Iterable for brands like Allbirds, UNTUCKit and Birchbox.

Why this rank: Klaviyo Master Gold since 2018 and a blue-chip client roster, but no published performance numbers and no reviews - the weakest public evidence base in the US list. A few published case studies would move it significantly.

Results

12/30

Specialization

14/20

Data sophistication

3/20

Reputation

1/15

Track record

7/15

How this score breaks down

Results12/30

Documented outcomes: Klaviyo Master Gold since 2018; clients Allbirds, UNTUCKit, Birchbox (no published numbers)

Specialization14/20

Credentials: Klaviyo Master Gold; Braze/Iterable implementations

Data sophistication3/20

Evidenced: CDP (+3) · not evidenced: segmentation / RFM, predictive LTV, structured testing, attribution Not yet verified

Reputation1/15

Reviews: none found publicly; scored on awards and community footprint

Track record7/15

Operating: since 2012 (14 years), team ~35

Klaviyo Master Gold; Braze/Iterable implementations·No public reviews foundNot yet verifiedVerify or update this listing →

United Kingdom ranking →DACH ranking →

02 · Methodology

How agencies are scored

Every agency is scored 0-100 across five pillars from publicly verifiable evidence collected in July 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. Verification means showing the data work behind the listing: the fastest route is one free Affinsy analysis on a client store, but any credible evidence counts. Verified listings carry the ✓ Verified Data-Driven badge from the next monthly edition.

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, structured testing program, 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).

03 · 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 or update your listing →

Verification is free · Rank position is never purchasable