The best Klaviyo agencies in France

Intro

Generating revenue through email marketing is no longer a matter of sending generic newsletters. The e-commerce brands that perform in marketing automation rely on personalized flows, surgical segmentation and customer lifecycle scenarios that turn every interaction into recurring revenue.

But handing your CRM strategy to an external provider remains a gamble. Between generalist agencies that only scratch the surface and specialists who master every deliverability parameter, the gap in results can be considerable. A poor choice costs time, disengaged subscribers and email revenue left on the table.

This comparison examines six French agencies recognized for their command of the Klaviyo platform. Each has a distinct positioning, verifiable references and its own approach. The goal: to give you the concrete elements you need to identify the one that matches your CRM maturity and your growth ambitions.

Standard Ecom

Standard Ecom positions itself as an e-commerce CRM specialist capable of building tailored strategies for each brand. The agency focuses its expertise on advanced segmentation, automation and customer lifecycle optimization.

The results documented by the team speak for themselves: +30% revenue attributed to flows, a doubling of welcome flow performance and a 30% increase across total CRM revenue. These metrics reflect an approach firmly geared toward return on investment.

Three dedicated CRM Managers run the projects: Lou Dugua, Maëvane Flavigni and Théo Esteoulle. This setup guarantees a single point of contact per brand, able to track performance day to day and continuously adjust automation scenarios.

The agency is not limited to Klaviyo. It also advises on tool selection such as HubSpot or Salesforce depending on the client's technical maturity and existing architecture. This flexibility avoids forcing an unsuitable tool onto a brand that would not get the most out of it.

A free CRM diagnosis lets brands assess their growth potential before any commitment. It is a concrete entry point for those who want to measure the gap between their current setup and what an optimized CRM strategy could actually generate.

Ultrō

Founded in 2009 by Antoine Caillet and Thomas Le Mouellic, Ultrō holds a rating of 4.9/5 based on 25 client reviews. The agency operates out of Bordeaux and Clermont-Ferrand, giving it a solid regional presence outside Paris.

Its Klaviyo partner status is backed by technical compatibility with several CMS platforms: Shopify, Centra, WooCommerce and PrestaShop. This technical versatility allows it to work on varied e-commerce architectures without integration friction.

The La Rosée case study offers a concrete look at their methodology. Since 2020, Ultrō has supported this cosmetics brand with a full Klaviyo implementation, complex abandoned cart flows and dynamic pop-ups. The integration of a diagnostic questionnaire linked directly to Klaviyo segmentation illustrates a level of personalization that is rarely achieved.

The engagement covers a broad scope: initial setup, automation creation, overall CRM strategy and analytics through custom dashboards. Brands looking for a partner able to manage the entire email marketing chain will find a complete and structured offering with Ultrō.

Emailio

Emailio claims Gold Partner Klaviyo status and a radical positioning: no SEO, no Google Ads, no social media. The agency does nothing but e-commerce CRM through Klaviyo, full stop. This choice of exclusive specialization targets online stores generating between €50k and €500k per month with a minimum of 5,000 email contacts.

What concrete services does Emailio offer?

• CRM strategy, copywriting, design and integration in a single package
• High-performance flow architecture: abandoned cart, welcome series, post-purchase and winback
• Segmentation based on behavioral data rather than declarative criteria
• Full migration from Mailchimp, Brevo or Shopify Email

The agency promises visible results within 2 to 4 weeks of activating the first flows. This is a precise time commitment that reassures brands eager to see the impact on their revenue.

A free 30-minute no-commitment audit opens the door to an initial assessment. This quick format makes it possible to gauge the relevance of a partnership with Emailio before committing to a long-term collaboration.

ThirtyFive

ThirtyFive holds the highest certification level in this comparison: Master Elite Klaviyo. The agency works with more than 50 brands and posts a satisfaction score of 9.7/10 based on 50 reviews. On average, the CRM channel represents 35% of its clients' revenue.

The 15-person team assigns a dedicated CRM Manager to each brand. This setup echoes that of Standard Ecom, but ThirtyFive goes further by integrating complementary channels such as SMS marketing (open rate above 95%) and WhatsApp marketing.

The WhatsApp channel in particular delivers remarkable performance at ThirtyFive: a 98% open rate and a 15x ROI. These figures position the agency as a player able to diversify touchpoints well beyond classic email.

The agency does not confine itself to Klaviyo. It also masters Braze and Splio, making it a relevant partner for brands considering migrating to or combining several marketing automation tools. A free CRM audit rounds out the introductory offer.

Modern Letter

Modern Letter draws on 10 years of digital marketing experience and a 4.9/5 rating built on 61 client reviews. The agency focuses exclusively on Klaviyo and targets B2C e-commerce brands, primarily those operating on Shopify.

What sets Modern Letter apart is speed of execution. Several clients report implementations completed in under a week. For a brand losing revenue every day without active flows, this operational responsiveness is a decisive advantage.

The engagement includes a training component rarely offered by competitors. Modern Letter provides personalized Klaviyo training to make internal teams autonomous. The 30-minute strategic diagnosis calls and weekly KPI tracking complete a setup designed for transparency.

A few limitations are worth noting. The agency remains single-platform (Klaviyo only), displays no visible certification and does not disclose its pricing. For brands seeking a certified or multi-CRM partner, this positioning may be a drawback.

Horizon

Horizon stands out with a positioning that straddles e-commerce and lead generation, whereas most of the agencies in this comparison limit themselves to B2C. The agency holds certified Klaviyo Partner status with privileged access to the platform's teams and resources.

The approach rests on three complementary pillars:

• Full technical management covering configuration, migrations and Shopify integrations
• A data-driven strategic vision to align CRM with business objectives
• An in-house creative studio for email design and operational production

This combination of technical, marketing and creative capabilities goes beyond simple campaign management. Horizon uses artificial intelligence tools and consolidates data to optimize performance in real time, which requires an above-average level of technical maturity.

The agency also handles migrations from Mailchimp and Klaviyo account creation from scratch. On the other hand, Horizon discloses neither its client count nor its pricing, and its CRM coverage remains almost exclusively centered on Klaviyo. Brands that need verifiable quantitative data before committing will find this lack of transparency frustrating.

FAQ

How do you choose the best Klaviyo agency for your e-commerce brand?

Start by assessing your current CRM maturity and your goals for the next 6 months. A brand just getting started on Klaviyo does not have the same needs as a store looking to optimize existing flows.

Next, check the agency's Klaviyo certification level and ask for verifiable case studies in your sector. A free audit, offered by several agencies, lets you test the relevance of the strategic recommendations before any financial commitment.

What budget should you plan for Klaviyo support in France?

Most specialized agencies do not publish a fixed price list. Rates vary depending on the volume of contacts, the number of flows to build and the level of support required.

Expect to pay generally between €1,500 and €5,000 per month for full CRM support including strategy, design and monitoring. The free initial audits offered by several agencies make it possible to obtain a quote tailored to your situation with no budget surprises.

What is the difference between a Klaviyo Partner and a Klaviyo Master Elite?

Klaviyo assigns its certification levels based on the number of clients managed, the volume of revenue generated and the quality of results achieved. A standard Partner demonstrates baseline expertise, while a Master Elite sits at the top of the hierarchy.

Master Elite status grants access to exclusive resources, priority support from Klaviyo and enhanced visibility in the official directory. This criterion remains a reliable indicator of the experience an agency has accumulated on the platform.

How long does it take to see results with Klaviyo?

The first automated flows (welcome series, abandoned cart) begin generating revenue as soon as they are activated. Some agencies report measurable results within 2 to 4 weeks of launch.

Fully optimizing a CRM strategy, however, takes 3 to 6 months. The gains build up gradually through continuous A/B testing, refined segmentation and the enrichment of behavioral data collected over time.

Do you need to be on Shopify to work with a Klaviyo agency?

Klaviyo integrates natively with Shopify, WooCommerce, Magento and PrestaShop. Most French agencies handle these multi-CMS integrations without any particular technical difficulty.

Shopify remains the most common CMS among these agencies' clients, which explains their natural affinity with it. But a store on WooCommerce or PrestaShop will also find providers able to configure Klaviyo and make full use of its automation features on those platforms.