How to choose your SEO agency in 2026

In short:

1. Choosing an SEO agency starts with a brief: business goals, scope (technical, content, link building, GEO) and a budget that can be sustained over time.
2. Nine criteria make the difference, grouped into three families: expertise, proof and the working relationship.
3. No agency can guarantee the top position on Google: a promise of that kind is enough to rule out a provider.

Knowing how to choose your SEO agency avoids the most expensive mistake in organic search: losing a full year with a provider that fits neither the site’s stakes nor the level of competition in its market. Hundreds of agencies now claim the same expertise, from freelancers to integrated groups, with very different methods, deliverables and levels of transparency. This guide brings together the criteria that make it possible to compare offers on verifiable elements, the questions to ask before signing and the signals that should raise a red flag.

Defining your needs before approaching an SEO agency

An agency can only be assessed against a precise need. Before the first meeting, a company benefits from putting three elements into a short brief: the business goals expected from organic search (leads, online sales, visibility on a topic), the scope of the engagement and the budget available over time.

Organic search rests on three interdependent pillars: technical SEO (crawling, indexing, performance, structured data), content and semantics, and authority, built through link building and digital PR. Visibility in generative engines, ChatGPT, Perplexity, Gemini or Google’s AI Overviews, now comes on top of that. An e-commerce site with several thousand pages does not have the same priorities as a service SME trying to rank locally: the starting point differs, and so does the right agency.

Time also needs to be set out from the start. SEO produces gradual effects that show over several months: a budget sized for a single quarter does not allow an agency to be judged, let alone a lasting position to be built. A narrower scope held over time is better than a broad scope abandoned after three months.

Expertise criteria: what an SEO agency must master

An explicit method that starts with an audit

A serious agency presents its method before its results. The approach follows a documented logic: an SEO audit of the site and its competitors, prioritization of workstreams, implementation, measurement, adjustments. Asking for the details of that method, step by step, quickly reveals a team’s real level: how the audit is run, with which tools, and how its conclusions turn into a prioritized action plan. A good agency also asks many questions about the company’s market, competitors and customers: it is a sign that it wants to understand before selling.

Coverage of the three pillars of SEO

Organic performance never depends on a single lever. An agency that only handles technical work leaves aside the content that captures search intent, and an agency that only produces content runs into a poorly crawled site with no authority. It is worth checking that the team has technical, editorial and link building profiles, in house or with identified partners. On authority, the link strategy deserves precise questions: types of sites targeted, how links are obtained, anchor choices. The ranking of link building agencies details the practices that set serious players apart.

Taking GEO and generative engines into account

Search is no longer limited to ten blue links. AI Overviews have been live in France since 22 July 2026, and a growing share of information journeys now goes through conversational assistants. An SEO agency must now be able to explain how it works on getting a brand cited in these answers, what GEO actually covers and how it measures that visibility. One that still sees the topic as a passing trend is preparing yesterday’s SEO.

Proof criteria: what an SEO agency can demonstrate

Verifiable results in a comparable context

Case studies with precise metrics are worth more than a wall of logos. The figures shown must be put in context: starting point, length of the engagement, level of competition in the market, actions carried out. A spectacular gain in an uncontested market proves little for a highly competitive industry. Whenever possible, a direct conversation with a current or former client remains the most reliable check, which is exactly what Google itself recommends.

Transparent methods that follow Google’s guidelines

So-called black hat practices, such as mass buying of low quality links, content produced at scale with no added value or cloaking, can bring quick gains followed by lasting penalties. Google’s spam policies explicitly prohibit them. A transparent agency explains every action, shares the list of changes made to the site and justifies its recommendations. There is nothing secret about SEO: a method that cannot be explained should not be bought.

Reporting tied to business goals

Good reporting is not just a table of rankings. It links the evolution of non-brand organic traffic, conversions and organic revenue to the actions carried out during the period, and proposes the next action plan. The company must also keep control of its data: the Google Search Console and analytics properties stay in its name, and the agency is invited to them, never the other way around. Asking for a sample report before signing makes it possible to judge an agency’s rigor in a few minutes.

Relationship criteria: how the SEO agency works day to day

A dedicated contact and an identified team

SEO is built over time, and the quality of the relationship weighs as much as technical skill. Who follows the account day to day? How many other clients does that person handle? How often are steering meetings held? The team presented during the sales phase must be the one that then works on the account: this point deserves to be confirmed in writing in the proposal.

Readable pricing and a flexible contract

Price should not be the first criterion, but it must be readable. Monthly retainer, project billing or day rates: each model can be defended, provided it is clear exactly what the budget covers, in deliverables as well as time spent. On the contract side, a very long commitment with no exit clause or interim objectives shifts all the risk onto the company. An agency confident in its work accepts review milestones.

The ability to work with other channels

SEO interacts with paid advertising, tracking, development and brand content. An agency that can coordinate with the site’s technical team, share its keyword data with paid campaigns and rely on sound measurement creates more value than an isolated provider. The question comes up in similar terms for paid search, as shown in the guide on how to choose your SEA agency.

Before signing: questions to ask and warning signs

Google itself publishes, in its Search Central documentation, a list of questions to ask an SEO provider. Here is an expanded version, as an evaluation grid that can be applied to every agency consulted.

Signals that should rule out an agency

• A guaranteed top position: Google Search Central’s documentation states that no one can guarantee a number one ranking in its results.
• A “special relationship” with Google used to sell the offer, another explicit warning from Google.
• A vague link building method, or link volumes sold as a package with no detail on the sites.
• A refusal to share changes made to the site, raw data or access.
• The same offer for every client, proposed without an audit or any question about the market.

datashake, an SEO and GEO agency built on these criteria

Among the agencies that meet all of these criteria, datashake stands out as a benchmark. Founded in 2019 by two former members of Google’s European headquarters, the group reports more than 1,000 advertisers supported, 500 million euros in media budget managed and a team of more than 100 experts. Its SEO and GEO offer, launched in 2022, follows a four-step method that answers the expertise criteria of this guide point by point: a visibility audit that identifies missing topics and content likely to be picked up by search engines and AI assistants, content structured to answer the question first, technical and E-E-A-T optimization, then continuous monitoring of the brand’s presence in Google results and in AI answers.

On proof criteria, the agency publishes averages measured across its clients: organic traffic multiplied by three, more than 45% of strategic keywords in Google’s top 3 and an average of two weeks to start appearing in LLM answers. On relationship criteria, its main strength is integration: SEO, GEO, SEA, tracking and data, CRM and an AI creative studio are brought together in the same group, which makes it possible to share keyword data between organic and paid and to rely on sound measurement. datashake is also one of the few French agencies selected for the Google Partners International Growth program, an asset for brands expanding beyond France. A free SEO and GEO visibility audit is offered by datashake.

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