What a good SEO agency really does
A good SEO agency does not sell you rankings. It sells you qualified traffic that turns into revenue. That nuance changes everything. A number-one ranking on a keyword with no volume or buying intent earns you nothing. A competent partner thinks in terms of revenue, not screenshots of rankings.
In practice, the work covers three pillars. Technical SEO ensures your pages are quickly crawlable, indexable and fast. Content answers the real search intent of your prospects. Link building and authority signals establish your credibility. To that is now added a fourth pillar: visibility within generative answer engines. If you want to understand the foundations before comparing providers, our article on what SEO is sets the stage.
The market has changed profoundly. More than 50% of Google queries now trigger an AI Overview, and ChatGPT has more than 900 million users per week. An agency that ignores this shift is optimizing for a shrinking world.
The selection criteria that matter
The criteria that predict a good partnership are verifiable before you sign. Focus on proof, not the sales pitch.
Proof through client results
Ask for quantified client cases, ideally in your sector or in a market of comparable difficulty. A serious agency shows growth in organic traffic, in rankings on commercial queries, and above all in business impact. Be wary of figures with no context: a 300% traffic increase can come from a near-zero starting point.
Transparency about the method
You need to understand what will be done, by whom, and why. An agency that refuses to explain its method "to protect its secret" is often hiding a lack of method. Our guide on how to improve your search ranking details the levers a good provider should know how to pull.
Who actually does the work
The salesperson who charms you is not the one who will write your content. Ask to meet the operational team and to learn what is handled in-house versus outsourced.
| Criterion | Solid agency | Risky agency |
|---|---|---|
| Commitment | Method and progress indicators | Number-one position guarantee |
| Reporting | Traffic, conversions, revenue | Isolated ranking screenshots |
| Client cases | Quantified, contextualized, sector-specific | Vague or nonexistent |
| Link building | Qualified editorial links | Cheap mass volume |
| Generative search | Explicit GEO strategy | Topic avoided or ignored |
The questions to ask before you sign
The right questions reveal an agency's level in a few minutes. Ask them in the meeting and watch how precise the answers are.
An honest answer talks about qualified traffic, conversions and revenue, never a guaranteed position.
Look for contextualized figures and a clear starting point, not an isolated percentage.
The right answer mentions editorial links and topical relevance, not a rock-bottom monthly volume.
You need to identify the operational team and the real share handled in-house.
An up-to-date agency talks about citable passages, FAQPage schema and off-site brand mentions.
A vague answer to the last question is one of the most telling signals in 2026. Generative search is no longer a marketing option: it is an execution skill. To assess an agency on this front, you can rely on our GEO Audit Templates Pack, which gives you the concrete criteria to check.
The red flags that should stop you
Certain signals justify ending the discussion immediately. They betray either incompetence or a practice that puts your site at risk.
The first is the number-one position guarantee. No one controls Google's algorithm, and a ranking guarantee is either a lie or a promise on a worthless keyword. The second is cheap mass link building: hundreds of links for a few hundred euros almost always lead to toxic profiles that expose your site to penalties.
The third red flag is opaque reporting. If you don't understand what you're paying for, you can never assess the return on investment. The fourth is the complete absence of a generative search strategy. An agency that doesn't know how to appear in an AI Overview is optimizing for the half of the market that is disappearing.
Off-site brand mentions correlate more strongly with AI citations than Domain Rating (0.266), according to Ahrefs' analysis of 200,000 domains from December 2025. An agency that only works on classic backlinks is missing the point.
One often-overlooked point: technical dependency. An agency that delivers content rendered only in JavaScript handicaps your visibility, because LLMs do not execute JavaScript. Static HTML rendering remains essential to be read by AI crawlers. A competent agency knows this and builds it in by default.
Billing models and the role of GEO
The right billing model depends on your need, not on a universal rule. Three formats dominate the French market, each with its own logic.
The monthly retainer suits ongoing support: the agency steers technical, content and link building over time. It is the most common model for a long-term strategy. The hourly or day-rate model adapts to one-off needs and advisory missions. The fixed-price project, for its part, frames a defined deliverable such as an audit or a redesign well. Whatever the model, demand a written scope and named deliverables.
The real question in 2026 is no longer the model, but the scope. An agency that bills classic SEO without integrating GEO is selling you an incomplete product. The data confirms it: only 11% of domains are cited by both ChatGPT and AI Overviews, and 92% of AI Overview citations come from the organic top 10. SEO and GEO feed each other, and a modern SEO agency treats both as a single system.
Before you sign, bring every proposal back to a simple question: do I understand what I'm paying for, and does this agency know how to make me visible where my customers actually search, on Google as well as AI? If the answer is clear, you have a partner.
Request a free GEO audit. We analyze your visibility in AI Overviews, ChatGPT and Perplexity, and you walk away with concrete actions.
Questions fréquentes
How much does an SEO agency cost in France?+
Pricing varies by model: a monthly retainer for an SMB often falls between 800 and 3,000 € per month, an hourly rate between 80 and 150 €, and a one-off project such as an audit between 1,500 and 6,000 €. The price depends on how competitive your market is and on the scope. Be wary of very low offers: they often hide automated content or low-quality backlinks.
Should you choose an SEO agency or a freelancer?+
A freelancer is enough for a simple site or a one-off need, and costs less. An agency brings several specialties (technical, content, link building, GEO) and continuity of service. Choose the agency if your market is competitive, if you have several projects running in parallel, or if you want a single point of contact who orchestrates everything.
Can an SEO agency guarantee the number-one position on Google?+
No. No serious agency guarantees a precise position, because Google does not disclose its algorithm and ranking depends on hundreds of factors beyond anyone's control. A number-one guarantee is a major red flag: run. An honest agency commits to a method and progress indicators, not to a rank.
How do you know if an agency has mastered generative search (GEO)?+
Ask how it optimizes for AI Overviews, ChatGPT and Perplexity. An up-to-date agency talks about citable passages, FAQPage schema, off-site brand mentions and static HTML rendering for AI crawlers. If it confuses GEO with classic SEO or avoids the topic, its method is behind the reality of search in 2026.
