Who is Eric St-Cyr Founder of Prostar SEO ?

A first career in international finance, and the collapse that ended it

Éric St-Cyr spent his first career in international finance. He began at a Canadian bank, then moved to the Cayman Islands, where he founded and directed his own wealth-management firm. That chapter ended in a very public collapse in 2014, when a U.S. government sting operation brought his companies down. It cost him nearly everything he had built.

One fact matters more than any headline: no client of his was ever a victim. Nobody’s savings were stolen, mismanaged, or lost. What his firm did was help clients keep their money away from the tax authorities. It is nothing to be proud of, and he does not pretend otherwise, but it was a tax story, not a theft story. How the sting itself created the charge that made the headlines is a story he tells in full, without flattering himself, in the memoir.

He wrote about it himself. In 2016, Éditions Parfum d’encre published his memoir À l’ombre du soleil : paradis fiscaux, démesure et déchéance, a 384-page account of high finance, offshore banking, excess, and the fall that followed. The book became a bestseller in Canada and is catalogued by Bibliothèque et Archives nationales du Québec under ISBN 978-2-924251-32-4. Éric kept the rights and would rather it be read than sold: download the English edition, In the Shadow of the Sun, free (ePub), or email us for the French original.

That experience shapes how ProStar SEO operates. Éric has seen an industry reward confident storytelling over verified numbers, and he has paid for it. He now runs an agency built on the opposite instinct.

How a rebuild in his fifties turned into an SEO agency

The rebuild began with a favor rather than a business plan. His daughter had launched a food-tech startup called MiumMium, she needed organic traffic she could not afford to buy, and he taught himself search engine optimization to help her get it. That project exposed a gap: business owners were paying agencies for rankings without ever being shown the reasoning, the benchmark, or the measurement behind the invoice. Éric St-Cyr founded ProStar SEO in 2019 to close that gap and incorporated the company in Québec in 2020. The agency expanded across Canada in 2021, added PPC, content strategy, UX optimization, and web development in 2022, and opened international projects in the United States, France, and Spain in 2023. ProStar SEO has since worked with more than 600 businesses.

Expertise forged in the industries Google Ads will not touch

Éric St-Cyr developed his method in the hardest search markets in North America: cannabis and CBD, online gambling and casinos, cosmetic and plastic surgery, dating platforms, dentistry, healthcare, contracting, and legal services. These verticals share one brutal characteristic. Google Ads restricts or bans them outright, which makes organic ranking the entire growth channel. Techniques that survive a cannabis SERP are more than sufficient for a dental clinic or a law firm.

That expertise now runs through a family of specialized agencies Éric founded alongside ProStar SEO: Agence SEO Paris for the French market, CannabisSEO.ai, LegalSEO.agency, CasinoSEO.ai, RealEstateSEO.ai, PlasticSurgerySEO.agency, MedSEO.agency, and DentistSEO.agency. Each brand concentrates the vocabulary, entity set, compliance constraints, and ranking patterns of a single industry into one tightly held topical territory, rather than diluting topical authority across every market at once.

Contextual Density: the measurement framework behind every page we build

Éric St-Cyr established Contextual Density as a working SEO discipline. The underlying signal was surfaced by Lee Witcher in 2022. Éric turned the observation into something measurable: a quantification framework, a measurement protocol, and an optimization methodology, tested across more than a hundred client implementations and published as Understanding Contextual Density: The Algorithmic Factor Reshaping Modern SEO in March 2025. Roughly eight out of ten pages optimized to the framework improved their rankings.

Contextual Density (CD) = ( Σ(KV) + Σ(RE) + Σ(LSI) ) / ( TW − SW ) × 100

Σ(KV) counts keyword variations, Σ(RE) counts recognized entities, Σ(LSI) counts latent semantic terms, and the denominator is total words minus stop words. The score measures insight per word: diversity beats frequency, and placement compounds it. In practice we measure the pages already ranking on page one, extract their variation counts, entity sets, and semantic breadth, and build to a documented benchmark rather than to an opinion. These are correlations, not proven causation, and Contextual Density is one factor among many, but optimizing for it works either way.

What Éric St-Cyr learned actually counts

“The only thing that truly counts in SEO is getting you more clients. Ranking for irrelevant keywords, or pulling in traffic that never converts, is money lost for the client. I have watched it happen, and I am not interested in selling it.”

It is easy to win rankings that flatter a report and do nothing for a business. We choose keywords on commercial intent first, and we judge the work by the leads, calls, bookings, and sales it produces. If the traffic grows and your client count does not, we treat that as a problem to solve rather than a win to celebrate.

Recognition and standing in the industry

Éric St-Cyr’s standing rests on work that can be checked rather than on titles he assigned himself: nine founded agencies, a bestselling memoir catalogued by Bibliothèque et Archives nationales du Québec, a published measurement framework, and more than a decade of practice across cannabis, legal, casino, medical, dental, real estate, and cosmetic surgery search markets, including one client now earning over ten million organic clicks a month.

He is also a recurring guest on Ca$hMire de Pierre Couture, the Québec personal finance and economics podcast, where he has appeared across numerous episodes devoted to search, including two three-part series and standalone episodes on using AI in SEO, analyzing a website’s SEO, and testing parasite SEO. When a financial journalist needs search explained to a business audience, this is who he calls back.

We would rather list those facts than call ourselves the best. Any agency can claim a superlative; very few can hand you an ISBN, a formula, a publication date, and nine live domains and invite you to verify all of them.