In Brazil, Gemini says check the realtor's CRECI. ChatGPT never does

Short answer: ask ChatGPT and Gemini, in Portuguese, for the best real estate agencies in a Brazilian city, and Gemini tells you to check the agency's CRECI registration in 21 of its 26 answers - "Sempre peça o número do CRECI do corretor e da imobiliária." ChatGPT does it in none of its 26. Across 19 trades, Gemini points the customer to a public register - the CRECI for estate agents, the CRO for dentists, the OAB for lawyers, the DETRAN for driving schools, the SUSEP for insurance brokers, the CNPJ for any company - in 193 of its 414 answers, and gives the web address of the official site in 109. ChatGPT does it in 76, and gives no address.

Gemini hands the customer the register. ChatGPT hands them a reminder, sometimes.

What was measured

The Brazilian study (collected August 6, 2026) asked ChatGPT (gpt-4o-mini), Gemini and Perplexity the same buyer questions in Portuguese ("Quais são os melhores dentistas no Recife? Me dá uma lista com as suas recomendações.") for 19 trades in 13 cities, through their APIs, without any location: 414 answers per engine. ChatGPT and Gemini answer here without web search; Perplexity searches the web by design. Brazil has public registers a customer can query in a minute: the CNPJ for companies, and the professional councils. We extracted every sentence naming one - CNPJ, CRO, OAB, CRECI, CRC, CREA, SUSEP, DETRAN and others - with a pattern tested on 10 sentences first: 588 sentences, all read by hand. Each was classed: advice built on a register ("check", "ask for the number", "prefer a registered company"); a claim that named businesses are registered; a registration that Perplexity read online; other information (the OAB code of ethics, DETRAN fees); or a false friend - "CRM" and "CRO" in marketing, "CFC" in a driving school's name. We then tested the 64 official addresses Gemini gave, on October 22, 2026. On October 6 we measured how rarely AI names a proof a customer can check: AI says green 135 times and names one certification.

Lawyers are the only trade where the two agree

Both engines tell the customer to check the OAB in all 26 answers about lawyers. Everywhere else, Gemini goes further: driving schools (25 of 26, the DETRAN, against 0), insurance brokers (25, the SUSEP, against 11), dentists (23, the CRO, against 10: "Confira se o dentista é registrado no Conselho Regional de Odontologia (CRO) e se possui especializações relevantes." is ChatGPT at its most specific). For a driving school in Brasília, Gemini writes: enter the DETRAN's site and "verifique se a autoescola está com a licença ativa". Neither mentions a register for restaurants, bakeries, hairdressers, beauty salons, hotels, garages, marketing agencies, recruiters or wedding photographers. Of the 64 official addresses Gemini gave from memory, 47 answered, 5 refused our robot, 1 returned an error and 8 exist but did not answer from Europe; 3 point to domains that do not exist, in 4 answers - creci-df.gov.br, where the council's real address, crecidf.gov.br, appears in another of its answers. In 5 answers Gemini says the businesses it lists are registered: "Todas as listadas possuem CNPJ consolidado e registro na SUSEP", of insurance brokers in Belo Horizonte. Without web search it cannot have checked. Perplexity, which reads the web, does what the other two cannot: in 21 answers it reports the registration it found on a named business's pages - "aparece com CRECI 10017-J e endereço completo em Boa Vista", of an agency in Recife - and in 6 it quotes the number.

What it means if you are the business

If you hold a registration - CRECI, CRO, OAB, SUSEP, DETRAN accreditation, or simply a CNPJ - write it on your site in full, as text, next to your name and address. Gemini tells your next customer to look it up, often with the council's address, and Perplexity, which reads pages, repeats a registration when it finds one. A number your customer can check in thirty seconds on the council's site is the cheapest proof you can offer. That is a reasonable step, not a lever with a known effect: we did not measure whether a published registration makes a business more likely to be named.

What this does not prove

• These are the models' answers through their APIs, without the user's location; ChatGPT and Gemini answered without web search, Perplexity searched by design.
• Each question was asked once, on August 6, 2026; another day could give other answers.
• We tested Gemini's addresses from Europe on October 22, 2026: the 8 that did not answer may work from Brazil.
• We did not check whether the businesses Gemini says are registered are registered, nor the numbers Perplexity quotes.