LTO has been operating out of Ciudad del Este since 2013 and is the most convincing thing in the border town's tourism market — which is otherwise almost entirely shopping transfers sold from the Brazilian side. They publish their SENATUR registration number and their IATA number in the footer, which nobody does unless they want you to check.
The city tour is the product to know about. Four stops, three and a half hours-ish, out of the Shopping del Este at 09:00 and 13:00 from Monday to Saturday: the San Blas cathedral in the centre, the Museo El Mensú on the yerba-mate labourers of the Alto Paraná, and across into Presidente Franco for the Saltos del Monday, whose entry is in the price. Gs 130.000 an adult, half that for a child, and they will collect you from your hotel in the city. Lunch at La Mansa Paraguay is extra.
Beyond that they run transfers — Guaraní, Foz do Iguaçu, Puerto Iguazú and Silvio Pettirossi airports, vehicles for one to thirty people — corporate movement, car hire by the day, and sport fishing on the three-border rivers. Guides work bilingually. Everything is quoted and booked over WhatsApp; there is no online checkout and no walk-in office address published.