MAP20260001982 Goffard, Pierre-Olivier Collaborative and Parametric Insurance on the Ethereum Blockchain / Pierre-Olivier Goffard and Stéphane Loisel Sumario: This article presents a blockchain-based insurance model that combines parametric coverage with collaborative risk sharing. A pool of investors, called surplus providers, commits funds to a smart contract that enables the issuance of parametric insurance policies, which automatically pay out when predefined triggers occur. Collaboration is introduced through tokenization: surplus providers receive tokens representing their share of the surplus and granting governance rights. The smart contract is implemented in Solidity on the Ethereum blockchain and deployed on the Sepolia testnet, while data processing and analysis are performed in Python. The paper also provides open-source code and highlights key research challenges to guide future developments beyond this initial proof of concept En: Astin bulletin. - Belgium : ASTIN and AFIR Sections of the International Actuarial Association = ISSN 0515-0361. - 19/01/2026 Volume 56 Issue 1 - January 2026 , p. 127 - 153 1. Blockchain . 2. Contratos inteligentes . 3. Tecnología aplicada . 4. Finanzas comunitarias . 5. Modelo estocástico . 6. Seguros paramétricos . 7. Matemática del seguro . 8. Modelos matemáticos . 9. Cálculo actuarial . I. Loisel, Stéphane . II. International Actuarial Association . III. Title.