COSCUP 2025

The Ethereum Object Format (EOF) was once seen as a long-overdue reform for the Ethereum Virtual Machine — a redesign aiming to solve long-standing architectural flaws in legacy EVM. From simplifying stack operations and enhancing control flow validation, to enabling faster and safer tooling for developers, EOF promised to streamline EVM for smart contract authors, security researchers, and client implementers alike. Its benefits included better stack depth management via DUPN/SWAPN, static code validation, and performant control-flow analysis using CALLF, JUMPF, and structured code sections.

However, despite its technical merits and years of engineering effort, EOF was removed from the upcoming Fusaka upgrade. Why? This talk explores both sides of the debate: the real developer and client pain points EOF attempts to address, and the practical and political hurdles it ultimately couldn’t overcome. These include backward compatibility issues with critical tooling, incompatibility with today’s infrastructure (e.g. gas introspection and library patterns), maintenance burdens for clients, and the uncertainty introduced by future VM directions like RISC-V.

This presentation aims to provide a neutral, technical overview of EOF — what it solves, what it breaks, the concerns raised by the community, and its potential impact on the EVM’s network effect.

Will EOF be abandoned entirely, or could it return in a revised form that offers a win-win solution for all stakeholders?