OpenAI Codex is a cloud-based coding agent that runs tasks in parallel, reviews pull requests, and generates fully tested code. It goes beyond IDE autocomplete to become an async software engineering team member.
Replit Agent is an autonomous AI software engineer that can plan, build, test, and deploy full-stack applications from natural language prompts. It writes code, debugs errors, manages dependencies, and pushes to production — all within the Replit ecosystem.