Why is Yahoo Finance returning 429 to every request, and how do you fix it?

It usually isn’t rate-limiting. Yahoo’s public endpoints now reject bare, unauthenticated requests and expect a cookie-and-crumb session: you fetch a session cookie, request a short crumb token, then send both on every call. The easy fix is the yfinance Python library, which performs that handshake automatically on first use — from any IP, including CI runners.