<?xml version="1.0" encoding="UTF-8"?><rss version="2.0"><channel><title>System Design Simple</title><description>Tech, explained simply.</description><link>https://systemdesignsimple.com/</link><item><title>Claude Code vs Codex CLI: how we use both AI coding agents together</title><link>https://systemdesignsimple.com/claude-code-vs-codex-cli/</link><guid isPermaLink="true">https://systemdesignsimple.com/claude-code-vs-codex-cli/</guid><description>Hands-on comparison of Claude Code and Codex CLI from daily work, and why letting one review the other catches more mistakes.</description><pubDate>Sun, 01 Nov 2026 00:00:00 GMT</pubDate></item><item><title>You tap like. How does your friend&apos;s phone know a second later?</title><link>https://systemdesignsimple.com/how-a-like-reaches-your-friend/</link><guid isPermaLink="true">https://systemdesignsimple.com/how-a-like-reaches-your-friend/</guid><description>From your tap to your friend&apos;s buzz: events, a queue, a worker, live connections, Apple and Google push, and grouping 1,000 likes into one alert.</description><pubDate>Sun, 01 Nov 2026 00:00:00 GMT</pubDate></item><item><title>How do apps handle a million likes at once without crashing?</title><link>https://systemdesignsimple.com/million-likes-at-once/</link><guid isPermaLink="true">https://systemdesignsimple.com/million-likes-at-once/</guid><description>When millions tap like at once, one database row becomes a traffic jam. How big apps survive: a queue, split counters and a cache.</description><pubDate>Sun, 01 Nov 2026 00:00:00 GMT</pubDate></item><item><title>PHP security: 7 common vulnerabilities and how to fix them</title><link>https://systemdesignsimple.com/php-security-common-vulnerabilities/</link><guid isPermaLink="true">https://systemdesignsimple.com/php-security-common-vulnerabilities/</guid><description>Defensive PHP checklist: SQL injection, XSS, CSRF, password storage, uploads, sessions and unserialize, with the exact fix for each.</description><pubDate>Sun, 01 Nov 2026 00:00:00 GMT</pubDate></item></channel></rss>