https://techinpencil.com/ Animated explainers on system design and the tech you use every day. en https://techinpencil.com/favorite-food/ https://techinpencil.com/favorite-food/ Thu, 24 Sep 2026 09:00:00 GMT Beautiful Data Under the Hood 300 answers from three Claude models to the same question, drawn as pixels. Opus 5.5 picked ramen 100 times out of 100. https://techinpencil.com/rate-limiter/ https://techinpencil.com/rate-limiter/ Wed, 23 Sep 2026 09:00:00 GMT System Design Interview questions Where the simplest rate limiter leaks, and what real APIs use instead, with seven animations you can pause and play with. https://techinpencil.com/budget-3-tier/ https://techinpencil.com/budget-3-tier/ Sun, 01 Feb 2026 09:00:00 GMT System Design A budget 3-tier setup on AWS for a small SaaS, drawn as a blueprint with its monthly bill: $57.12 a month, against $155.66 done by the book. https://techinpencil.com/after-git-push/ https://techinpencil.com/after-git-push/ Tue, 14 Oct 2025 09:00:00 GMT Under the Hood Deploy an Express API to Vercel from GitHub, step by step, and see what each push creates: a deployment with its own URL, previews for branches, and rollbacks that rebuild nothing.