security-audit is an open-source coding agent skill from Cloudflare’s security team (MIT, about 34K stars) and the starting point of its internal vulnerability-hunting system. Install it in Claude Code or Codex, say “security audit this codebase”, and it runs reconnaissance, hunting, adversarial validation, structured output, independent review and reporting. We tested the install and bundled tests and explain the two modes, three tiers, sandboxing and cost.

Claudemy is a free, open-source Claude Code skill: give it a topic and it reads 20 to 40 web pages, compares what they say, and builds about 12 two-minute, two-host audio lessons, each with a card and a small exercise, while a citation check blocks fabricated links. This post covers installation, voice options, other languages and cost.

llmspeed is a free, open-source web tool: pick a GPU or Mac, a model and a quantization, and it types out a response at the estimated speed, tells you whether the model fits, and lets two setups race. How to use it, how to read its measured/derived/projected labels, and speed and time-to-first-token tables from the RTX 3060 to the 5090, Macs and the Ryzen AI Max+ 395.