I open-sourced 3 small Node utilities I pulled out of building an edtech platform

A developer building MCQplex, an exam-prep platform for Nepal's NEB curriculum, has open-sourced three small Node.js utilities extracted from that work. The packages include llm-free-cascade, which fails over across free-tier LLM APIs such as Gemini, Groq, and Cerebras with multi-key rotation and provider cooldowns; a warm-browser Puppeteer PDF renderer with a concurrency cap; and a MongoDB-backed advisory lock for node-cron jobs running across multiple instances. All three are MIT licensed, tested, and published to npm, with the developer inviting PRs, especially to update stale free-tier model names in providers.json.

I've spent the last while building MCQplex https://mcqplex.com , an exam-prep platform for Nepal's NEB curriculum. Along the way I built a few pieces of infrastructure that had nothing to do with exams specifically, so I pulled them out into their own packages: Free-tier LLM APIs Gemini, Groq, Cerebras, and others are individually rate-limited, but between them they add up to a lot of free inference if you just fail over from one to the next. This cascades a chat completion across however many you've got keys for, with automatic multi-key rotation if you've made more than one free account on a provider and cooldown for a provider that's structurally broken. Zero dependencies. js const { LLMCascade } = require 'llm-free-cascade' ; const cascade = LLMCascade.fromEnv ; const { text, provider } = await cascade.generate { system, user } ; Launching a fresh headless Chromium per PDF the naive way to use Puppeteer costs 1-2 seconds and ~200MB of RAM every time. This keeps one browser warm and gives each render its own page, with a concurrency cap so a burst of PDF requests queues instead of taking the server down. If you run node-cron jobs on more than one instance PM2 cluster, several servers , every instance fires the job unless you do something about it. This is a tiny MongoDB-backed advisory lock — steal-on-expiry, so a crashed holder can't deadlock the job forever — for whatever Mongo connection you already have. All three: zero or optional-peer dependencies, MIT licensed, tested, on npm. Feedback / PRs welcome, especially on llm-free-cascade since free-tier model names drift constantly and providers.json is set up so a one-file PR fixes a stale one.