Kaelum

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Why Kaelum? ​

Name & inspiration ​

Kaelum is inspired by the Latin word caelum (sky, heaven). The name evokes two closely related ideas:

  • Clarity and elevation — reduce noise and let developers focus on the important parts of an application, elevating the learning and prototyping experience.
  • A small, steady platform — a lightweight foundation you can build on, similar to how a clear sky is a simple but essential backdrop.

Kaelum was designed to be a compact layer above Express: small, pragmatic and easy to adopt, while remaining flexible for advanced uses.

Problems Kaelum aims to solve ​

Developers — especially beginners and students — commonly face recurring friction when starting Node.js web projects:

  • Heavy initial setup: configuring parsers, static serving, security middleware, route scaffolding and project structure takes time and distracts from application logic.
  • Boilerplate duplication: many small projects repeat the same wiring (body parsers, static folders, logging).
  • Steep cognitive load for beginners: newcomers must learn many independent tools (Express middleware, project layout, npm scripts) before writing a single route.
  • Inconsistent starter templates: different tutorials recommend different layouts, which confuses learners.

Kaelum reduces this friction by providing an opinionated minimal starter surface while keeping escape hatches to raw Express for advanced control.

Relationship with Express and other frameworks ​

Kaelum & Express ​

Kaelum builds on top of Express rather than replacing it. Key aspects of this relationship:

  • Kaelum encapsulates common Express setup (parsers, static serving, CORS, Helmet, logging) into a compact API (createApp(), start(), addRoute(), setConfig()).
  • The underlying Express app is still available — you can call app.use(), app.listen() or any Express API when needed.
  • This approach gives the best of both worlds: simplicity for quick starts and full flexibility for production-grade adjustments.

Comparison with other projects ​

  • Express — Very minimal; Kaelum uses Express as runtime and exposes simpler helpers and a CLI scaffold.
  • Fastify — Focused on performance and schema-based validation; Kaelum’s goal is developer ergonomics and education rather than micro-benchmarks.
  • NestJS — Highly opinionated, modular architecture with TypeScript-first design; Kaelum intentionally remains lightweight and unopinionated about controllers/DI to keep the barrier low.
  • Create React App / Vite scaffolding — Kaelum’s CLI (npx kaelum create) is inspired by the idea of quick scaffolding — generate a working project with sensible defaults and an easy path to customization.

Different “Whys” — reasons to choose Kaelum ​

1. For learning and teaching ​

  • Short, predictable API helps instructors demonstrate web fundamentals without the distraction of tooling.
  • Pre-configured templates and examples let students run code immediately and focus on HTTP concepts.

2. For rapid prototyping ​

  • Start a working web or API project in seconds (npx kaelum create my-app), then iterate.
  • Useful for demos, hacks, and proof-of-concept microservices where speed matters.

3. For small production services ​

  • The lightweight surface is suitable for internal tools and microservices where a compact, readable codebase matters.
  • When more control is required, the developer steps down to Express without rewriting the app.

4. For extensibility and ecosystem ​

  • Kaelum is intentionally composable: you can create opinionated layers (authentication stacks, admin kits) on top of Kaelum.
  • Its permissive license and small API make it easy to adopt as a dependency for higher-level tooling.

Design decisions that support the “why” ​

  • Sensible defaults: JSON parsing and a public/ static folder are enabled by default so apps work immediately.
  • Single point of configuration: setConfig() gives a single place to toggle CORS, Helmet, logs, static folder and more.
  • Small API surface: a handful of helpers (createApp, start, addRoute, apiRoute, setMiddleware, setConfig) keeps learning friction low.
  • CLI-driven scaffolding: npx kaelum create produces a ready-to-run structure using MVC conventions to teach best practices.
  • No strong opinions beyond defaults: Kaelum avoids bundling ORM, template engine or deployment choices — leaving these to the developer.

Example: Why the API is compact ​

Express (typical minimal app)

js
// express-app.js
const express = require('express');
const cors = require('cors');
const helmet = require('helmet');

const app = express();
app.use(express.json());
app.use(cors());
app.use(helmet());
app.use(express.static('public'));

app.get('/', (req, res) => res.send('Hello Express!'));
app.listen(3000, () => console.log('Listening on 3000'));

Kaelum (equivalent in fewer lines)

js
// app.js (Kaelum)
const kaelum = require('kaelum');
const app = kaelum();

app.setConfig({ cors: true, helmet: true }); // safe defaults in one call
app.addRoute('/', { get: (req, res) => res.send('Hello Kaelum!') });
app.start(3000);

The Kaelum example demonstrates the central idea: reduce wiring and let developers declare intent.

When not to choose Kaelum ​

Kaelum intentionally targets small to medium projects, education and prototyping. Consider other solutions if you need:

  • Heavy architectural patterns out-of-the-box (e.g., NestJS with DI and modules).
  • Maximum HTTP throughput and schema-driven JSON serialization as a primary concern (Fastify may be preferable).
  • A full-stack opinionated platform with SSR and routing built-in (Next.js, Nuxt).

Migration & interoperability ​

Because Kaelum relies on Express under the hood:

  • You can migrate an Express app to Kaelum incrementally by replacing setup code with Kaelum helpers.
  • Existing Express middleware still works with Kaelum apps.
  • Kaelum projects can adopt third-party Express tools (templating engines, ORMs, validators) without friction.

Concluding notes ​

Kaelum’s mission is pragmatic: provide a small, well-documented foundation that helps learners and engineers get productive fast — without hiding the underlying platform. It is best understood as a starter scaffold + ergonomic helpers for Express, optimized for education, prototypes and small services, and intentionally designed to be extended.

See also ​

Released under the MIT License.

Copyright © 2025 Kaelum