Lumen — production-ready Crystal social network app starter

Lumen is a free, open-source social network app built with Crystal. Lumen is a tech news link aggregator built with Kemal (Crystal) that features full social functionality: user submissions with user-defined tags, upvoting/downvoting, threaded comments, and user accounts with email/pa…. Run it locally, deploy it as a self-hosted social network app, or remix it on cenius.ai to make it your own — the whole application (code, design, seeded demo data) ships in this repository under the Apache-2.0 license.

▶ Open & edit in cenius.ai — one click to an editable workspace: describe changes in plain English, get an instant preview, one-click deploy and host. Modifications made on the platform come with full rebrand & relicense rights.

Local clone? See Quick start below. cenius.ai is the zero-setup path.

Demo

▶ Watch the full demo video — the complete walkthrough, playing on the project's cenius.ai page ·

Screenshots

Features

• User Authentication
• Link Submission with Tags
• Voting
• Tagging System
• Commenting
• User Profiles
• Light/Dark Theme Toggle
• Search
• Responsive Design
• Browse by Tag and Sort

Quick start

./install.sh   # installs dependencies + seeds demo data

See INSTALL.md for full setup and usage instructions.

Usage guide

Once Lumen is running (see INSTALL.md), open your browser at http://localhost:3000. Below is a guide to the main features and how to interact with them.

Home Page

The home page (/) displays a list of submitted links, ordered by recency (or votes, depending on the implementation). Each link shows its title, URL, tags, and submission metadata.

Example request:

curl http://localhost:3000/

Submitting a Link

Navigate to /links/submit or click the “Submit” button in the navigation bar. Fill in the form with a title, URL, and a comma-separated list of tags. After submission, you will be redirected to the newly created link’s page.

Example submission (if the form uses POST):

curl -X POST http://localhost:3000/links \
  -d "title=My Title&url=https://example.com&tags=tech,news"

(Note: exact parameter names depend on the implementation; adjust accordingly.)

Viewing a Link

Each link has a detail page at /links/:id where you can see the full information and possibly comments or actions.

curl http://localhost:3000/links/1

Browsing by Tag

Click on any tag (e.g., “tech”) to see all links associated with that tag at /tags/:tag.

curl http://localhost:3000/tags/tech

Searching

Use the search box to perform a keyword search. Results appear at /search?q=your+keywords.

curl "http://localhost:3000/search?q=crystal"

User Account

Full guide: USAGE.md

Architecture

Crystal application, delivered as a complete, runnable project (248 files). Top-level layout: bin/, lib/, public/, src/, views/. install.sh provisions dependencies and seeds demo data, so the app boots with something to show. Setup details live in INSTALL.md.

FAQ

What does it take to self-host Lumen?

Everything you need ships in this repo: clone it, run ./install.sh to install dependencies and seed demo data, then follow INSTALL.md to start it. No external services required.

What powers Lumen under the hood?

Crystal. The full source in this repository is exactly what the app runs. Highlights include light/Dark Theme Toggle.

Is Lumen free for commercial use?

Yes. The code is Apache-2.0-licensed — use it, modify it, and ship it commercially. See LICENSE.

Can I rebrand or white-label Lumen?

Yes. You can edit the source directly under the MIT license, or remix it on cenius.ai — the platform route grants full rebrand and relicense rights over your derivative.

How can I customize Lumen without editing code?

Open it on cenius.ai and describe the changes you want in plain English — the platform modifies the app and gives you a new, downloadable build.

License & rebranding

Released under the Apache License 2.0 (© 2026 Cenius AI) — free for personal and commercial use. The Cenius name/logo are trademarks (see NOTICE).

Need a customized version? Remix this app on cenius.ai — modifications made on the platform come with full rebrand & relicense rights over your derivative.

Built with cenius.ai

This entire application — code, design, seeded demo data — was generated on cenius.ai from a plain-English description.

• 🚀 Build your own app on cenius.ai
• 🎛️ Remix Lumen on the marketplace — open it in a workspace, prompt for changes, and ship your own version.

More open-source apps: the Cenius-ai catalog · showcase index