localhost:4000

Port 4000 is the default port for Jekyll (Ruby static site generator) and Phoenix Framework (Elixir). If you're building a Jekyll blog, GitHub Pages site, or Phoenix web application, this is your development URL.

What Uses Port 4000?

Jekyll Development

Jekyll powers GitHub Pages and is one of the most popular static site generators.

# Install Jekyll
gem install jekyll bundler

# Create new site
jekyll new my-blog
cd my-blog

# Start development server
bundle exec jekyll serve

# With live reload
bundle exec jekyll serve --livereload

# Access at http://localhost:4000

Jekyll Configuration

# _config.yml - change port
port: 4000
host: localhost
livereload: true

# Or via command line
jekyll serve --port 4001

Phoenix Framework

Phoenix is an Elixir web framework known for real-time features and performance.

# Create new Phoenix app
mix phx.new my_app
cd my_app

# Setup database
mix ecto.create

# Start server
mix phx.server

# Access at http://localhost:4000

Phoenix Configuration

# config/dev.exs
config :my_app, MyAppWeb.Endpoint,
  http: [port: 4000],
  debug_errors: true,
  code_reloader: true

Change Default Port

# Jekyll
jekyll serve --port 4001

# Phoenix (environment variable)
PORT=4001 mix phx.server

# Gatsby
gatsby serve --port 4001

Troubleshooting