Mackarel allows you to write acceptance tests in Rails in a readable way without having to deal with things like Cucumber.

Zero-configuration command-line HTTP server.

A library that makes it easy to add an HTML based GUI to your ruby library

A suite of tools for inspecting, interfacing and working with MagLev. It consists of a number of Rack middlewares to record runtime information in the stone, an associated set of Sinatra middlewares for exposing said information through a JSON interface, and a number of Sinatra web-applications that take advantage of that interface to build a few simple browser-based development tools.

MailCatcher NG brings the beloved MailCatcher into the modern era: fast, reliable SMTP catching with a stunning real-time interface, updated dependencies, and powerful email inspection features

Rails system mail management solution.

Basic Mailjet ActionMailer support

A web interface to view emails sent out when developing in Rails

Funnels email into HipChat using CloudMailIn

Mainline is a rails plugin which exposes your rails app via webrick to allow testing with browser automators such as Selenium or Watir. Mainline allows your rails actions to run in the same transaction as your unit tests so you can use fixtures, factories, or whatever.

simple web application framework for learning.

Framework built from scratch

Minuscule algebraic types for Ruby

Mandrake loads middlewares conditionally, and it provides two options and DSL for setting conditions

Verify signed HTTP requests from Manifold

A Ruby gem providing development tools for MapLibre GL JS styles, including advanced layer filtering, terrain visualization, elevation profiles, and performance monitoring.

Runs a local server so you can edit and local (auto) save markdown documents.

# Markdown Explorer This Ruby Gem uses Sinatra and Redcarpet to allow you to CRUD markdown files on your local system.

A minimal Rack app for drafting and previewing Markdown

{Marlowe}[https://github.com/KineticCafe/marlowe] is a Rack middleware that extracts or creates a request ID using a pre-defined header, permitting request correlation across multiple services. When using Rails, Marlowe automatically adds itself to the middleware before <tt>Rails::Rack::Logger</tt>. As of Marlowe 3.0, a Faraday middleware is provided (<tt>require 'marlowe/faraday'</tt>).