MarkUs
submission and grading for student assignments
Active open-source Ruby on Rails apps
Hot off the push and API request, and probably some background jobs.
libraries.io
open-source discovery service
TaxonWorks
workbench for biodiversity informatics
E621.net
an art image board
Discourse
next-generation discussion platform
WikiEduDashboard
course dashboard system
va.gov
API for va.gov
GitLab
self hosted Git management
Hitobito
full-scale group hierarchy management
CircuitVerse.org
circuit simulator
Chatwoot
customer engagement platform
whitehall
government content publishing for gov.uk
OpenFoodNetwork
software to manage the lifecycle of food
Open Build Service
build service for Linux packages
Central
Fulcrum project planning tool fork
Mastodon
distributed, interconnected microblogging
OpenProject
project management system
Clain for Crown Court Defense
advocacy for defense payments
Pupilfirst
everything you need for an online school
rubytoolbox.com
catalog of all Rubygems that keeps track of popularity and health metrics
Decidim
a framework for democracy
openstreetmap.org
crowd-sourced map of the world
World Cube Association
everything for the World Cube Association
Octobox
GitHub notification manager
zammad
enterprise-ready helpdesk and customer support system
Homeland
homeland.ruby-china.org
Black Candy
self-hosted music streaming server
Notebook.ai
structured writing tool
Organization for Transformative Works Archive
archives of fanworks, including fanfic, fanart, and fan vids
Loomio
make decisions together
pinballmap.com
source code to pinballmap.com
Coursemology
open-source gameified learning platform
Convene
digital spaces
rubygems.org
The Ruby community's gem hosting service
iNaturalist.org
social network for nature stuff
Canvas LMS
enterprise-grade learning management system
Brainstormer.online
collaborative brainstorming
24pullrequests
Give back to open-source
TheOdinProject.com
free web development courses
Klaxon
get emailed when a website changes
Manage IQ
Automate, optimize, and control your cloud and virtualization services
Motor Admin
if ActiveAdmin and Blazer had a baby
RailsDevs.com
the RailsDevs.com board
exercism.io
code practice and mentorship
Autolab
course management and auto-grading of assignments
Registry
TLD management software
Punchclock
simple electronic punch clock
Growstuff
tool for small-scale food growers
Solidus
e-commerce system
OpenFarm
open database for farming and gardening knowledge
TalentProtocol.com
be your own NFT
visualizer.coffee
visualize hipster coffee machines
OnRuby
whitelabel for ruby community management
huginn
open-source IFTTT
Contributors
contributors.rubyonrails.org
Fae CMS
another CMS
Panoptes
API to support user-defined research projects
Chaskiq
full-featured live chat, support, and marketing platform
Feedbin
open-source feed reader for multiple platforms
consul
open government and participation software
kitsu
kitsu.io API server
FleetYards
A Ship Database and Web API based on the official Star Citizen Ship Matrix
Open Split Time
endurance event data management
Human Essentials
management system for essentials banks
forem
the platform that powers dev.to
CQRS Demo Application
a Rails app using advanced DDD concepts
RebelsManager
a platform for social good
DCAF Case Management
case management system
Alchemy CMS
popular content management engine
samson
Web interface for deployments
Ecosystem Dashboard
open-source ecosystem monitoring
Fat Free CRM
the original Rails-based CRM
Fat Free CRM
a clean, customizable CRM
AirCasting
platform for gathering, visualization and sharing of environmental data
Diaspora
community-run, distributed social-network
icare
carpooling platform
CrimeThinc.com
the app that powers this website
Pay
payments engine
Notebook Gallery
enterprise Jupyter notebook sharing and collaboration platform
Alaveteli
easy FOIA requests for any jurisdiction
weg.li
report bad german parkers
Blazer
dashboard for your database
AgileVentures
source code to agileventures.org
fromthepage.com
crowdsource handwritten documents
Spina
A beautiful CMS for Rails developers
Bike Index
the internet's bike registry
Spree
a flexible e-commerce platform
Violet
automation, CMS, blog, forum and email thing.
PG Hero
performance dashboard for PostgreSQL
Hound
Your code, always in style.
foreman
server lifecycle automation
vglist.co
video game library tracking
planningalerts.org.au
planning alerts for Australians
Annict.com
anime website
Open-Source Event Manager
event management tool tailored to conferences
CSVLint.io
validate CSV files
Danbooru
taggable image board
Pageflow
multimedia storytelling
Astuto
customer feedback tool
Refinery CMS
a modular and extendable CMS
ebwiki.org
database of police abuse cases against people of color
Rescue
save cute cuddly puppies
Skyderby
flight analysis and competition scoring
Camaleon CMS
yet another content management system
openSNP
annotate your SNP-set
sharetribe
Marketplace platform
Coinfi
crypto market intelligence platform
Postal
mail delivery platform for incoming and outgoing e-mail
Concerto
digital signage system
FoodSoft
manage food coop
Trailmix
A place to write.
StockAid
manages inventory for the Grateful Garment Project
Covidlist
connect vaccinations with those who need to be vaccinated
if-me.org
mental health communication
Terrastories
geostorytelling
Splits.io
speedrunning data and analysis
LumenDatabase
database of legal complaints and requests for removals
Ekylibre
farm management information system
FabManager
FabLab management tool
Tracks
software for implementing David Allen's Getting Things Done™ methodology
Envizon
network visualization and pentest reporting
lobsters
link-aggregation site, inspired by Hacker News
Haven
self-hostable private blogging
Texterify.com
translation and localization management
Podify
make podcasts from youtube-dl
Upcase.com
learning platform for programming
Caffeinate
a framework for easily creating and scheduling email campaigns
Dog API
an API for doggo info
Errbit
open source, self-hosted error catcher
Expertiza
peer-reviews app, supported by the National Science Foundation
Ciao
uptime monitoring
Coyote
image annotation
Verboice
Toolkit for people who literally "need a voice"
HRMS
HR management
OpenSourceRails.org
the codebase to this site
TimeOverflow
time banking system
ActiveWorkflow.org
turn complex requirements to workflows
Gamocosm.com
Minecraft server hosting
getsiteinspector.com
a tool for developers to check their pages
sumofus.org
source code to sumofus.org
dokno
Rails Engine for storing and managing an app's domain knowledge
Hackershare
social bookmarking and knowledge-sharing
tip4commit.com
reward contributors
alonetone
home for musicians, their tracks and albums
Racing On Rails
bike racing association management
Listed.to
online publications with automatic newsletters
Outpost
service directories platform
Storytime
another CMS
Locomotive CMS
a multisite CMS with liquid templating
Diveboard
Diveboard.com
Open Source Billing
Beautifully Simple Billing Software
Peatio
crypto currency exchange software
Calls For Proposal App
manage a conference CFP
TheyVoteForYou
Holding politicians accountable
PublicLab.org
collaborative knowledge-exchange platform
Carto
location intelligence and data visualization
CodeTriage
directory of open-source projects with open issues
nindika.com
nintendo switch e-shop
Calagator
community calendar platform
Droptune
music notifications for Spotify and Apple Music
Morph.io
web scraping tool
LearnAwesome.org
social network of learners
Wreeto
note-taking, knowledge management, and wiki
Abalone
data tracking and analytics for conservation efforts
Huboard.com
better GitHub issues
RubyTogether.org
RubyTogether.org
Fulcrum
Original project planning
Fairmondo
free market place in the hand of the users
Cuttlefish
a good-enough SMTP server so you can ditch SMTP providers
Action Center
EFF Action Center platform
Airesis
eDemocracy
Redmine
web based project management
HellRaiser
vulnerability scanner
Drug Gene Interaction Database
The Genome Institute's drug gene interaction database
Plylst
Spotify playlist tool
Datoji
easy JSON mocking for developers
FeedBunch
simple and elegant reader
Helpy
A Modern Helpdesk Alternative
Hackathon Manager
hackathon registration and logistics
Staytus
status pages
GitReports.com
allow anonymous users to submit bugs to GitHub repos
Orientation.io
Wage war against outdated documentation
Ghostlight Folio
theatrical production management
CodeCuriosity.org
platform to reward OSS contributors
Workarea
enterprise-grade commerce platform
Bluedoc
document management tool
ShinyCMS
plugin-based CMS
Barong
auth server
Pokr
agile estimating and planning
Simple Discussion
simple and extensible Rails forum
Vinifera
tool to monitor leaked secrets
CaseIn
CMS toolkit
HyperCable
analytics
Radiant CMS
No-frills CMS
brief-ideas
journal for brief ideas
EasyRaceLapTimer
open-source IR lap time tracker
datorss.com
RSS search
OneBody
church management software
Pig CI
Rails performance monitoring, plus CI
nokul
solution for universities to manage all the complex procedures of a university online
Amahi
your personal cloud and media server
FederalRegister.gov
daily journal for the United States Government
Juvia
commenting server of the likes of Discus or IntenseDebate
Catarse
open-source crowdfunding platform
AppPerf
application and performance monitoring tool
Gwaphics
graphic design tool
LocalOrbit
local food management stuff
Reservations
equipment loans and reservations software
Sanataro
household accounting software
Coderwall
Professional network for software engineers
Hours
Time registration that doesn't suck.
Recipy.fr
defunct website of a recipe site
Comfortable Mexican Sofa
a lovely-named CMS
Lale Help
collaborative platform for refugee support
Email Dashboard
email suite for marketing and CRM
Classroom
automates repository creation and access control for teachers
TagTeam
social tagging for academics
BareMetrics.com
v1 of baremtrics.com
Duckrails
tool to mock API endpoints
Binda CMS
headless CMS
Mission of Mercy
management of free dental clinics
Snippet Manager
manage your snippets
Intercity
web-based Dokku deployment
SmartVPN Billing
billing management for hosting
Brimir
an email helpdesk
Twist
book review application
C2
approval process automation
Xrono
asset and time-tracking
JobsWorth
Project management, time tracking, billing
Trado
simple e-commerce platform for developers
Heaven
github flow orchestrator
adopt-a-hydrant
adopt-a-hydrant software
Case File Editor
editor for digital case files
Lewsnetter
email marketing application
AskThem
monitor and interact with local government
Squash
exception reporting and bug analysis by Square
GitLab CI
continuous integration server
uk-postcodes
postcodes application
Helpful
simple and elegant support system
Do Continuous Integration Yourself
open-source CI server
Teambox
the original teambox.com
RailsCasts
RailsCasts.com source code (thanks Ryan)