Search Crystal Shards or follow announcements Crystal [ANN] for more.

• Awesome Crystal
  • Algorithms and Data structures
  • Blockchain
  • C Bindings
  • Caching
  • CLI Builders
  • CLI Utils
  • Code Analysis and Metrics
  • Compression
  • Configuration
  • Converters
  • Cryptography
  • Data Formats
  • Data Generators
  • Database Drivers/Clients
  • Database Tools
  • Debugging
  • Dependency Injection
  • Email
  • Environment Management
  • Examples and funny stuff
  • Framework Components
  • Game Development
  • GUI Development
  • HTML Builders
  • HTML/XML parsing
  • HTTP
  • Image Processing
  • Implementations/Compilers
  • Logging and monitoring
  • Machine Learning
  • Markdown/Text Processors
  • Misc
  • Network Protocols
  • Networking
  • ORM/ODM Extensions
  • Package Management
  • Processes and Threads
  • Project Generators
  • Queues and Messaging
  • Routing
  • Scheduling
  • Science and Data analysis
  • Search
  • Serverless Computing
  • System
  • Task management
  • Template Engine
  • Testing
  • Third-party APIs
  • Validation
  • Web Frameworks
• Community
  • Unofficial
• Resources
  • Official Documentation Translations
• Services and Apps
• Tools
  • DevOps
  • Editor Plugins
  • Shell Plugins

Algorithms and Data structures

• bisect – Inserting values into a sorted array
• blurhash.cr – BlurHash implementation
• crie – Compile-time Trie
• CrOTP – HOTP and TOTP implementation for two factor authentication
• crystal-linked-list – Implementation of Linked List
• crystaledge – A pure Vector Math library
• crystalg – A Generic Algorithm Library
• crystalline – A collection of containers and algorithms
• edits.cr – Collection of edit distance algorithms
• fzy – A Crystal port of awesome Fzy project fuzzy finder algorithm
• graphlb – Collection of graph datastructure and algorithms
• haversine – An Implementation of the Haversine formula
• kd_tree – An implementation of “K-Dimensional Tree” and “N-Nearest Neighbors”
• ksuid.cr – K-Sortable Globally Unique IDs
• markov – Build Markov Chains and run Markov Processes
• multiset.cr – Implementation of a multiset
• qr-code – QR Code generator
• radix – Radix Tree implementation
• ternary_search_tree – Ternary Search Tree

Blockchain

• Axentro – A custom blockchain platform
• Cocol – A minimal blockchain testbed
• secp256k1.cr – Elliptic curve used in the public-private-key cryptography

C bindings

• clang.cr – Libclang bindings
• crt.cr – Bindings for libncursesw and crt
• crystal-gsl – GNU Scientific Library bindings
• crystal-hunspell – Bindings for Hunspell
• curl-crystal – Bindings for libcurl
• duktape.cr – Bindings for the Duktape javascript engine
• gphoto2.cr – Bindings for the libgphoto2 library
• icu.cr – Bindings for the ICU library
• libnotify.cr – Bindings for Libnotify
• pcap.cr – Bindings for libpcap
• pledge.cr – Bindings for OpenBSD’s pledge(2)
• ssh2.cr – Bindings for libssh2 library
• syslog.cr – Bindings for syslog
• x_do.cr – Bindings for libxdo (xdotool)

Caching

• crystal-memcached – Implementation of a memcached client

CLI Builders

• admiral – A robust DSL for writing command line interfaces
• clicr – A simple declarative command line interface builder
• clim – Slim command line interface builder
• commander – Command-line interface builder
• Keimeno – A lightweight text user interface library in Crystal
• OptionParser – command-line options processing (Crystal stdlib)
• Phreak – A highly flexible Crystal CLI builder in the style of OptionParser

CLI Utils

• climate – Tiny tool to make your CLI output 🌈 coloured
• cride – A light CLI text editor/IDE
• lff – Simple and straightforward large files finder utility in command line
• oq – A performant, and portable jq wrapper to facilitate the consumption and output of formats other than JSON; using jq filters to transform the data.
• progress_bar.cr – A simple and customizable progress bar
• tablo – A flexible terminal table generator
• tallboy – Generate ASCII character tables with support for spanning cells over multiple columns

Code Analysis and Metrics

• ameba – A static code analysis tool
• linguist.cr – Using multiple ways to find programming language used in files, based on Github’s Linguist

Compression

• Crystar – Readers and writers of Tar archive format
• Gzip – readers and writers of gzip format (Crystal stdlib)
• polylines.cr — compression of series of coordinates
• snappy – Snappy compression format reader/writer for Crystal
• Zip – readers and writers of zip format (Crystal stdlib)
• Zlib – readers and writers of zlib format (Crystal stdlib)
• zstd.cr – Bindings for Zstandard compression library

Configuration

• cr-dotenv – Loads .env file
• Envy – Load environment variables from YAML
• envyable – A simple YAML to ENV config loader
• habitat – Type safe configuration for your classes and modules
• totem – Load and parse a configuration in JSON, YAML, dotenv formats

Converters

• base62.cr – Base62 encoder/decoder, well suited for url-shortening
• money – Handling money and currency conversion with ease (almost complete port of RubyMoney)
• sass.cr – Compile SASS/SCSS to CSS (libsass binding)
• wkhtmltopdf-crystal – Bindings / wrapper for libwkhtmltox (HTML to PDF / image converter)

Cryptography

• cmac – Crystal implementation of Cipher-based Message Authentication Code (CMAC)
• sodium.cr – Crystal wrapper for the libsodium crypto API

Data Formats

• BinData – Binary data parser helper with an ASN.1 parser
• config.cr – Easy to use configuration format parser
• crinder – Class based json renderer
• Crystalizer – (De)serialize any Crystal object; supporting JSON, YAML, and Byte formats out of the box
• CSV – parsing and generating for comma-separated values (Crystal stdlib)
• front_matter.cr – Separates a files front matter from its content
• geoip2.cr – GeoIP2 reader
• HAR – HAR (HTTP Archive) parser
• INI – INI file parser (Crystal stdlib)
• JSON – parsing and generating JSON documents (Crystal stdlib)
• JSON tools – An implementation of JSON Patch and Pointer RFC’s
• JSON::OnSteroids – handle and mutate JSON document easily
• maxminddb.cr – MaxMindDB reader
• toml.cr – TOML parser
• XML – parsing and generating XML documents (Crystal stdlib)
• YAML – parsing and generating YAML documents (Crystal stdlib)

Data Generators

• faker – A library for generating fake data
• hashids.cr – A library to generate YouTube-like ids from one or many numbers
• prime – A prime number generator

Database Drivers/Clients

• couchdb.cr – CouchDB client
• cryomongo – MongoDB driver
• crystal-db – Common db api
• crystal-ldap – LDAP client
• crystal-mysql – MySQL connector for Crystal
• crystal-pg – A Postgres driver
• crystal-redis – Full featured Redis client
• crystal-rethinkdb – Driver for RethinkDB / RebirthDB
• crystal-sqlite3 – SQLite3 bindings
• leveldb – Crystal bindings for LevelDB
• rocksdb.cr – RocksDB client

Database Tools

• migrate – A simpler database migration tool with transactions
• queryit – A setupless terminal based SQL query runner.

Debugging

• debug.cr – debug!(…) macro for pp-style debugging

Dependency Injection

• Athena Dependency Injection – Robust dependency injection service container framework
• Crystal-DI – Lightweight DI Container
• HardWire – A compile-time non-intrusive dependency injection system.
• syringe – A simple and basic dependency injection shard for crystal

Email

• carbon – Fun, testable, and adapter-based email library
• crystal-email – Simple e-mail sending library
• CrystalEmail – A RFC compliant Email validator
• sendgrid.cr – Simple Sendgrid Client

Environment Management

• asdf-crystal – Plugin for asdf version manager
• crenv – Crystal version manager
• rcm.cr – Redis Cluster Manager

Examples and funny stuff

• blackjack-cr – Console Blackjack
• crystal-patterns – Examples of GOF patters
• crystalworld – realworld.io back-end API implementation
• exercism-crystal – Exercism exercises
• try.cr – Try monad

Framework Components

• Athena Event Dispatcher – A Mediator and Observer pattern event library
• device_detector – Shard for detect device by user agent string
• Exception Page – An exceptional exception page for Crystal web libraries and frameworks
• graphql – Type-safe GraphQL server implementation
• graphql-crystal – GraphQL implementation
• kemal-session – Session handler for Kemal
• mochi – Authentication shard inspired by Devise supporting: Authenticable, Confirmable, Invitable & more
• motion.cr – Object oriented frontend library for Amber
• multi-auth – Standardized multi-provider OAuth2 authentication (inspired by omniauth)
• praetorian – Minimalist authorization library inspired by Pundit
• Shield – Comprehensive security for Lucky framework
• shrine.cr – File Attachment toolkit for Crystal applications. Heavily inspired by Shrine for Ruby
• tourmaline – Telegram bot framework with an API loosely based on telegraf.js

Game Development

• CrSFML – Bindings to SFML multimedia/game library
• crystal-chipmunk – Bindings to Chipmunk, a fast and lightweight 2D game physics library
• crystal-imgui-sfml – Bindings to integrate Dear ImGui into an SFML project
• entitas.cr – A Entity Component System Framework for Crystal
• glove – A library for gaming development

GUI Development

• crystal-imgui – Bindings to Dear ImGui, an immediate-mode graphical UI library
• Iu – UI framework based on the Fusion/libui.cr library, with custom elements and modified bindings from hedron-crystal/hedron

HTML Builders

• form_builder.cr – Dead simple HTML form builder for Crystal with built-in support for many popular UI libraries such as Bootstrap

HTML/XML Parsing

• docx_cr_converter – parse DOCX Word
• gumbo-crystal – Bindings for Gumbo, an HTML5 parsing library made by Google
• myhtml – Fast HTML5 Parser that includes CSS selectors

HTTP

• Cable – An ActionCable “port” to Crystal, framework agnostic, 100% compatible with the ActionCable JS Client
• cossack – Simple flexible HTTP client
• crest – Simple HTTP and REST client, inspired by the Ruby’s RestClient gem
• crul – Command line HTTP client
• digest-auth – Digest authentication
• halite – Crystal HTTP Requests with a chainable REST API, built-in sessions and loggers
• http-multiserver.cr – Mounting multiple servers via routes (a.k.a. URL mapping)
• http-params-serializable – HTTP params (de)serialization, applicable to URL queries and URL-encoded forms
• http-protection – Protection against typical web attacks
• http2 – HTTP/2 Protocol Implementation
• HTTP::Client – HTTP client (Crystal stdlib)
• HTTP::Server – HTTP server (Crystal stdlib)
• HTTP::WebSocket – HTTP WebSocket client (Crystal stdlib)
• ntlm – NTLM authentication
• proxy-fetcher.cr – Proxy lists fetching & validating library
• sse.cr – Server-Sent Events client

Image processing

• celestine – Create SVG images using a DSL
• stumpy_png – Read and write PNG images

Implementations/Compilers

• charly – Charly Programming Language
• cltk – A crystal port of the Ruby Language Toolkit
• crisp – Lisp dialect implemented with Crystal
• LinCAS-lang – A programming language for scientific computation
• mint-lang – A refreshing programming language for the front-end web
• myst-lang – A practical, dynamic language designed to be written and understood as easily and efficiently as possible
• runic-lang – In-design toy language

Logging and monitoring

• crafana – A Grafana library to help autogenerate dashboards
• Log – logging utility (Crystal stdlib)
• statsd.cr – Statsd client library

Machine Learning

• ai4cr – Artificial Intelligence (based on https://github.com/SergioFierens/ai4r)
• Cadmium – NLP library based heavily on natural
• crystal-fann – FANN (Fast Artifical Neural Network) binding
• mxnet.cr – Bindings for MXNet
• shainet – SHAInet (Neural Network in pure crystal)

Markdown/Text Processors

• markd – Yet another markdown parser built for speed, Compliant to CommonMark specification

Misc

• aasm.cr – Easy to use finite state machine for Crystal classes
• any_hash.cr – Recursive Hash with better JSON::Any included
• atomic_write.cr – Library for writing or apppending files atomically
• burocracia.cr – burocracia.cr the dependecyless shard to validate, generate and format Brazilian burocracias such as CPF, CNPJ and CEP
• callbacks – Expressive callbacks module
• circuit_breaker – Implementation of the circuit breaker pattern
• CrSignals – Signals/slots notification library
• crystal-binary_parser – Binary parser
• crystal-web-framework-stars – Web frameworks for Crystal, most starred on Github
• crz – Functional programming library
• emoji.cr – Emoji library
• gphoto2-web.cr – Web API for libgphoto2
• i18n.cr – Internationalization shard
• immutable – Implementation of thread-safe, persistent, immutable collections
• iterm2 – Display images within the terminal using the ITerm2 Inline Images Protocol
• message_verifier.cr – Verify and generate Rails ActiveSupport::MessageVerifier signed tokens
• monads – Monad implementation
• pinger – Ping IP addresses and DNS entries without requiring sudo
• port_midi – Crystal C bindings for the PortMIDI cross-platform MIDI I/O library
• retriable.cr – Simple DSL to retry failed code blocks
• simple_retry – Simple tool for retrying failed code blocks
• sslscan.cr – Crystal shard wrapping the rbsec/sslscan utility
• version_tools – Version-dependent behaviour, specified at compile-time
• wafalyzer – Web Application Firewall (WAF) Detector – shard + cli
• zaru_crystal – Filename sanitization

Network Protocols

• amqp-client.cr – AMQP 0-9.1, a messaging protocol, implemented by eg. RabbitMQ
• connect-proxy – Connect method style of HTTP tunnelling / HTTP proxy
• cr-xmpp – XMPP/Jabber Library
• Crirc – IRC protocol implementation (Client, Server, Bots)
• crystal-dns – DNS protocol implementation and resolver
• crystal-json-socket – JSON-socket client & server implementation. Inspired by and compatible with node-json-socket and ruby-json-socket
• crystal-mqtt – A MQTT client
• crystal-snmp – An SNMP implementation with version 1, 2c and 3 support
• fast_irc.cr – Fast IRC parser/generator
• jwt – Implementation of JWT (JSON Web Token)
• mDNS – DNS Service Discovery and multicast DNS
• msgpack-crystal – MessagePack library
• OAuth – OAuth consumer (Crystal stdlib)
• OAuth2 – OAuth2 client (Crystal stdlib)
• OpenSSL – bindings to libssl (Crystal stdlib)
• telnet.cr – Telnet protocol
• transfer_more – Clone of transfer.sh to uploads files

Networking

• ipaddress.cr – Library to handle IPv4 and IPv6 addresses

ORM/ODM Extensions

• avram – A database wrapper for reading, writing, and migrating Postgres databases.
• clear – ORM specialized to PostgreSQL only but with advanced features
• crecto – Database wrapper, based on Ecto
• granite – ORM for Postgres, Mysql, Sqlite
• jennifer.cr – Active Record pattern implementation with flexible query chainable builder and migration system
• onyx-sql – DB-agnostic SQL ORM with beautiful DSL and type-safe Query builder
• rethinkdb-orm – ORM for RethinkDB / RebirthDB

Package Management

• shards – Dependency manager for the Crystal

Processes and Threads

• await_async – Add keywords await & async in Crystal Lang
• neph – A modern command line job processor that can execute jobs concurrently
• promise – A Promise implementation with type inference
• werk – Dead simple task runner with concurrent support, ideal for local CI

Project Generators

• crystal_lib – Automatic binding generator for native libraries
• fez – A Kemal application generator
• libgen – Automatic bindings generator configured using JSON/YAML files

Queues and Messaging

• mosquito – Redis backed periodic and ad hoc job processing
• NATS.io – NATS client
• sidekiq.cr – Simple, efficient job processing

Routing

• orion – A minimal, rails-esque routing library
• router.cr – Minimum but powerful http router for HTTP::Server

Scheduling

• crystime – Advanced time, calendar, schedule, and remind library
• schedule.cr – Run periodic tasks
• tasker – A high precision scheduler including timezone aware cron jobs

Science and Data analysis

• alea – Repeatable sampling, CDF and other utilities to work with probability distributions
• ishi – Graph plotting package with a small API and sensible defaults powered by gnuplot
• linalg – Linear algebra library inspired by MATLAB and SciPy.linalg
• num.cr – Numerical computing library supporting N-Dimensional data
• predict.cr – Satellite prediction library using the sgp4 model
• quartz – Modeling and simulation framework

Search

• hermes – Data Mapper pattern implementation for ElastiSearch
• soegen – Elasticsearch client for Crystal similar to the stretcher gem for ruby

Serverless Computing

• crystal_openfaas – Template to enable crystal as first class citizens in OpenFaaS
• FaaStRuby – Serverless Software Development Platform for Ruby and Crystal.
• secrets-env – Extends ENV module to read values injected by docker / kubernetes secrets and other orchestration tools.

System

• baked_file_system – Virtual file system implementation
• hardware – Get CPU, Memory and Network informations of the running OS and its processes

Task management

• cake – Production-ready Make-like utility tool
• sam – Another one Rake-like task manager with namespacing and arguments system

Template Engine

• crinja – An implementation of the Jinja2 template engine
• crustache – {{Mustache}} for Crystal
• ECR (Embedded Crystal) – compile time template language which uses plain crystal expressions (Crystal stdlib)
• Jbuilder – Generate JSON objects with a Builder-style DSL, inspired by jbuilder
• Kilt – Abstraction layer for template engines
• Slang – Lightweight, terse, templating language inspired by Ruby’s Slim
• teeplate – A library for rendering multiple template files
• Water – A library for writing HTML in plain Crystal

Testing

• crotest – A tiny and simple test framework
• crytic – Mutation testing framework
• LuckyFlow – Automated browser tests similar to Capybara
• mass-spec – Web API testing library
• microtest – Small opinionated testing library focusing on power asserts
• minitest.cr – Library for unit tests and assertions
• mocks.cr – Mocking library for Crystal
• Spec – spec framework (Crystal stdlib)
• spectator – Feature rich spec framework that uses the modern expect syntax
• timecop.cr – Library for mocking with Time.now. Inspired by the timecop ruby gem
• vcr – A HTTP capture and replay implementation for crystal
• webdriver_pump – Page Object library. Inspired by Ruby’s WatirPump
• webmock.cr – Library for stubbing HTTP::Client requests

Third-party APIs

• aws-signer.cr – This library signs your HTTP requests using AWS v4
• awscr-s3 – AWS S3 interface
• awscr-signer – Sign HTTP::Request objects and generate presigned post forms
• crystal-consul – Consul API client
• crystal-darksky – Wrapper for the Dark Sky API
• crystal-swapi – Star Wars API (SWAPI) wrapper
• crystal_slack – A tool that parses Slack slash commands or send incoming web hooks
• GDAX – GDAX REST and WebSocket API Wrapper with request signing
• gitlab.cr – GitLab API wrapper
• google – Google API wrapper
• host_meta – A Web Host Metadata (https://tools.ietf.org/html/rfc6415) client
• kube-client.cr – Kubernetes API Client
• mixpanel-crystal – A library for sending events to Mixpanel
• mollie.cr – Mollie Payments API wrapper (Creditcard, PayPal, Apple Pay, Sofort, Klarna, …)
• office365 – Microsoft Graph API wrapper
• pinboard.cr – Pinboard API
• raven.cr – Raven is a client for Sentry
• stripe.cr – Stripe api wrapper
• twitter-crystal – A library to access the Twitter API
• web_finger – A WebFinger (https://tools.ietf.org/html/rfc7033) client
• ynab.cr – A library to interact with your YNAB data

Validation

• accord – Shareable validation library for Crystal Objects
• Athena Validator – Robust & flexible validation framework
• validations – Validations mixin
• validator – Data check and validation

Web Frameworks

• amber – Open source efficient and cohesive web application framework
• Athena – A web framework comprised of reusable, independent components
• grip – The microframework for writing powerful web applications
• kemal – Lightning Fast, Super Simple web framework. Inspired by Sinatra
• lucky – Catch bugs early, forget about most performance issues, and spend more time on code instead of debugging and writing tests
• runcobo – An api framework with simple, intuitive and consistent DSL, using jbuilder to render json
• Shivneri – Component based MVC web framework for crystal targeting good code structures, modularity & performance
• spider-gazelle – A Rails esque web framework with a focus on speed and extensibility

Community

• Chicago Crystal Podcast
• Chicago Crystal YouTube
• Crystal weekly newsletters
• Gitter
• Google Group
• IRC – #crystal-lang on Freenode
• Metaruby – Crystal Forum on Metaruby
• Reddit
• Stackoverflow

Unofficial

• Chinese-speaking Telegram Group – 来吧！TG 中文圈的朋友们！
• Crystal Programming Discord Server – Unofficial Discord server dedicated to the Crystal Programming Language
• Portuguese-speaking Telegram Group – Bem vindos ao Crystal Brasil!
• Russian-speaking Telegram Group – Добро пожаловать, товарищ!

Resources

• Crystal for Rubyists – Free book to bootstrap your Crystal journey
• Crystal Mastery – Screencasts for learning Crystal
• crystal-koans – Learn Crystal by writing unit tests
• crystal-lang.org – Official language site
• devdocs.io – API Documentation Browser with Crystal support
• getgood.at – Learn Crystal in a Day
• Programming Crystal – PragProg book to start your Crystal journey

Official Documentation Translations

• br.crystal-lang.org – Brazilian
• ja.crystal-lang.org – Japanese
• kr.crystal-lang.org – Korean
• ru.crystal-lang.org – Russian
• tw.crystal-lang.org – Chinese Traditional

Services and Apps

• carc.in – A web service that runs your code and displays the result
• Crank – A Procfile-based application manager (like Foreman)
• cry – Ability to execute crystal code in a fashion similar to Ruby’s pry edit
• Crystal [ANN] – Announce new project, blog post, version update or any other Crystal work
• crystalshards.herokuapp.com, crystalshards.xyz – Web services that list all available Crystal shards
• Crystular – Regular expression tester
• DeBot – IRC bot written in Crystal
• icr – Interactive console for Crystal (like IRB for Ruby)
• Invidious – Invidious is an alternative front-end to YouTube
• mpngin – A URL shortener with simple stats
• quicktype – Generate models and serializers from JSON, JSON Schema, GraphQL, and TypeScript
• shards.info – Web service that lists all repositories on GitHub that have Crystal code in them. The sources are available on GitHub

Tools

• ast_helper – Helper tool to debug parser and formatter
• crystal-base – CentOS base docker image for Crystal development
• crystal-dash-docset – Dash docset generator
• public_suffix – A small library designed to make the Public Suffix List (https://publicsuffix.org/) easier to use

DevOps

• ansible-crystal – Ansible playbook for installing crystal
• DPPM – An easy, universal way to install and manage applications as packages (mostly Linux)

Editor Plugins

• Atom
  • crystal-tools – Enables built in tools in Crystal compiler
  • language-crystal-actual – Crystal language support in Atom
• Emacs
  • emacs-crystal-mode – Crystal language support for Emacs
• scry – Code analysis server for Crystal implementing the Language Server Protocol
• Spacemacs
  • crystal-spacemacs-layer – Spacemacs contribution layer for Crystal
• Sublime
  • sublime-crystal – Crystal syntax highlighting for sublime Text
• TextMate
  • Crystal.tmbundle – Crystal syntax highlighting, compile, format command, snippets
• Vim
  • vim-crystal – Vim filetype support for Crystal
  • vim-slang – Vim filetype support for Slang Templating Engine
• Visual Studio Code
  • vscode-crystal – Crystal language support in VSCode
  • vscode-crystal-ide – Crystal IDE powered by Language Server Protocol
  • vscode-crystal-lang – Formatter, linter and syntax highlighting for cr and ecr files

Shell plugins

• crun – Crystal Run : shebang wrapper for Crystal
• crystal-zsh – .oh-my-zsh plugin