Awesome Crystal Overview

:gem: A collection of awesome Crystal libraries, tools, frameworks and software

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Awesome Crystal

A curated list of awesome Crystal code and resources. Inspired by awesome (⭐312k) and awesome-awesomeness (⭐31k). The goal is to have projects mostly stable and useful for the community.

Search shards at shards.info or follow announcements Crystal [ANN] for more.

Contributions are welcome. Please take a quick look at the contribution guidelines (⭐3.3k) first.

Awesome Crystal
Community
- Unofficial
Resources
- Official Documentation Translations
Services and Apps
Tools

Algorithms and Data structures

bisect (⭐12) - Inserting values into a sorted array
blurhash.cr (⭐23) - BlurHash (⭐15k) implementation
crie (⭐12) - Compile-time Trie
CrOTP (⭐63) - HOTP and TOTP implementation for two factor authentication
crystal-linked-list (⭐13) - Implementation of Linked List
crystaledge (⭐26) - A pure Vector Math library
crystalg (⭐38) - A Generic Algorithm Library
crystalline (⭐129) - A collection of containers and algorithms
csuuid (⭐15) - A Chronologically Sortable UUID
edits.cr (⭐16) - Collection of edit distance algorithms
fzy (⭐45) - A Crystal port of awesome Fzy project fuzzy finder algorithm
Goban (⭐25) - A fast and efficient QR Code implementation
graphlb (⭐19) - Collection of graph datastructure and algorithms
haversine (⭐16) - An Implementation of the Haversine formula
HKDF (⭐1) - HMAC-based Extract-and-Expand Key Derivation Function rfc5869
kd_tree (⭐16) - An implementation of "K-Dimensional Tree" and "N-Nearest Neighbors"
ksuid.cr (⭐15) - K-Sortable Globally Unique IDs
markov (⭐21) - Build Markov Chains and run Markov Processes
multiset.cr (⭐4) - Implementation of a multiset
named_information (⭐0) - Naming Things with Hashes rfc6920
qr-code (⭐17) - QR Code generator
radix (⭐102) - Radix Tree implementation
s2_cells (⭐0) - S2 Geometry for spatial indexing
secure-remote-password (⭐7) - SRP-6a protocol for authentication over an insecure network
SPAKE2+ (⭐1) - Password Authenticated Key Exchange (PAKE) protocol, comparable to SRP-6a
splay_tree_map (⭐14) - Splay Tree implementation that conforms to the Hash ducktype
verhoeff (⭐0) - Implementation of the Verhoeff checksum algorithm

Blockchain

Axentro (⭐193) - A custom blockchain platform
Cocol (⭐19) - A minimal blockchain testbed
secp256k1.cr (⭐48) - Elliptic curve used in the public-private-key cryptography

C bindings

augeas.cr (⭐7) - Bindings for Augeas
clang.cr (⭐47) - Libclang bindings
crt.cr (⭐27) - Bindings for libncursesw and crt
crystal-gsl (⭐3) - Bindings for GNU Scientific Library
crystal-hunspell (⭐6) - Bindings for Hunspell
duktape.cr (⭐136) - Bindings for the Duktape (⭐5.9k) javascript engine
fftw.cr (⭐12) - Bindings for FFTW library
gphoto2.cr (⭐16) - Bindings for the libgphoto2 library
gpio.cr (⭐1) - Bindings for the gpiod library (general purpose IO control and feedback)
icu.cr (⭐11) - Bindings for the ICU library
libnotify.cr (⭐26) - Bindings for Libnotify
nlopt.cr (⭐3) - Bindings for NLOpt
pcap.cr (⭐25) - Bindings for libpcap
pledge.cr (⭐8) - Bindings for OpenBSD's pledge(2)
ssh2.cr (⭐43) - Bindings for libssh2 library
syslog.cr (⭐10) - Bindings for syslog
v4l2.cr (⭐5) - Bindings for Video4Linux2
wasmer-crystal (⭐89) - Bindings for the wasmer WebAssembly runtime
win32cr (⭐14) - Bindings for Win32 API
x_do.cr (⭐18) - Bindings for libxdo (xdotool)

Caching

crystal-memcached (⭐35) - Implementation of a memcached client

CLI Builders

admiral (⭐135) - A robust DSL for writing command line interfaces
Athena Console (⭐16) - Allows for the creation of CLI based commands
clicr (⭐29) - A simple declarative command line interface builder
clim (⭐121) - Slim command line interface builder
Cling (⭐23) - A modular, non-macro-based command line interface library
commander (⭐126) - Command-line interface builder
Keimeno (⭐14) - A lightweight text user interface library in Crystal
OptionParser - command-line options processing (Crystal stdlib)
Phreak (⭐32) - A highly flexible Crystal CLI builder in the style of OptionParser

CLI Utils

climate (⭐14) - Tiny tool to make your CLI output 🌈 coloured
coin (⭐6) - Command-line application that performs currency conversion via the Fixer API
cride (⭐50) - A light CLI text editor/IDE
git-repository (⭐2) - A git cli wrapper querying and cloning remote repositories with minimal data transfer
hetzner-k3s (⭐1.6k) - A CLI tool to quickly create and manage Kubernetes clusters in Hetzner Cloud
lff (⭐17) - Simple and straightforward large files finder utility in command line
meet (⭐38) - Start a jitsi meeting quickly from the comfort of your command line
oq (⭐190) - A performant, and portable jq wrapper to facilitate the consumption and output of formats other than JSON; using jq (⭐30k) filters to transform the data
progress_bar.cr (⭐15) - A simple and customizable progress bar
tablo (⭐28) - A flexible terminal table generator
tallboy (⭐56) - Generate ASCII character tables with support for spanning cells over multiple columns

Code Analysis and Metrics

ameba (⭐510) - A static code analysis tool
linguist.cr (⭐8) - Using multiple ways to find programming language used in files, based on Github's Linguist

Compression

Crystar (⭐38) - Readers and writers of Tar archive format
Gzip - readers and writers of gzip format (Crystal stdlib)
polylines.cr (⭐10) — compression of series of coordinates
snappy (⭐18) - 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 (⭐41) - Bindings for Zstandard (⭐23k) compression library

Configuration

cr-dotenv (⭐94) - Loads .env file
Envy (⭐7) - Load environment variables from YAML
envyable (⭐6) - A simple YAML to ENV config loader
habitat (⭐83) - Type safe configuration for your classes and modules
totem (⭐66) - Load and parse a configuration in JSON, YAML, dotenv formats

Converters

base62.cr (⭐10) - Base62 encoder/decoder, well suited for url-shortening
crunits (⭐6) - Tool for converting units of measure (miles to kilometers, celsius to fahrenheit etc)
money (⭐31) - Handling money and currency conversion with ease (almost complete port of RubyMoney (⭐2.7k))
sass.cr (⭐35) - Compile SASS/SCSS to CSS (libsass (⭐4.3k) binding)

Cryptography

cmac (⭐5) - Crystal implementation of Cipher-based Message Authentication Code (CMAC)
ed25519 (⭐7) - the Ed25519 elliptic curve public-key signature system described in [RFC 8032]
monocypher.cr (⭐17) - Crystal wrapper for the Monocypher crypto library
sodium.cr (⭐49) - Crystal wrapper for the libsodium crypto API

Data Formats

BinData (⭐48) - Binary data parser helper with an ASN.1 parser
config.cr (⭐14) - Easy to use configuration format parser
crinder (⭐28) - Class based json renderer
Crystalizer (⭐39) - (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 (⭐11) - Separates a files front matter from its content
geoip2.cr (⭐17) - GeoIP2 reader
HAR (⭐22) - HAR (HTTP Archive) parser
INI - INI file parser (Crystal stdlib)
JSON - parsing and generating JSON documents (Crystal stdlib)
json-schema (⭐12) - convert JSON serializable classes into a JSON Schema representation
JSON::OnSteroids (⭐24) - handle and mutate JSON document easily
maxminddb.cr (⭐23) - MaxMindDB reader
toml.cr (⭐58) - TOML parser
XML - parsing and generating XML documents (Crystal stdlib)
YAML - parsing and generating YAML documents (Crystal stdlib)

Data Generators

faker (⭐147) - A library for generating fake data
hashids.cr (⭐52) - A library to generate YouTube-like ids from one or many numbers
prime (⭐1) - A prime number generator

Database Drivers/Clients

couchdb.cr (⭐13) - CouchDB client
cryomongo (⭐71) - MongoDB driver
crystal-db (⭐299) - Common db api
crystal-ldap (⭐17) - LDAP client
crystal-mysql (⭐108) - MySQL connector for Crystal
crystal-pg (⭐462) - A Postgres driver
crystal-redis (⭐380) - Full featured Redis client
crystal-rethinkdb (⭐22) - Driver for RethinkDB / RebirthDB
crystal-sqlite3 (⭐136) - SQLite3 bindings
leveldb (⭐39) - Crystal bindings for LevelDB
rocksdb.cr (⭐38) - RocksDB client
surrealdb.cr (⭐5) - Unoffical SurrealDB HTTP & Websocket Client

Database Tools

migrate (⭐31) - A simpler database migration tool with transactions

Debugging

backtracer.cr (⭐15) - Shard aiming to assist with parsing backtraces into a structured form
debug.cr (⭐95) - debug!(…) macro for pp-style debugging

Dependency Injection

Athena Dependency Injection (⭐9) - Robust dependency injection service container framework
Crystal-DI (⭐32) - Lightweight DI Container
HardWire (⭐21) - A compile-time non-intrusive dependency injection system
syringe (⭐6) - A simple and basic dependency injection shard for crystal

Email

carbon (⭐84) - Fun, testable, and adapter-based email library
crystal-email (⭐111) - Simple e-mail sending library
CrystalEmail - A RFC compliant Email validator
sendgrid.cr (⭐16) - Simple Sendgrid Client

Environment Management

asdf-crystal (⭐73) - Plugin for asdf version manager
crenv (⭐238) - Crystal version manager
rcm.cr (⭐45) - Redis Cluster Manager
vfox-crystal (⭐5) - Plugin for vfox version manager

Examples and funny stuff

blackjack-cr (⭐8) - Console Blackjack
crystal-patterns (⭐294) - Examples of GOF patters
crystalworld (⭐43) - realworld.io back-end API implementation
exercism-crystal (⭐75) - Exercism exercises
try.cr (⭐26) - Try monad

Framework Components

Athena Event Dispatcher (⭐13) - A Mediator and Observer pattern event library
Athena Negotiation (⭐4) - Framework agnostic content negotiation library
device_detector (⭐22) - Shard for detect device by user agent string
Exception Page (⭐64) - An exceptional exception page for Crystal web libraries and frameworks
graphql (⭐134) - Type-safe GraphQL server implementation
graphql-crystal (⭐215) - GraphQL implementation
kemal-session (⭐53) - Session handler for Kemal
mochi (⭐25) - Authentication shard inspired by Devise supporting: Authenticable, Confirmable, Invitable & more
motion.cr (⭐54) - Object oriented frontend library for Amber
multi-auth (⭐111) - Standardized multi-provider OAuth2 authentication (inspired by omniauth)
praetorian (⭐59) - Minimalist authorization library inspired by Pundit
Shield (⭐55) - Comprehensive security for Lucky framework
shrine.cr (⭐74) - File Attachment toolkit for Crystal applications. Heavily inspired by Shrine for Ruby
tourmaline (⭐157) - Telegram bot framework with an API loosely based on telegraf.js

Game Development

CrSFML (⭐348) - Bindings to SFML multimedia/game library
crystal-chipmunk (⭐43) - Bindings to Chipmunk, a fast and lightweight 2D game physics library
crystal-imgui-sfml (⭐17) - Bindings to integrate Dear ImGui (⭐58k) into an SFML project
entitas.cr (⭐37) - A Entity Component System Framework for Crystal
MyECS (⭐21) - A Sparse Entity Component System Framework for Crystal
Raylib-cr (⭐78) - Direct bindings to Raylib, which supports Linux, Windows, and Mac
SDL-Crystal-Bindings (⭐6) - Direct (unsafe) bindings to SDL2, intended for writing own game libraries

GUI Development

crystal-imgui (⭐67) - Bindings to Dear ImGui (⭐58k), an immediate-mode graphical UI library
GTK4.cr (⭐99) - Bindings for GTK4 with Crystalized API
Iu (⭐72) - UI framework based on the Fusion/libui.cr (⭐177) library, with custom elements and modified bindings from hedron-crystal/hedron (⭐86)
Ultimate GTK4 Crystal Guide - Learn how to create premium GTK4 apps in Crystal

HTML Builders

blueprint (⭐40) - Write reusable and testable HTML templates in plain Crystal
form_builder.cr (⭐31) - Dead simple HTML form builder for Crystal with built-in support for many popular UI libraries such as Bootstrap
to_html (⭐10) - The fastest HTML builder engine for Crystal
Water (⭐27) - A library for writing HTML in plain Crystal

HTML/XML Parsing

docx_cr_converter (⭐7) - parse DOCX Word
myhtml (⭐154) - Fast HTML5 Parser that includes CSS selectors

HTTP

Cable (⭐127) - An ActionCable "port" to Crystal, framework agnostic, 100% compatible with the ActionCable JS Client
cossack (⭐106) - Simple flexible HTTP client
crest (⭐234) - Simple HTTP and REST client, inspired by the Ruby's RestClient gem
crul (⭐113) - Command line HTTP client
digest-auth (⭐4) - Digest authentication
halite (⭐173) - Crystal HTTP Requests with a chainable REST API, built-in sessions and loggers
http-multiserver.cr (⭐23) - Mounting multiple servers via routes (a.k.a. URL mapping)
http-params-serializable (⭐21) - HTTP params (de)serialization, applicable to URL queries and URL-encoded forms
http-protection (⭐72) - Protection against typical web attacks
http2 (⭐94) - HTTP/2 Protocol Implementation
HTTP::Client - HTTP client (Crystal stdlib)
HTTP::Server - HTTP server (Crystal stdlib)
HTTP::WebSocket - HTTP WebSocket client (Crystal stdlib)
link-header (⭐1) - HTTP Link Header Parser
ntlm (⭐4) - NTLM authentication
proxy-fetcher.cr (⭐9) - Proxy lists fetching & validating library
sse.cr (⭐22) - Server-Sent Events client

Image processing

celestine (⭐92) - Create SVG images using a DSL
ffmpeg (⭐19) - FFmpeg bindings that works with StumpyPNG to extract frames
Pluto (⭐67) - A fast and convenient image processing library
stumpy_png (⭐106) - Read and write PNG images

Implementations/Compilers

charly - Charly Programming Language
cltk (⭐73) - A crystal port of the Ruby Language Toolkit
crisp (⭐43) - Lisp dialect implemented with Crystal
LinCAS-lang - A programming language for scientific computation
mint-lang (⭐4k) - 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
novika (⭐15) - A free-form, moldable, interpreted programming language
runic-lang - In-design toy language

Internationalization

crystal-i18n (⭐24) - An internationalization library inspired by Ruby-I18n
i18n.cr (⭐22) - Internationalization shard
Lens (⭐16) - A multiformat internationalization (i18n) shard for Crystal. Supports Gettext, Ruby YAML, etc.
Rosetta (⭐39) - A blazing fast internationalization (i18n) library with compile-time key lookup supporting YAML and JSON formats

Logging and monitoring

crafana (⭐21) - A Grafana library to help autogenerate dashboards
fiber_metrics.cr (⭐8) - Track run time, wait time, or memory allocations per Fiber, method or block
Log - logging utility (Crystal stdlib)
statsd.cr (⭐33) - Statsd (⭐18k) client library

Machine Learning

ai4cr (⭐28) - Artificial Intelligence (based on https://github.com/SergioFierens/ai4r (⭐713))
Cadmium (⭐202) - NLP library based heavily on natural (⭐11k)
crystal-fann (⭐83) - FANN (Fast Artifical Neural Network) binding
mxnet.cr (⭐22) - Bindings for MXNet
shainet (⭐181) - SHAInet (Neural Network in pure crystal)

Markdown/Text Processors

cr-cmark-gfm (⭐20) - Crystal C bindings for cmark-gfm to work with Commonmark and Github Flavored Markdown
markd (⭐109) - Yet another markdown parser built for speed, Compliant to CommonMark specification

Misc

aasm.cr (⭐51) - Easy to use finite state machine for Crystal classes
any_hash.cr (⭐35) - Recursive Hash with better JSON::Any included
anyolite (⭐160) - Full mruby interpreter with simple bindings, allowing for easy scripting support in projects
burocracia.cr (⭐20) - burocracia.cr the dependecyless shard to validate, generate and format Brazilian burocracias such as CPF, CNPJ and CEP
callbacks (⭐12) - Expressive callbacks module
circuit_breaker (⭐27) - Implementation of the circuit breaker pattern
CrSignals (⭐10) - Signals/slots notification library
crystal-binary_parser (⭐18) - Binary parser
crystal-web-framework-stars (⭐70) - Web frameworks for Crystal, most starred on Github
crz (⭐90) - Functional programming library
defined (⭐17) - macros for conditional compilation based on constant definitions, version requirements, or environment variable settings
emoji.cr (⭐47) - Emoji library
gphoto2-web.cr (⭐11) - Web API for libgphoto2
immutable (⭐203) - Implementation of thread-safe, persistent, immutable collections
iterm2 (⭐6) - Display images within the terminal using the ITerm2 Inline Images Protocol
monads (⭐46) - Monad implementation
observable (⭐9) - Implementation of the observer pattern
pinger (⭐11) - Ping IP addresses and DNS entries without requiring sudo
port_midi (⭐6) - Crystal C bindings for the PortMIDI cross-platform MIDI I/O library
retriable.cr (⭐41) - Simple DSL to retry failed code blocks
serf-handler.cr (⭐1) - Framework for building Serf handlers, with a suite of useful builtin capabilities
simple_retry (⭐6) - Simple tool for retrying failed code blocks
sslscan.cr (⭐10) - Crystal shard wrapping the rbsec/sslscan utility
version_tools (⭐8) - Version-dependent behaviour, specified at compile-time
wafalyzer (⭐33) - Web Application Firewall (WAF) Detector - shard + cli
zaru_crystal (⭐10) - Filename sanitization

Network Protocols

amqp-client.cr (⭐69) - AMQP 0-9.1, a messaging protocol, implemented by eg. RabbitMQ
connect-proxy (⭐6) - Connect method style of HTTP tunnelling / HTTP proxy
cr-xmpp (⭐16) - XMPP/Jabber Library
Crirc (⭐21) - IRC protocol implementation (Client, Server, Bots)
crystal-bacnet (⭐0) - BACnet protocol implementation with BACnet/IP client
crystal-dns - DNS protocol implementation and resolver
crystal-json-socket (⭐13) - JSON-socket client & server implementation. Inspired by and compatible with node-json-socket (⭐154) and ruby-json-socket (⭐4)
crystal-mqtt (⭐19) - A MQTT client
crystal-snmp (⭐16) - An SNMP implementation with version 1, 2c and 3 support
fast_irc.cr (⭐22) - Fast IRC parser/generator
jwt (⭐205) - Implementation of JWT (JSON Web Token)
knx (⭐2) - KNX protocol implementation supporting multicast, unicast and TCP/IP tunnelling
mDNS (⭐8) - DNS Service Discovery and multicast DNS
mqtt-client.cr (⭐3) - A fast and lightweight MQTT client
msgpack-crystal (⭐134) - MessagePack library
OAuth - OAuth consumer (Crystal stdlib)
OAuth2 - OAuth2 client (Crystal stdlib)
OpenSSL - bindings to libssl (Crystal stdlib)
simple_rpc (⭐65) - RPC Server and Client for Crystal. Implements msgpack-rpc protocol
stomp (⭐1) - STOMP protocol
telnet.cr (⭐11) - Telnet protocol
transfer_more - Clone of transfer.sh to uploads files

Networking

ipaddress.cr (⭐43) - Library to handle IPv4 and IPv6 addresses
mac-address (⭐2) - Library for working with MAC addresses

ORM/ODM Extensions

avram (⭐165) - A database wrapper for reading, writing, and migrating Postgres databases
clear (⭐268) - ORM specialized to PostgreSQL only but with advanced features
crecto (⭐343) - Database wrapper, based on Ecto
granite (⭐295) - ORM for Postgres, Mysql, Sqlite
jennifer.cr (⭐415) - Active Record pattern implementation with flexible query chainable builder and migration system
rethinkdb-orm (⭐24) - ORM for RethinkDB / RebirthDB

Package Management

shards (⭐758) - Dependency manager for the Crystal

Processes and Threads

await_async (⭐82) - Add keywords await & async in Crystal Lang
concurrent.cr (⭐47) - Simplified concurrency using streams/pipelines, waitgroups, semaphores, smores and more
neph (⭐203) - A modern command line job processor that can execute jobs concurrently
promise (⭐40) - A Promise implementation with type inference
werk (⭐26) - Dead simple task runner with concurrent support, ideal for local CI

Project Generators

crystal_lib (⭐139) - Automatic binding generator for native libraries
fez (⭐49) - A Kemal application generator
libgen (⭐78) - Automatic bindings generator configured using JSON/YAML files

Queues and Messaging

crafka (⭐17) - Apache Kafka library utilizing librdkafka
mosquito (⭐225) - Redis backed periodic and ad hoc job processing
NATS.io (⭐44) - NATS client
sidekiq.cr (⭐767) - Simple, efficient job processing

Routing

orion (⭐124) - A minimal, rails-esque routing library
router.cr (⭐263) - Minimum but powerful http router for HTTP::Server

Scheduling

crystime - Advanced time, calendar, schedule, and remind library
schedule.cr (⭐74) - Run periodic tasks
tasker (⭐55) - A high precision scheduler including timezone aware cron jobs

Science and Data analysis

alea (⭐12) - Repeatable sampling, CDF and other utilities to work with probability distributions
ishi (⭐48) - Graph plotting package with a small API and sensible defaults powered by gnuplot
linalg (⭐47) - Linear algebra library inspired by MATLAB and SciPy.linalg
num.cr (⭐148) - Numerical computing library supporting N-Dimensional data
predict.cr (⭐17) - Satellite prediction library using the sgp4 model
quartz (⭐15) - Modeling and simulation framework

Search

hermes (⭐37) - Data Mapper pattern implementation for ElastiSearch

Serverless Computing

crystal_openfaas (⭐22) - Template to enable crystal as first class citizens in OpenFaaS
secrets-env (⭐6) - Extends ENV module to read values injected by docker / kubernetes secrets and other orchestration tools

System

baked_file_system (⭐177) - Virtual file system implementation
hardware (⭐72) - Get CPU, Memory and Network informations of the running OS and its processes

Task management

cake (⭐71) - Production-ready Make-like utility tool
sam (⭐95) - Another one Rake-like task manager with namespacing and arguments system

Template Engine

crinja (⭐121) - An implementation of the Jinja2 template engine
crustache (⭐83) - {{Mustache}} for Crystal
ECR (Embedded Crystal) - compile time template language which uses plain crystal expressions (Crystal stdlib)
Jbuilder (⭐44) - Generate JSON objects with a Builder-style DSL, inspired by jbuilder
Kilt (⭐152) - Abstraction layer for template engines
Slang (⭐235) - Lightweight, terse, templating language inspired by Ruby's Slim
teeplate (⭐16) - A library for rendering multiple template files

Testing

Athena Spec (⭐2) - Common/helpful Spec compliant testing utilities
crotest (⭐28) - A tiny and simple test framework
crytic (⭐66) - Mutation testing framework
hashr (⭐0) - A tiny class makes test on JSON response easier
LuckyFlow (⭐51) - Automated browser tests similar to Capybara
mass-spec (⭐8) - Web API testing library
microtest (⭐31) - Small opinionated testing library focusing on power asserts
minitest.cr (⭐146) - Library for unit tests and assertions
mocks.cr (⭐52) - Mocking library for Crystal
selenium.cr (⭐23) - Selenium client for interacting with web pages for browser automation
Spec - spec framework (Crystal stdlib)
spectator - Feature rich spec framework that uses the modern expect syntax
timecop.cr (⭐19) - Library for mocking with Time.now. Inspired by the timecop ruby gem (⭐3.3k)
vcr (⭐58) - A HTTP capture and replay implementation for crystal
webdriver_pump (⭐4) - Page Object library. Inspired by Ruby's WatirPump (⭐16)
webmock.cr (⭐103) - Library for stubbing HTTP::Client requests

Third-party APIs

amazonite (⭐0) - An unofficial SDK supporting popular AWS APIs
aws-signer.cr (⭐13) - This library signs your HTTP requests using AWS v4
awscr-s3 (⭐81) - AWS S3 interface
awscr-signer (⭐22) - Sign HTTP::Request objects and generate presigned post forms
crystal-consul (⭐17) - Consul API client
crystal-darksky (⭐8) - Wrapper for the Dark Sky API
crystal-swapi (⭐4) - Star Wars API (SWAPI) wrapper
crystal_slack (⭐19) - A tool that parses Slack slash commands or send incoming web hooks
GDAX (⭐7) - GDAX REST and WebSocket API Wrapper with request signing
gitlab.cr (⭐29) - GitLab API wrapper
google (⭐25) - Google API wrapper
host_meta (⭐3) - A Web Host Metadata (https://tools.ietf.org/html/rfc6415) client
kube-client.cr (⭐22) - Kubernetes API Client
mixpanel-crystal (⭐0) - A library for sending events to Mixpanel
mollie.cr (⭐18) - Mollie Payments API wrapper (Creditcard, PayPal, Apple Pay, Sofort, Klarna, ...)
office365 (⭐8) - Microsoft Graph API wrapper
pinboard.cr (⭐5) - Pinboard API
raven.cr (⭐120) - Raven is a client for Sentry (⭐38k)
stripe.cr (⭐48) - Stripe api wrapper
tmdb.cr (⭐3) - The Movie DB (TMDb) api wrapper
twitter-crystal (⭐82) - A library to access the Twitter API
web_finger (⭐9) - A WebFinger (https://tools.ietf.org/html/rfc7033) client
ynab.cr (⭐4) - A library to interact with your YNAB data

Validation

accord (⭐24) - Shareable validation library for Crystal Objects
Athena Validator (⭐5) - Robust & flexible validation framework
validations (⭐13) - Validations mixin
validator (⭐29) - Data check and validation

Web Frameworks

amber (⭐2.6k) - Open source efficient and cohesive web application framework
Athena (⭐207) - A web framework comprised of reusable, independent components
grip (⭐274) - The microframework for writing powerful web applications
kemal (⭐3.6k) - Lightning Fast, Super Simple web framework. Inspired by Sinatra
lucky (⭐2.6k) - Catch bugs early, forget about most performance issues, and spend more time on code instead of debugging and writing tests
marten (⭐396) - A web framework that makes building web applications easy, productive, and fun
runcobo (⭐49) - An api framework with simple, intuitive and consistent DSL, using jbuilder to render json
Shivneri (⭐23) - Component based MVC web framework for crystal targeting good code structures, modularity & performance
spider-gazelle (⭐179) - A Rails esque web framework with a focus on speed and extensibility

Community

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 Shards for Ruby Gems (⭐19k) - A list of Ruby Gems and their Crystal Shards equivalents
crystal-koans (⭐46) - Learn Crystal by writing unit tests
crystal-lang.org - Official language site
devdocs.io - API Documentation Browser with Crystal support
Learn X in Y minutes - Quick tutorial on Crystal
Programming Crystal - PragProg book to start your Crystal journey
Usability of Programming Languages - Comparison of Python, Rust, Crystal

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 (⭐50) - A Procfile-based application manager (like Foreman)
cry (⭐34) - 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
DeBot (⭐35) - IRC bot written in Crystal
icr (⭐502) - Interactive console for Crystal (like IRB for Ruby)
Invidious (⭐16k) - Invidious is an alternative front-end to YouTube
mpngin (⭐32) - A URL shortener with simple stats
procodile (⭐6) - Run processes in the background (and foreground) on Mac & Linux from a Procfile (for production and/or development environments)
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 (⭐38)

Tools

ast_helper (⭐25) - Helper tool to debug parser and formatter
crystal-base (⭐2) - CentOS base docker image for Crystal development
crystal-dash-docset (⭐17) - Dash docset generator
port_ruby_to_crystal (⭐9) - A regex replace ruby script for port ruby code to crystal easier, reduce friction
public_suffix (⭐2) - A small library designed to make the Public Suffix List (https://publicsuffix.org/) easier to use

DevOps

ansible-crystal (⭐9) - Ansible playbook for installing crystal
DPPM (⭐116) - An easy, universal way to install and manage applications as packages (mostly Linux)

Editor Plugins

Acme:
- acmecrystal (⭐6) - Reformats crystal code in acme
Atom
- crystal-tools - Enables built in tools in Crystal compiler
- language-crystal-actual - Crystal language support in Atom
Emacs
- crystal-mode - Crystal language support for Emacs (crystal-lang-tools/emacs-crystal-mode (⭐47))
Geany
- geany-crystal (⭐9) - Crystal support for the Geany editor
IntelliJ IDEA
- intellij-crystal-lang (⭐38) - Crystal support for the JetBrains IDEs
Lite-XL
- lite-plugin-crystal (⭐6) - Crystal support for the Lite-XL editor
Spacemacs
- crystal-spacemacs-layer (⭐12) - Spacemacs contribution layer for Crystal
Sublime
- sublime-crystal (⭐84) - Crystal syntax highlighting for sublime Text
TextMate
- Crystal.tmbundle (⭐18) - Crystal syntax highlighting, compile, format command, snippets
Vim
- vim-crystal (⭐412) - Vim filetype support for Crystal
- vim-slang (⭐12) - Vim filetype support for Slang Templating Engine
Visual Studio Code
- vscode-crystal-lang (⭐275) - Formatter, linter and syntax highlighting for cr and ecr files

LSP Language Server Protocol Implementations

crystalline (⭐428) - Crystalline is an implementation of the Language Server Protocol written in and for the Crystal Language
scry (⭐333) - Code analysis server for Crystal implementing the Language Server Protocol

Shell plugins

crun (⭐43) - Crystal Run : shebang wrapper for Crystal
crystal-zsh (⭐28) - .oh-my-zsh plugin