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💎 A collection of awesome Crystal libraries, tools, frameworks and


veelengaveelenga/awesome-crystalUpdated Fresh 2073 126 215


Awesome Crystal

Awesome Build Status

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

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

Contributions are welcome. Please take a quick look at the contribution guidelines first.

Algorithms and Data structures

  • aho_corasick - AhoCorasick algorithm
  • bisect - Inserting values into a sorted array
  • bitfields - Pure Crystal implementation of BitFields. Handles encoding/decoding of bytes.
  • CrOTP - HOTP and TOTP implementation for two factor authentication
  • crystal-diff - A Crystal sequence differencing implementation
  • 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
  • delimiter_tree - A tree structure that is built using a delimiter
  • - Collection of edit distance algorithms
  • graphlb - Collection of graph datastructure and algorithms
  • hash_ring - An Implementation of Consistent Hash Ring
  • - K-Sortable Globally Unique IDs
  • markov - Build Markov Chains and run Markov Processes
  • - Implementation of a multiset
  • murmur3 - Implementation of Murmur3 hash algorithm used by Cassandra
  • oak - A flexible Radix Tree implementation
  • radix - Radix Tree implementation
  • ternary_search_tree - Ternary Search Tree

Api Builders


C bindings


  • bloom_filter - Implementation of Bloom filter
  • bojack - A non-reliable in-memory key-value store
  • cache-hash - A key/value store where entries expire after a specified interval
  • crystal-memcached - Implementation of a memcached client
  • Nuummite - A tiny persistent embedded key-value store

CLI Builders

  • admiral - A robust DSL for writing command line interfaces
  • cli - Library for building command-line interface applications
  • clicr - A simple declarative command line interface builder
  • clim - Slim command line interface builder
  • commander - Command-line interface builder
  • completion - Easy command line completion engine
  • optarg - Yet another library for parsing command-line options and arguments
  • OptionParser - command-line options processing (Crystal stdlib)

CLI Utils

Code Analysis and Metrics

  • ameba - A static code analysis tool
  • trashman - A simple memory profiler for Crystal applications


  • cr-dotenv - Loads .env file
  • 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


  • - Base62 encoder/decoder, well suited for url-shortening
  • money - Handling money and currency conversion with ease (almost complete port of RubyMoney)
  • moola - Library for dealing with money and conversion (inspired by RubyMoney)
  • ms - Library to easily convert various time formats to milliseconds and milliseconds to human readable format
  • - Compile SASS/SCSS to CSS (libsass binding)
  • - Convert time in human readable format with ease
  • turkish-number - Turn integers into the Turkish words
  • wkhtmltopdf-crystal - Bindings / wrapper for libwkhtmltox (HTML to PDF / image converter)

Data Formats

  • - Easy to use configuration format parser
  • crinder - Class based json renderer
  • CSV - parsing and generating for comma-separated values (Crystal stdlib)
  • - Separates a files front matter from its content
  • Gzip - readers and writers of gzip format (Crystal stdlib)
  • INI - INI file parser (Crystal stdlib)
  • JSON - parsing and generating JSON documents (Crystal stdlib)
  • - parsing MaxMindDB files, including the GeoIP2
  • - TOML parser
  • XML - parsing and generating XML documents (Crystal stdlib)
  • YAML - parsing and generating YAML documents (Crystal stdlib)
  • Zip - readers and writers of zip format (Crystal stdlib)
  • Zlib - readers and writers of zlib format (Crystal stdlib)
  • zq - Command-line ZPL processor

Data Generators

  • faker - A library for generating fake data
  • - A library to generate YouTube-like ids from one or many numbers

Database Drivers/Clients

Database Tools

  • crecto-admin - Admin dashboard for Crecto and your database
  • micrate - Database migration tool
  • migrate - A simpler database migration tool with transactions
  • migro - A database migration tool that allows migrations to be specified in either YAML or raw SQL

Development Tools

  • guardian - File change watcher for Crystal and Non-Crystal libs
  • kemal-watcher - Kemal plugin to watch files and live-reload the browser
  • sentry - Watches src files, rebuilds/reruns application on file changes
  • sentry-run - Reload code changes using
  • Warden - Watches files, run command and a git command if succeed on file changes
  • watcher - Watch file changes using File.stat


  • carbon - Fun, testable, and adapter-based email library
  • crystal-email - Simple e-mail sending library
  • CrystalEmail - A RFC compliant Email validator
  • devmail - A combined SMTP/POP3-server with volatile mail storage
  • - Simple Sendgrid Client

Environment Management

Examples and funny stuff

Feature Flipping

  • flipper - Feature flipping/flags/rollouts. Supports multiple backends

Framework Components

Game Development

  • cray - Bindings for raylib, an easy-to-use game development library
  • CrSFML - Bindings to SFML multimedia/game library
  • crystal-chipmunk - Bindings for Chipmunk, a fast and lightweight 2D game physics library
  • glove - A library for gaming development
  • inari - A collection of games using Glove as the game engine
  • mos_game - Mini Offline Singleplayer game

GUI library

  • hedron - An extendable GUI library, with markup language capabilities
  • - Bindings for libui
  • - Qt5 bindings for Crystal, based on Bindgen

HTML/XML Parsing


  • cossack - Simple flexible HTTP client
  • crest - Simple HTTP and REST client, inspired by the Ruby's RestClient gem
  • crul - Command line HTTP client
  • cryload - HTTP benchmarking tool
  • halite - Crystal HTTP Requests with a chainable REST API, built-in sessions and loggers
  • helmet - Set security-related HTTP headers
  • - Mounting multiple servers via routes (a.k.a. URL mapping)
  • 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)
  • keyer_cr - Adds HTTP GET/POST parameter parsing as a Hash-like object
  • - Ngrok wrapper
  • params - The strongly-typed HTTP params parsing module
  • resp-crystal - Lightweight RESP client

Image processing


  • charly - Charly Programming Language
  • cibyl - Lightweight curly-bracket language which compiles to Ruby and Crystal
  • cltk - A crystal port of the Ruby Language Toolkit
  • cppize - Crystal-to-C++ transpiler
  • crisp - Lisp dialect implemented with Crystal
  • crow - Transpile/compile Crystal to Flow
  • 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
  • NuummiteOS - An OS written in Crystal as a Proof of Concept
  • runic-lang - In-design toy language

Logging and monitoring

Machine Learning

Markdown/Text Processors

  • html-pipeline - HTML processing filters and utilities
  • markd - Yet another markdown parser built for speed, Compliant to CommonMark specification


  • - Easy to use finite state machine for Crystal classes
  • - Recursive Hash with better JSON::Any included
  • - Library for writing or apppending files atomically
  • - 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
  • compiled_license - Compiles licenses into binary for complience with MIT when copying binary to system or container without the code
  • crystal-binary_parser - Binary parser
  • crz - Functional programming library
  • - Emoji library
  • hoop - Building native OSX apps
  • html_builder - DSL for creating HTML
  • - Internationalization shard
  • immutable - Implementation of thread-safe, persistent, immutable collections
  • - Singularize, pluralize, camelize, etc (port from ActiveSupport)
  • lirith - Graphics engine
  • m3u8 - Generate and parse m3u8 playlists for HTTP Live Streaming
  • manual-generator - Tool to generate PDF manuals from documentation sites
  • - Verify and generate Rails ActiveSupport::MessageVerifier signed tokens
  • raytracer - CPU Raytracer with examples
  • - Simple DSL to retry failed code blocks
  • tren - Give your SQL some love
  • ulid - Universally Unique Lexicographically Sortable Identifier (ULID)

Network Protocols


ORM/ODM Extensions

  • clear - ORM specialized to PostgreSQL only but with advanced features
  • core - Pure, transparent and efficient ORM
  • crecto - Database wrapper, based on Ecto
  • granite - ORM for Postgres, Mysql, Sqlite
  • - Active Record pattern implementation with flexible query chainable builder and migration system
  • ohm-crystal - Object-hash mapping library for Redis
  • record - Type safe querying, saving and updating
  • - Import and export data from Redis in TSV format
  • stal-crystal - Set algebra solver for Redis
  • topaz - A simple and useful db wrapper

Package Management

  • CRelease - Version and git tag manager that makes shard releases easy
  • shards - Dependency manager for the Crystal

Processes and Threads

  • await_async - Add keywords await & async in Crystal Lang
  • crystal-futures - Future type implementation
  • neph - A modern command line job processor that can execute jobs concurrently
  • promise - A Promise implementation with type inference

Project Generators

  • bindgencr - Generator of bindings based on castxml output
  • crystal_lib - Automatic binding generator for native libraries
  • fez - A Kemal application generator
  • kgen - Kemalyst command line tool for console, init, generate (scaffolding), and watch.
  • libgen - Automatic bindings generator configured using JSON/YAML files
  • wasp - Static Site Generator

Queues and Messaging

  • - AMQP 0.9.1 client with RabbitMQ extensions
  • dispatch - In memory asynchronous job processing
  • mosquito - Redis backed periodic and ad hoc job processing
  • - Simple, efficient job processing


  • crouter - A standalone router
  • orion - A minimal, rails-esque routing library
  • - Minimum but powerful http router for HTTP::Server
  • toro - Tree Oriented Routing


  • cron_scheduler - Job scheduler with crontab patterns
  • crystime - Advanced time, calendar, schedule, and remind library
  • - Run periodic tasks
  • tasker - A high precision scheduler including timezone aware cron jobs

Science and Data analysis

  • linalg - Linear algebra library inspired by MATLAB and SciPy.linalg
  • - Satellite prediction library using the sgp4 model
  • stats - An expressive implementation of statistical distributions


  • hermes - Data Mapper pattern implementation for ElastiSearch
  • query-builder - Sql Query Builder library
  • - Query abstraction
  • 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
  • - Managed execution of Crystal in Google Cloud Functions


  • baked_file_system - Virtual file system implementation
  • hardware - Get CPU, Memory and Network informations of the running OS and its processes
  • rcpu - A virtual machine emulator and assembler

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)
  • Kilt - Abstraction layer for template engines
  • Slang - Lightweight, terse, templating language inspired by Ruby's Slim
  • teeplate - A library for rendering multiple template files
  • temel - Extensible HTML::Builder alternative for Crystal, supports custom tag definitions


  • coverage – Generate cover report for your crystal code
  • crotest - A tiny and simple test framework
  • crystal-clear - Design by Contract Library
  • 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
  • - Library for unit tests and assertions
  • - Mocking library for Crystal
  • Spec - spec framework (Crystal stdlib)
  • - Library for mocking with Inspired by the timecop ruby gem
  • - Library for stubbing HTTP::Client requests

Third-party APIs


  • accord - Shareable validation library for Crystal Objects
  • CrSerializer - Extensible annotation based serialization/deserialization/validation library
  • denetmen - Micro check library that patches Crystal stdlib
  • validations - Validations mixin

Web Frameworks

  • amber - Open source efficient and cohesive web application framework
  • kemal - Lightning Fast, Super Simple web framework. Inspired by Sinatra
  • lattice-core - A WebSocket-first object-oriented framework (based on Kemal)
  • lucky - Catch bugs early, forget about most performance issues, and spend more time on code instead of debugging and writing tests
  • prism - Lightspeed web framework with typed params
  • raze - Modular, light web framework
  • spider-gazelle - A Rails esque web framework with a focus on speed and extensibility

Web Servers

  • fast-http-server - Super fast, zero configuration command line HTTP Server
  • - Rack proxy server for development
  • salt - A Human Friendly Interface for HTTP server
  • serve - Command line static HTTP server




Official Documentation Translations

Services and Apps

  • - A web service that runs your code and displays the result
  • 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
  •, - Web services that list all available Crystal shards
  • Crystular - Regular expression tester
  • DeBot - IRC bot written in Crystal
  • Fluence - WYSIWYG wiki using markdown and Git
  • 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
  • nes - A NES emulator
  • quicktype - Generate models and serializers from JSON, JSON Schema, GraphQL, and TypeScript
  • - Web service that lists all repositories on GitHub that have Crystal code in them. The sources are available on GitHub
  • wikicr - Wiki using git to manage revisions



Editor Plugins

Shell plugins

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