For developers, who are building real-time data-driven applications, Redis is the preferred, fastest, and most feature-rich cache, data structure server, and document and vector query engine.

A time-series database for high-performance real-time analytics packaged as a Postgres extension

A fast image processing library with low memory needs.

An open source, portable, easy to use, readable and flexible TLS library, and reference implementation of the PSA Cryptography API. Releases are on a varying cadence, typically around 3 - 6 months …

Nokogiri (鋸) makes it easy and painless to work with XML and HTML from Ruby.

The safe Markdown parser, reloaded.

Optimized JSON

A streaming JSON parsing and encoding library for Ruby (C bindings to yajl)

Prism Ruby parser

Ruby Optimized XML Parser

Ruby extension to parse, deparse and normalize SQL queries using the PostgreSQL query parser

A barcode encoding library supporting over 50 symbologies including Code 128, Data Matrix, USPS OneCode, EAN-128, UPC/EAN, ITF, QR Code, Code 16k, PDF417, MicroPDF417, LOGMARS, Maxicode, GS1 DataBa…

Simple evented I/O for Ruby.

Fine-grained concurrency for Ruby

The Escapist

Ultra Fast Excel Writer for Ruby

High-performance HTML5 parser for Ruby based on Lexbor, with support for both CSS selectors and XPath.

A super fast, efficiently stored Trie for Ruby. Uses libdatrie.

Libxml bindings for Ruby.

Unicode normalization library. (Mirror of Yoshida-san's code base to maintain the RubyGem.)