How Unicode Collation Works (2025)
The article explains the Unicode Collation Algorithm (UCA), a standardized method for sorting text that goes beyond the basic Latin alphabet by handling accented characters, different scripts, and case variations. It outlines how simple byte-level sorting fails with Unicode characters like 'É' and describes the steps UCA uses, such as normalization and sort key generation, to enable accurate linguistic sorting. The author also references their own implementations of UCA in Rust and Zig, along with a web tool demonstrating collation differences.
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How Unicode Collation Works Theodore Beers August 2025 (updated April 2026) This post is an introduction to the Unicode Collation Algorithm (UCA), a standardized solution to a problem that turns out to be somewhat complex: how can we alphabetically sort items of text when the characters go beyond the basic Latin alphabet? Let’s find out… Sidebar: I maintain a minimalistic but conformant & performant implementation of the UCA in Rust, called feruca ; and I recently adapted it to Zig, in a library called later . Code examples in this post will be in Zig. You may also like to visit my “Text Sorting Playground ,” a little web app that demonstrates the differences among a few approaches to collation.
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