@fedify/uri-template: RFC 6570 URI Template implementation

This package provides RFC 6570 fully compliant URI template expansion and pattern matching library. Supports symmetric matching where expand(match(url)) and match(expand(vars)) behave predictably.

Features

• Full RFC 6570 Level 4 support: Handles all operators and modifiers (explode *, prefix :n)
• Symmetric pattern matching:
  • opaque: byte-for-byte exact round-trips
  • cooked: human-readable decoded values
  • lossless: preserves both raw and decoded forms
• Strict percent-encoding validation: Prevents malformed sequences (%GZ, etc.)
• Deterministic expansion: Correctly handles undefined/empty values per RFC rules

Installation

deno add jsr:@fedify/uri-template  # Deno
npm  add     @fedify/uri-template  # npm
pnpm add     @fedify/uri-template  # pnpm
yarn add     @fedify/uri-template  # Yarn
bun  add     @fedify/uri-template  # Bun

Usage

import { compile } from "@fedify/uri-template";

const tmpl = compile("/repos{/owner,repo}{?q,lang}");

// Expansion
const url = tmpl.expand({ owner: "foo", repo: "hello/world", q: "a b" });
// => "/repos/foo/hello%2Fworld?q=a%20b"

// Matching
const result = tmpl.match("/repos/foo/hello%2Fworld?q=a%20b", {
  encoding: "cooked"
});
// => { owner: "foo", repo: "hello/world", q: "a b" }

Matching options:

• encoding: "opaque" (default, preserves raw) | "cooked" (decoded) | "lossless" (both)
• strict: true (default, strict) | false (lenient parsing)

Documentation

For detailed implementation details, see specification.md.