diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 815d21c..783d11f 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -9,12 +9,12 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [12.x]
+        node-version: [22.x]
 
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v4
     - name: Use Node.js ${{ matrix.node-version }}
-      uses: actions/setup-node@v1
+      uses: actions/setup-node@v4
       with:
         node-version: ${{ matrix.node-version }}
     - name: npm install, build, and test
@@ -24,7 +24,7 @@ jobs:
         npm test
       env:
         CI: true     
-    - uses: actions/upload-artifact@v1
+    - uses: actions/upload-artifact@v4
       with:
         name: dezoomify.zip
         path: ./dezoomify.zip
diff --git a/background.js b/background.js
index ff92fc1..fc7bb82 100644
--- a/background.js
+++ b/background.js
@@ -1,36 +1,3 @@
-const DEZOOMIFY_URL = "https://dezoomify.ophir.dev/#";
-
-const iiifpath = new RegExp( // IIIF API image URL
-    "/\\^?(full|square|(pct:)?\\d+,\\d+,\\d+,\\d+)" + // region
-    "/(full|max|\\d+,|,\\d+|pct:\\d+|!?\\d+,\\d+)" + // size
-    "/!?[1-3]?[0-9]?[0-9]" + // rotation
-    "/(color|gray|bitonal|default|native)" + // quality
-    "\\.(jpe?g|tiff?|png|gif|jp2|pdf|webp)" // format
-);
-
-const META_REGEX = new RegExp([
-    /\/ImageProperties.xml/, // Zoomify
-    /\/info.json/, // IIIF
-    /\?FIF=/, // IIPImage
-    /_files\/0\/0_0.jpg(?:\?.*)?$/, // OpenSeadragon
-    /\.img.\\?cmd=info/,
-    /getTilesInfo\?object_id/,
-    /\.pff(&requestType=1)?$/, // Zoomify PFF
-    /\.ecw(?:\?.*)?$/, // Hungaricana
-    /\/p.xml(?:\?.*)?$/, // Mnesys
-    iiifpath,
-    /artsandculture\.google\.com\/asset\// // Google Arts
-].map(e => e.source).join('|'));
-const META_REPLACE = [
-    { pattern: /\.dzi(?:\?.*)?$/, replacement: '_files/0/0_0.jpg' },
-    { pattern: /_files\/\d+\/\d+_\d+\.jpg(?:\?.*)?$/, replacement: '_files/0/0_0.jpg' },
-    { pattern: /\/TileGroup\d+\/\d+-\d+-\d+.jpg(?:\?.*)?$/, replacement: '/ImageProperties.xml' },
-    { pattern: /\/ImageProperties\.xml\?t\w+$/, replacement: '/ImageProperties.xml' },
-    { pattern: /(\?FIF=[^&]*)&.*/, replacement: '$1' }, // IIPImage
-    { pattern: /(http.*artsandculture\.google\.com\/asset\/.+\/.+)\?.*/, replacement: '$1' },
-    { pattern: iiifpath, replacement: '/info.json' },
-    { pattern: /getTilesInfo\?object_id=(.*)&callback.*/, replacement: 'getTilesInfo?object_id=$1' },
-];
 // @ts-ignore
 const VALID_RESOURCE_TYPES = new Set(Object.values(chrome.webRequest['ResourceType']));
 
@@ -148,12 +115,8 @@ class PageListener {
      * @param {{url:string }} request 
      */
     handleRequest({ url }) {
-        for (const { pattern, replacement } of META_REPLACE) {
-            url = url.replace(pattern, replacement);
-        }
-        if (META_REGEX.test(url) && !url.startsWith(DEZOOMIFY_URL)) {
-            this.foundZoomableImage(url);
-        }
+        const recognizedUrl = recognizeZoomableUrl(url);
+        if (recognizedUrl) this.foundZoomableImage(recognizedUrl);
     }
 
     /**
diff --git a/build.sh b/build.sh
index 6a06254..a43e3fa 100755
--- a/build.sh
+++ b/build.sh
@@ -4,5 +4,5 @@ TMPDIR=$(mktemp -d)
 jq '.version |= '"$version"' ' < manifest.json > "$TMPDIR/manifest.json"
 
 rm -f dezoomify.zip
-zip -r dezoomify.zip icons/ background.js manifest.json
-zip -r --junk-paths dezoomify.zip "$TMPDIR/manifest.json"
\ No newline at end of file
+zip -r dezoomify.zip icons/ url-recognition.js background.js manifest.json
+zip -r --junk-paths dezoomify.zip "$TMPDIR/manifest.json"
diff --git a/manifest.json b/manifest.json
index f02d709..66341c3 100644
--- a/manifest.json
+++ b/manifest.json
@@ -27,7 +27,8 @@
     ],
     "background": {
         "scripts": [
+            "url-recognition.js",
             "background.js"
         ]
     }
-}
\ No newline at end of file
+}
diff --git a/package.json b/package.json
index e472bfc..30cc3df 100644
--- a/package.json
+++ b/package.json
@@ -4,7 +4,7 @@
   "description": "Detect zoomable images in web pages and download them with dezoomify",
   "main": "background.js",
   "scripts": {
-    "test": "tsc",
+    "test": "node test/url-recognition.test.js && tsc",
     "build": "bash -x build.sh"
   },
   "repository": {
diff --git a/test/url-recognition.test.js b/test/url-recognition.test.js
new file mode 100644
index 0000000..791524a
--- /dev/null
+++ b/test/url-recognition.test.js
@@ -0,0 +1,37 @@
+const assert = require("assert");
+const fs = require("fs");
+const vm = require("vm");
+
+const source = fs.readFileSync("url-recognition.js", "utf8");
+const context = {};
+vm.runInNewContext(source, context);
+const recognize = context.recognizeZoomableUrl;
+
+const cases = [
+    ["https://example.com/ImageProperties.xml?t123", "https://example.com/ImageProperties.xml"],
+    ["https://example.com/image/info.json", "https://example.com/image/info.json"],
+    ["https://example.com/image.dzi?cache=1", "https://example.com/image_files/0/0_0.jpg"],
+    ["https://example.com/image_files/12/3_4.jpg?cache=1", "https://example.com/image_files/0/0_0.jpg"],
+    ["https://example.com/image_files/12/3_4.jpeg", "https://example.com/image_files/0/0_0.jpg"],
+    ["https://example.com/TileGroup2/5-3-4.jpg", "https://example.com/ImageProperties.xml"],
+    ["https://example.com/iip?FIF=image.tif&WID=500", "https://example.com/iip?FIF=image.tif"],
+    ["https://example.com/image.imgi?cmd=info", "https://example.com/image.imgi?cmd=info"],
+    ["https://example.com/image.pff", "https://example.com/image.pff"],
+    ["https://example.com/image.ecw", "https://example.com/image.ecw"],
+    ["https://example.com/viewer/p.xml", "https://example.com/viewer/p.xml"],
+    ["https://example.com/id/full/512,/0/default.jpg", "https://example.com/id/info.json"],
+    ["https://www.rijksmuseum.nl/api/getTilesInfo?object_id=1&callback=x", "https://www.rijksmuseum.nl/api/getTilesInfo?object_id=1"],
+    ["https://artsandculture.google.com/asset/title/id?hl=en", "https://artsandculture.google.com/asset/title/id"],
+];
+
+for (const [input, expected] of cases) {
+    assert.strictEqual(recognize(input), expected, input);
+}
+
+assert.strictEqual(recognize("https://example.com/photo.jpg"), undefined);
+assert.strictEqual(
+    recognize("https://dezoomify.ophir.dev/#https://example.com/info.json"),
+    undefined
+);
+
+console.log(`Passed ${cases.length + 2} URL recognition tests`);
diff --git a/tsconfig.json b/tsconfig.json
index 704d8b1..acb2e71 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -14,9 +14,10 @@
     "esModuleInterop": true /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
   },
   "files": [
+    "url-recognition.js",
     "background.js"
   ],
   "types": [
     "chrome"
   ]
-}
\ No newline at end of file
+}
diff --git a/url-recognition.js b/url-recognition.js
new file mode 100644
index 0000000..c1ff27d
--- /dev/null
+++ b/url-recognition.js
@@ -0,0 +1,47 @@
+const DEZOOMIFY_URL = "https://dezoomify.ophir.dev/#";
+
+const iiifpath = new RegExp(
+    "/\\^?(full|square|(pct:)?\\d+,\\d+,\\d+,\\d+)" +
+    "/(full|max|\\d+,|,\\d+|pct:\\d+|!?\\d+,\\d+)" +
+    "/!?[1-3]?[0-9]?[0-9]" +
+    "/(color|gray|bitonal|default|native)" +
+    "\\.(jpe?g|tiff?|png|gif|jp2|pdf|webp)"
+);
+
+const META_REGEX = new RegExp([
+    /\/ImageProperties.xml/,
+    /\/info.json/,
+    /\?FIF=/,
+    /_files\/0\/0_0\.jpe?g(?:\?.*)?$/,
+    /\.img.\?cmd=info/,
+    /getTilesInfo\?object_id/,
+    /\.pff(&requestType=1)?$/,
+    /\.ecw(?:\?.*)?$/,
+    /\/p.xml(?:\?.*)?$/,
+    iiifpath,
+    /artsandculture\.google\.com\/asset\//
+].map(e => e.source).join('|'));
+
+const META_REPLACE = [
+    { pattern: /\.dzi(?:\?.*)?$/, replacement: '_files/0/0_0.jpg' },
+    { pattern: /_files\/\d+\/\d+_\d+\.jpe?g(?:\?.*)?$/, replacement: '_files/0/0_0.jpg' },
+    { pattern: /\/TileGroup\d+\/\d+-\d+-\d+.jpg(?:\?.*)?$/, replacement: '/ImageProperties.xml' },
+    { pattern: /\/ImageProperties\.xml\?t\w+$/, replacement: '/ImageProperties.xml' },
+    { pattern: /(\?FIF=[^&]*)&.*/, replacement: '$1' },
+    { pattern: /(http.*artsandculture\.google\.com\/asset\/.+\/.+)\?.*/, replacement: '$1' },
+    { pattern: iiifpath, replacement: '/info.json' },
+    { pattern: /getTilesInfo\?object_id=(.*)&callback.*/, replacement: 'getTilesInfo?object_id=$1' },
+];
+
+/**
+ * Return a canonical metadata URL when a request belongs to a supported viewer.
+ * @param {string} requestUrl
+ * @returns {string | undefined}
+ */
+function recognizeZoomableUrl(requestUrl) {
+    let url = requestUrl;
+    for (const { pattern, replacement } of META_REPLACE) {
+        url = url.replace(pattern, replacement);
+    }
+    if (META_REGEX.test(url) && !url.startsWith(DEZOOMIFY_URL)) return url;
+}