diff --git a/test/canvasAPI.js b/test/canvasAPI.js
index 0979518..38d8f21 100644
--- a/test/canvasAPI.js
+++ b/test/canvasAPI.js
@@ -2,8 +2,8 @@ const canvasAPI = {
 	draw: function draw(canvas){
 		"use strict";
 		
-		canvas.setAttribute("width", 220);
-		canvas.setAttribute("height", 30);
+		canvas.width = 220;
+		canvas.height = 30;
 		
 		const fingerprintText = "BrowserLeaks,com <canvas> 10";
 		
diff --git a/test/test.html b/test/test.html
index c2814fd..4c51cb3 100644
--- a/test/test.html
+++ b/test/test.html
@@ -71,6 +71,24 @@
 	Hash: <span class="hash"><i>click anywhere to populate</i></span> (isPointInPath: <span class="isPointInPath"></span>)
 	<button>refresh</button>
 </div>
+<div id="blob">
+	<h3>blob Test</h3>
+	<img class="display"><br>
+	Hash: <span class="hash"></span>
+	<button>refresh</button>
+</div>
+<div id="offscreen">
+	<h3>offscreen Test</h3>
+	<img class="display"><br>
+	Hash: <span class="hash"></span>
+	<button>refresh</button>
+</div>
+<div id="offscreenWorker">
+	<h3>offscreen Worker Test</h3>
+	<img class="display"><br>
+	Hash: <span class="hash"></span>
+	<button>refresh</button>
+</div>
 <script src="testAPI.js"></script>
 <script src="canvasAPI.js"></script>
 <script src="test.js"></script>
diff --git a/test/test.js b/test/test.js
index 91aba09..a5714b8 100644
--- a/test/test.js
+++ b/test/test.js
@@ -8,12 +8,14 @@
 		display.title = url;
 		const hashes = await Promise.all([
 			testAPI.hash(url),
-			testAPI.hash(imageData.data)
+			imageData? testAPI.hash(imageData.data): ""
 		]);
 		container.querySelector(".hash").textContent =
 			hashes[0] + " / " +
 			hashes[1];
-		container.querySelector(".isPointInPath").textContent = isPointInPath;
+		if (typeof isPointInPath === "boolean"){
+			container.querySelector(".isPointInPath").textContent = isPointInPath;
+		}
 	}
 	
 	function iframeTest(testNode){
@@ -51,15 +53,47 @@
 				newWindow.close();
 				return fingerprint;
 			}
-		}
+		},
+		blob: async function(testNode){
+			const canvas = document.createElement("canvas");
+			canvasAPI.draw(canvas);
+			return new Promise(function(resolve, reject){
+				canvas.toBlob(async function(blob){
+					resolve({url: await testAPI.readBlob(blob)});
+				});
+			});
+		},
+		offscreen: async function(testNode){
+			if (typeof OffscreenCanvas === "undefined"){
+				throw "not supported";
+			}
+			return offscreenTest();
+		},
+		offscreenWorker: async function(testNode){
+			if (
+				typeof OffscreenCanvas === "undefined" ||
+				typeof Worker === "undefined"
+			){
+				throw "not supported";
+			}
+			const canvasAPIUrl = new URL("./canvasAPI.js", location);
+			const testAPIUrl = new URL("./testAPI.js", location);
+			return testAPI.runInWorker(offscreenTest, [], [canvasAPIUrl, testAPIUrl]);
+		},
 	};
 	
 	Object.keys(tests).forEach(async function(testName){
 		const testNode = document.getElementById(testName);
 		const callback = tests[testName];
 		if (location.search !== "?notInitial"){
-			try {show(testNode, await callback(testNode, true));}
-			catch (error){console.error(testName, error);}
+			try {
+				show(testNode, await callback(testNode, true));
+			}
+			catch (error){
+				testNode.querySelector(".hash").innerHTML =
+					"<i>Error while computing: " + (error.message || error) + "</i>";
+				console.error(testName, error);
+			}
 		}
 		testNode.querySelector("button").addEventListener("click", async function(){
 			show(testNode, await callback(testNode));
@@ -99,4 +133,16 @@ function dynamicIframeTest3(){
 	const iframeWindow = window[length];
 	document.body.removeChild(div);
 	return canvasAPI.fingerprint(iframeWindow);
+}
+
+async function offscreenTest(){
+	"use strict";
+	
+	const offscreenCanvas = new OffscreenCanvas(220, 30);
+	canvasAPI.draw(offscreenCanvas);
+	const blob = offscreenCanvas.convertToBlob?
+		await offscreenCanvas.convertToBlob():
+		await offscreenCanvas.toBlob();
+	
+	return {url: await testAPI.readBlob(blob)};
 }
\ No newline at end of file
diff --git a/test/testAPI.js b/test/testAPI.js
index e09b036..fe96f47 100644
--- a/test/testAPI.js
+++ b/test/testAPI.js
@@ -18,6 +18,54 @@ const testAPI = function(){
 	
 	
 	return {
+		runInWorker: async function(func, args = [], scripts = []){
+			return new Promise(function(resolve, reject){
+				const apis = scripts.map(function(script){
+					switch (typeof script){
+						case "function":
+							return script.toString();
+						case "string":
+						case "object":
+							return "self.importScripts(" + JSON.stringify(script.toString()) + ")";
+						default:
+							return "";
+					}
+				}).join(";\n");
+				const code = `${apis};
+				${func.toString()}
+				async function run(){
+					return ${func.name}(${args.map(JSON.stringify).join(", ")});
+				}
+				run().then(function(result){
+					self.postMessage({result});
+				}).catch(function(error){
+					console.log(error);
+					self.postMessage({error: error.message || error.toString()});
+				});`;
+				const blob = new Blob([code], {type: "text/javascript"});
+				
+				const blobWorker = new Worker(URL.createObjectURL(blob), {name: "BlobWorker"});
+				blobWorker.addEventListener("message", function(event){
+					if (event.data.error){
+						reject(event.data.error);
+					}
+					else {
+						resolve(event.data.result);
+					}
+					blobWorker.terminate();
+				});
+			});
+		},
+		readBlob: async function(blob){
+			const reader = new FileReader();
+			return new Promise(function(resolve, reject){
+				reader.addEventListener("error", reject);
+				reader.addEventListener("load", function(){
+					resolve(reader.result);
+				});
+				reader.readAsDataURL(blob);
+			});
+		},
 		hash: async function(input){
 			const buffer = ((typeof input) === "string")?
 				new TextEncoder("utf-8").encode(input):