diff --git a/.changeset/soft-melons-kiss.md b/.changeset/soft-melons-kiss.md
new file mode 100644
index 0000000000..1317af7ac9
--- /dev/null
+++ b/.changeset/soft-melons-kiss.md
@@ -0,0 +1,5 @@
+---
+'singleton-manager': patch
+---
+
+add node/ssr support
diff --git a/packages/singleton-manager/package.json b/packages/singleton-manager/package.json
index 883cd91904..5b41152ba8 100644
--- a/packages/singleton-manager/package.json
+++ b/packages/singleton-manager/package.json
@@ -35,6 +35,7 @@
     "start:singleton": "es-dev-server -c demo/singleton/server.js",
     "start:singleton-complex": "es-dev-server -c demo/singleton-complex/server.js",
     "test": "cd ../../ && npm run test:browser -- --group singleton-manager",
+    "test:node": "mocha test-node",
     "types": "wireit"
   },
   "keywords": [
diff --git a/packages/singleton-manager/src/SingletonManagerClass.js b/packages/singleton-manager/src/SingletonManagerClass.js
index 6a10af55f7..7cf4ae3350 100644
--- a/packages/singleton-manager/src/SingletonManagerClass.js
+++ b/packages/singleton-manager/src/SingletonManagerClass.js
@@ -1,9 +1,18 @@
 const sym = Symbol.for('lion::SingletonManagerClassStorage');
 
+/**
+ * Allow compatibility with node-js (for ssr).
+ * In the future, we can just use globalThis directly
+ * (for now, we're backwards compatible with browsers that still only use window, since we don't know all contexts singleton-manager is used in).
+ */
+// eslint-disable-next-line no-undef
+const globalThisOrWindow = globalThis || window;
 export class SingletonManagerClass {
   constructor() {
     /** @protected */
-    this._map = window[sym] ? window[sym] : (window[sym] = new Map());
+    this._map = globalThisOrWindow[sym]
+      ? globalThisOrWindow[sym]
+      : (globalThisOrWindow[sym] = new Map());
   }
 
   /**
diff --git a/packages/singleton-manager/test-node/SingletonManagerClass.test.js b/packages/singleton-manager/test-node/SingletonManagerClass.test.js
new file mode 100644
index 0000000000..cbc83a1432
--- /dev/null
+++ b/packages/singleton-manager/test-node/SingletonManagerClass.test.js
@@ -0,0 +1,4 @@
+import { expect } from 'chai';
+import { runSingletonManagerClassSuite } from '../test-suites/runSingletonManagerClassSuite.suite.js';
+
+runSingletonManagerClassSuite({ expect });
diff --git a/packages/singleton-manager/test-suites/runSingletonManagerClassSuite.suite.js b/packages/singleton-manager/test-suites/runSingletonManagerClassSuite.suite.js
new file mode 100644
index 0000000000..c775576a43
--- /dev/null
+++ b/packages/singleton-manager/test-suites/runSingletonManagerClassSuite.suite.js
@@ -0,0 +1,39 @@
+import { SingletonManagerClass } from 'singleton-manager';
+
+/**
+ * @param {{expect: function}} config
+ */
+export function runSingletonManagerClassSuite({ expect }) {
+  describe('SingletonManagerClass', () => {
+    it('returns undefined and has false if not set', async () => {
+      const mngr = new SingletonManagerClass();
+      expect(mngr.get('overlays/overlays.js::0.13.x')).to.be.undefined;
+      expect(mngr.has('overlays/overlays.js::0.13.x')).to.be.false;
+    });
+
+    it('return value and has true if set', () => {
+      const mngr = new SingletonManagerClass();
+      mngr.set('overlays/overlays.js::0.13.x', 'is-set');
+      expect(mngr.get('overlays/overlays.js::0.13.x')).to.equal('is-set');
+      expect(mngr.has('overlays/overlays.js::0.13.x')).to.be.true;
+      // make sure non set values are still correct
+      expect(mngr.get('overlays/overlays.js::0.14.x')).to.be.undefined;
+      expect(mngr.has('overlays/overlays.js::0.14.x')).to.be.false;
+    });
+
+    it('does not override existing keys (e.g. subsequential calls for the same keys are ignored)', () => {
+      const mngr = new SingletonManagerClass();
+      mngr.set('overlays/overlays.js::0.14.x', 'is-set');
+      mngr.set('overlays/overlays.js::0.14.x', 'new-set');
+      expect(mngr.get('overlays/overlays.js::0.14.x')).to.equal('is-set');
+    });
+
+    it('should return the same value with two SingletonManager instances', () => {
+      const mngr1 = new SingletonManagerClass();
+      const mngr2 = new SingletonManagerClass();
+
+      mngr1.set('overlays/overlays.js::0.15.x', 'is-set');
+      expect(mngr2.get('overlays/overlays.js::0.15.x')).to.equal('is-set');
+    });
+  });
+}
diff --git a/packages/singleton-manager/test/SingletonManagerClass.test.js b/packages/singleton-manager/test/SingletonManagerClass.test.js
index c2ca1b4ad0..46cae2ff25 100644
--- a/packages/singleton-manager/test/SingletonManagerClass.test.js
+++ b/packages/singleton-manager/test/SingletonManagerClass.test.js
@@ -1,36 +1,4 @@
 import { expect } from '@open-wc/testing';
+import { runSingletonManagerClassSuite } from '../test-suites/runSingletonManagerClassSuite.suite.js';
 
-import { SingletonManagerClass } from 'singleton-manager';
-
-describe('SingletonManagerClass', () => {
-  it('returns undefined and has false if not set', async () => {
-    const mngr = new SingletonManagerClass();
-    expect(mngr.get('overlays/overlays.js::0.13.x')).to.be.undefined;
-    expect(mngr.has('overlays/overlays.js::0.13.x')).to.be.false;
-  });
-
-  it('return value and has true if set', () => {
-    const mngr = new SingletonManagerClass();
-    mngr.set('overlays/overlays.js::0.13.x', 'is-set');
-    expect(mngr.get('overlays/overlays.js::0.13.x')).to.equal('is-set');
-    expect(mngr.has('overlays/overlays.js::0.13.x')).to.be.true;
-    // make sure non set values are still correct
-    expect(mngr.get('overlays/overlays.js::0.14.x')).to.be.undefined;
-    expect(mngr.has('overlays/overlays.js::0.14.x')).to.be.false;
-  });
-
-  it('does not override existing keys (e.g. subsequential calls for the same keys are ignored)', () => {
-    const mngr = new SingletonManagerClass();
-    mngr.set('overlays/overlays.js::0.14.x', 'is-set');
-    mngr.set('overlays/overlays.js::0.14.x', 'new-set');
-    expect(mngr.get('overlays/overlays.js::0.14.x')).to.equal('is-set');
-  });
-
-  it('should return the same value with two SingletonManager instances', () => {
-    const mngr1 = new SingletonManagerClass();
-    const mngr2 = new SingletonManagerClass();
-
-    mngr1.set('overlays/overlays.js::0.15.x', 'is-set');
-    expect(mngr2.get('overlays/overlays.js::0.15.x')).to.equal('is-set');
-  });
-});
+runSingletonManagerClassSuite({ expect });
diff --git a/packages/singleton-manager/tsconfig.json b/packages/singleton-manager/tsconfig.json
index e7787a4061..1e212b389b 100644
--- a/packages/singleton-manager/tsconfig.json
+++ b/packages/singleton-manager/tsconfig.json
@@ -2,8 +2,8 @@
   "extends": "../../tsconfig.json",
   "compilerOptions": {
     "outDir": "./dist-types",
-    "rootDir": ".",
+    "rootDir": "."
   },
-  "include": ["src", "test", "types"],
+  "include": ["src", "test", "test-node", "test-suites", "types"],
   "exclude": ["dist-types"]
 }