diff --git a/packages/database/CHANGELOG.md b/packages/database/CHANGELOG.md
index d2d6d5b62a0..19219c0d2db 100644
--- a/packages/database/CHANGELOG.md
+++ b/packages/database/CHANGELOG.md
@@ -1,6 +1,7 @@
 # Unreleased
 - [feature] Added ServerValue.increment() to support atomic field value increments
   without transactions.
+- [fixed] Fixed Realtime Database URL parsing bug to support domains with more than 3 components.
 
 # Released
 - [fixed] Fixed an issue that caused large numeric values with leading zeros to
diff --git a/packages/database/src/core/util/libs/parser.ts b/packages/database/src/core/util/libs/parser.ts
index bb789c08fb7..0ef62fd11ba 100644
--- a/packages/database/src/core/util/libs/parser.ts
+++ b/packages/database/src/core/util/libs/parser.ts
@@ -1,6 +1,6 @@
 /**
  * @license
- * Copyright 2017 Google Inc.
+ * Copyright 2017 Google LLC
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -72,7 +72,7 @@ export const parseRepoInfo = function(
   const parsedUrl = parseDatabaseURL(dataURL),
     namespace = parsedUrl.namespace;
 
-  if (parsedUrl.domain === 'firebase') {
+  if (parsedUrl.domain === 'firebase.com') {
     fatal(
       parsedUrl.host +
         ' is no longer supported. ' +
@@ -171,20 +171,21 @@ export const parseDatabaseURL = function(
       secure = scheme === 'https' || scheme === 'wss';
       port = parseInt(host.substring(colonInd + 1), 10);
     } else {
-      colonInd = dataURL.length;
+      colonInd = host.length;
     }
 
-    const parts = host.split('.');
-    if (parts.length === 3) {
+    const hostWithoutPort = host.slice(0, colonInd);
+    if (hostWithoutPort.toLowerCase() === 'localhost') {
+      domain = 'localhost';
+    } else if (hostWithoutPort.split('.').length <= 2) {
+      domain = hostWithoutPort;
+    } else {
+      // Interpret the subdomain of a 3 or more component URL as the namespace name.
+      const dotInd = host.indexOf('.');
+      subdomain = host.substring(0, dotInd).toLowerCase();
+      domain = host.substring(dotInd + 1);
       // Normalize namespaces to lowercase to share storage / connection.
-      domain = parts[1];
-      subdomain = parts[0].toLowerCase();
-      // We interpret the subdomain of a 3 component URL as the namespace name.
       namespace = subdomain;
-    } else if (parts.length === 2) {
-      domain = parts[0];
-    } else if (parts[0].slice(0, colonInd).toLowerCase() === 'localhost') {
-      domain = 'localhost';
     }
     // Always treat the value of the `ns` as the namespace name if it is present.
     if ('ns' in queryParams) {
diff --git a/packages/database/test/database.test.ts b/packages/database/test/database.test.ts
index 0cc9f6c9d83..1187032eb32 100644
--- a/packages/database/test/database.test.ts
+++ b/packages/database/test/database.test.ts
@@ -1,6 +1,6 @@
 /**
  * @license
- * Copyright 2017 Google Inc.
+ * Copyright 2017 Google LLC
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -62,18 +62,49 @@ describe('Database Tests', () => {
     expect(db.ref().toString()).to.equal('https://foo.bar.com/');
   });
 
+  it('Can get database with multi-region URL', () => {
+    const db = defaultApp.database('http://foo.euw1.firebasedatabase.app');
+    expect(db).to.be.ok;
+    expect(db.repo_.repoInfo_.namespace).to.equal('foo');
+    expect(db.ref().toString()).to.equal(
+      'https://foo.euw1.firebasedatabase.app/'
+    );
+  });
+
+  it('Can get database with upper case URL', () => {
+    const db = defaultApp.database('http://fOO.EUW1.firebaseDATABASE.app');
+    expect(db).to.be.ok;
+    expect(db.repo_.repoInfo_.namespace).to.equal('foo');
+    expect(db.ref().toString()).to.equal(
+      'https://foo.euw1.firebasedatabase.app/'
+    );
+  });
+
+  it('Can get database with localhost URL', () => {
+    const db = defaultApp.database('http://localhost');
+    expect(db).to.be.ok;
+    expect(db.ref().toString()).to.equal('https://localhost/');
+  });
+
   it('Can get database with localhost URL and port', () => {
     const db = defaultApp.database('http://localhost:80');
     expect(db).to.be.ok;
     expect(db.ref().toString()).to.equal('http://localhost:80/');
   });
 
-  it('Can get database with localhost URL', () => {
-    const db = defaultApp.database('http://localhost');
+  it('Can get database with a upper case localhost URL', () => {
+    const db = defaultApp.database('http://LOCALHOST');
     expect(db).to.be.ok;
     expect(db.ref().toString()).to.equal('https://localhost/');
   });
 
+  it('Can get database with a upper case localhost URL and ns', () => {
+    const db = defaultApp.database('http://LOCALHOST?ns=foo');
+    expect(db).to.be.ok;
+    expect(db.repo_.repoInfo_.namespace).to.equal('foo');
+    expect(db.ref().toString()).to.equal('https://localhost/');
+  });
+
   it('Can read ns query param', () => {
     const db = defaultApp.database('http://localhost:80/?ns=foo&unused=true');
     expect(db).to.be.ok;
@@ -111,10 +142,19 @@ describe('Database Tests', () => {
     }).to.throw(/Database initialized multiple times/i);
   });
 
+  it('Databases with legacy domain', () => {
+    expect(() => {
+      defaultApp.database('http://foo.firebase.com/');
+    }).to.throw(/is no longer supported/i);
+  });
+
   it('Databases with invalid custom URLs', () => {
     expect(() => {
       defaultApp.database('not-a-url');
     }).to.throw(/Cannot parse Firebase url/i);
+    expect(() => {
+      defaultApp.database('http://foo.com');
+    }).to.throw(/Cannot parse Firebase url/i);
     expect(() => {
       defaultApp.database('http://fblocal.com');
     }).to.throw(/Cannot parse Firebase url/i);