diff --git a/.eslintignore b/.eslintignore
index 1e9949e11e9..71952f23547 100644
--- a/.eslintignore
+++ b/.eslintignore
@@ -80,6 +80,60 @@ packages/app-cli/tests/HtmlToMd.js.map
 packages/app-cli/tests/MdToHtml.d.ts
 packages/app-cli/tests/MdToHtml.js
 packages/app-cli/tests/MdToHtml.js.map
+packages/app-cli/tests/Synchronizer.basics.d.ts
+packages/app-cli/tests/Synchronizer.basics.js
+packages/app-cli/tests/Synchronizer.basics.js.map
+packages/app-cli/tests/Synchronizer.conflicts.d.ts
+packages/app-cli/tests/Synchronizer.conflicts.js
+packages/app-cli/tests/Synchronizer.conflicts.js.map
+packages/app-cli/tests/Synchronizer.e2ee.d.ts
+packages/app-cli/tests/Synchronizer.e2ee.js
+packages/app-cli/tests/Synchronizer.e2ee.js.map
+packages/app-cli/tests/Synchronizer.resources.d.ts
+packages/app-cli/tests/Synchronizer.resources.js
+packages/app-cli/tests/Synchronizer.resources.js.map
+packages/app-cli/tests/Synchronizer.revisions.d.ts
+packages/app-cli/tests/Synchronizer.revisions.js
+packages/app-cli/tests/Synchronizer.revisions.js.map
+packages/app-cli/tests/Synchronizer.sharing.d.ts
+packages/app-cli/tests/Synchronizer.sharing.js
+packages/app-cli/tests/Synchronizer.sharing.js.map
+packages/app-cli/tests/Synchronizer.tags.d.ts
+packages/app-cli/tests/Synchronizer.tags.js
+packages/app-cli/tests/Synchronizer.tags.js.map
+packages/app-cli/tests/Synchronizer.tools.d.ts
+packages/app-cli/tests/Synchronizer.tools.js
+packages/app-cli/tests/Synchronizer.tools.js.map
+packages/app-cli/tests/dateTimeFormats.d.ts
+packages/app-cli/tests/dateTimeFormats.js
+packages/app-cli/tests/dateTimeFormats.js.map
+packages/app-cli/tests/file-api-driver.d.ts
+packages/app-cli/tests/file-api-driver.js
+packages/app-cli/tests/file-api-driver.js.map
+packages/app-cli/tests/fsDriver.d.ts
+packages/app-cli/tests/fsDriver.js
+packages/app-cli/tests/fsDriver.js.map
+packages/app-cli/tests/htmlUtils.d.ts
+packages/app-cli/tests/htmlUtils.js
+packages/app-cli/tests/htmlUtils.js.map
+packages/app-cli/tests/models_Folder.d.ts
+packages/app-cli/tests/models_Folder.js
+packages/app-cli/tests/models_Folder.js.map
+packages/app-cli/tests/models_Folder.sharing.d.ts
+packages/app-cli/tests/models_Folder.sharing.js
+packages/app-cli/tests/models_Folder.sharing.js.map
+packages/app-cli/tests/models_Note.d.ts
+packages/app-cli/tests/models_Note.js
+packages/app-cli/tests/models_Note.js.map
+packages/app-cli/tests/models_Setting.d.ts
+packages/app-cli/tests/models_Setting.js
+packages/app-cli/tests/models_Setting.js.map
+packages/app-cli/tests/models_Tag.d.ts
+packages/app-cli/tests/models_Tag.js
+packages/app-cli/tests/models_Tag.js.map
+packages/app-cli/tests/registry.d.ts
+packages/app-cli/tests/registry.js
+packages/app-cli/tests/registry.js.map
 packages/app-cli/tests/MdToMd.d.ts
 packages/app-cli/tests/MdToMd.js
 packages/app-cli/tests/MdToMd.js.map
diff --git a/.gitignore b/.gitignore
index d070efdeeec..ac8159aa1e9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -66,6 +66,60 @@ packages/app-cli/tests/HtmlToMd.js.map
 packages/app-cli/tests/MdToHtml.d.ts
 packages/app-cli/tests/MdToHtml.js
 packages/app-cli/tests/MdToHtml.js.map
+packages/app-cli/tests/Synchronizer.basics.d.ts
+packages/app-cli/tests/Synchronizer.basics.js
+packages/app-cli/tests/Synchronizer.basics.js.map
+packages/app-cli/tests/Synchronizer.conflicts.d.ts
+packages/app-cli/tests/Synchronizer.conflicts.js
+packages/app-cli/tests/Synchronizer.conflicts.js.map
+packages/app-cli/tests/Synchronizer.e2ee.d.ts
+packages/app-cli/tests/Synchronizer.e2ee.js
+packages/app-cli/tests/Synchronizer.e2ee.js.map
+packages/app-cli/tests/Synchronizer.resources.d.ts
+packages/app-cli/tests/Synchronizer.resources.js
+packages/app-cli/tests/Synchronizer.resources.js.map
+packages/app-cli/tests/Synchronizer.revisions.d.ts
+packages/app-cli/tests/Synchronizer.revisions.js
+packages/app-cli/tests/Synchronizer.revisions.js.map
+packages/app-cli/tests/Synchronizer.sharing.d.ts
+packages/app-cli/tests/Synchronizer.sharing.js
+packages/app-cli/tests/Synchronizer.sharing.js.map
+packages/app-cli/tests/Synchronizer.tags.d.ts
+packages/app-cli/tests/Synchronizer.tags.js
+packages/app-cli/tests/Synchronizer.tags.js.map
+packages/app-cli/tests/Synchronizer.tools.d.ts
+packages/app-cli/tests/Synchronizer.tools.js
+packages/app-cli/tests/Synchronizer.tools.js.map
+packages/app-cli/tests/dateTimeFormats.d.ts
+packages/app-cli/tests/dateTimeFormats.js
+packages/app-cli/tests/dateTimeFormats.js.map
+packages/app-cli/tests/file-api-driver.d.ts
+packages/app-cli/tests/file-api-driver.js
+packages/app-cli/tests/file-api-driver.js.map
+packages/app-cli/tests/fsDriver.d.ts
+packages/app-cli/tests/fsDriver.js
+packages/app-cli/tests/fsDriver.js.map
+packages/app-cli/tests/htmlUtils.d.ts
+packages/app-cli/tests/htmlUtils.js
+packages/app-cli/tests/htmlUtils.js.map
+packages/app-cli/tests/models_Folder.d.ts
+packages/app-cli/tests/models_Folder.js
+packages/app-cli/tests/models_Folder.js.map
+packages/app-cli/tests/models_Folder.sharing.d.ts
+packages/app-cli/tests/models_Folder.sharing.js
+packages/app-cli/tests/models_Folder.sharing.js.map
+packages/app-cli/tests/models_Note.d.ts
+packages/app-cli/tests/models_Note.js
+packages/app-cli/tests/models_Note.js.map
+packages/app-cli/tests/models_Setting.d.ts
+packages/app-cli/tests/models_Setting.js
+packages/app-cli/tests/models_Setting.js.map
+packages/app-cli/tests/models_Tag.d.ts
+packages/app-cli/tests/models_Tag.js
+packages/app-cli/tests/models_Tag.js.map
+packages/app-cli/tests/registry.d.ts
+packages/app-cli/tests/registry.js
+packages/app-cli/tests/registry.js.map
 packages/app-cli/tests/MdToMd.d.ts
 packages/app-cli/tests/MdToMd.js
 packages/app-cli/tests/MdToMd.js.map
diff --git a/packages/app-cli/tests/models_Tag.ts b/packages/app-cli/tests/models_Tag.ts
new file mode 100644
index 00000000000..dec24c35960
--- /dev/null
+++ b/packages/app-cli/tests/models_Tag.ts
@@ -0,0 +1,159 @@
+import { setupDatabaseAndSynchronizer, switchClient, checkThrowAsync } from './test-utils.js';
+import Folder from '@joplin/lib/models/Folder';
+import Note from '@joplin/lib/models/Note';
+import Tag from '@joplin/lib/models/Tag';
+
+describe('models_Tag', function() {
+
+	beforeEach(async (done) => {
+		await setupDatabaseAndSynchronizer(1);
+		await switchClient(1);
+		done();
+	});
+
+	it('should add tags by title', (async () => {
+		const folder1 = await Folder.save({ title: 'folder1' });
+		const note1 = await Note.save({ title: 'ma note', parent_id: folder1.id });
+
+		await Tag.setNoteTagsByTitles(note1.id, ['un', 'deux']);
+
+		const noteTags = await Tag.tagsByNoteId(note1.id);
+		expect(noteTags.length).toBe(2);
+	}));
+
+	it('should not allow renaming tag to existing tag names', (async () => {
+		const folder1 = await Folder.save({ title: 'folder1' });
+		const note1 = await Note.save({ title: 'ma note', parent_id: folder1.id });
+
+		await Tag.setNoteTagsByTitles(note1.id, ['un', 'deux']);
+
+		const tagUn = await Tag.loadByTitle('un');
+		const hasThrown = await checkThrowAsync(async () => await Tag.save({ id: tagUn.id, title: 'deux' }, { userSideValidation: true }));
+
+		expect(hasThrown).toBe(true);
+	}));
+
+	it('should not return tags without notes', (async () => {
+		const folder1 = await Folder.save({ title: 'folder1' });
+		const note1 = await Note.save({ title: 'ma note', parent_id: folder1.id });
+		await Tag.setNoteTagsByTitles(note1.id, ['un']);
+
+		let tags = await Tag.allWithNotes();
+		expect(tags.length).toBe(1);
+
+		await Note.delete(note1.id);
+
+		tags = await Tag.allWithNotes();
+		expect(tags.length).toBe(0);
+	}));
+
+	it('should return tags with note counts', (async () => {
+		const folder1 = await Folder.save({ title: 'folder1' });
+		const note1 = await Note.save({ title: 'ma note', parent_id: folder1.id });
+		const note2 = await Note.save({ title: 'ma 2nd note', parent_id: folder1.id });
+		const todo1 = await Note.save({ title: 'todo 1', parent_id: folder1.id, is_todo: 1, todo_completed: 1590085027710 });
+		await Tag.setNoteTagsByTitles(note1.id, ['un']);
+		await Tag.setNoteTagsByTitles(note2.id, ['un']);
+		await Tag.setNoteTagsByTitles(todo1.id, ['un']);
+
+		let tags = await Tag.allWithNotes();
+		expect(tags.length).toBe(1);
+		expect(tags[0].note_count).toBe(3);
+		expect(tags[0].todo_completed_count).toBe(1);
+
+		await Note.delete(todo1.id);
+
+		tags = await Tag.allWithNotes();
+		expect(tags.length).toBe(1);
+		expect(tags[0].note_count).toBe(2);
+
+		await Note.delete(note1.id);
+
+		tags = await Tag.allWithNotes();
+		expect(tags.length).toBe(1);
+		expect(tags[0].note_count).toBe(1);
+
+		await Note.delete(note2.id);
+
+		tags = await Tag.allWithNotes();
+		expect(tags.length).toBe(0);
+	}));
+
+	it('should load individual tags with note count', (async () => {
+		const folder1 = await Folder.save({ title: 'folder1' });
+		const note1 = await Note.save({ title: 'ma note', parent_id: folder1.id });
+		const note2 = await Note.save({ title: 'ma 2nd note', parent_id: folder1.id });
+		const todo1 = await Note.save({ title: 'todo 2', parent_id: folder1.id, is_todo: 1, todo_completed: 1590085027710 });
+		const todo2 = await Note.save({ title: 'todo 2', parent_id: folder1.id, is_todo: 1 });
+		const tag = await Tag.save({ title: 'mytag' });
+		await Tag.addNote(tag.id, note1.id);
+
+		let tagWithCount = await Tag.loadWithCount(tag.id);
+		expect(tagWithCount.note_count).toBe(1);
+
+		await Tag.addNote(tag.id, note2.id);
+		tagWithCount = await Tag.loadWithCount(tag.id);
+		expect(tagWithCount.note_count).toBe(2);
+
+		await Tag.addNote(tag.id, todo1.id);
+		await Tag.addNote(tag.id, todo2.id);
+		tagWithCount = await Tag.loadWithCount(tag.id);
+		expect(tagWithCount.note_count).toBe(4);
+		expect(tagWithCount.todo_completed_count).toBe(1);
+	}));
+
+	it('should get common tags for set of notes', (async () => {
+		const folder1 = await Folder.save({ title: 'folder1' });
+		const taga = await Tag.save({ title: 'mytaga' });
+		const tagb = await Tag.save({ title: 'mytagb' });
+		const tagc = await Tag.save({ title: 'mytagc' });
+		await Tag.save({ title: 'mytagd' });
+
+		const note0 = await Note.save({ title: 'ma note 0', parent_id: folder1.id });
+		const note1 = await Note.save({ title: 'ma note 1', parent_id: folder1.id });
+		const note2 = await Note.save({ title: 'ma note 2', parent_id: folder1.id });
+		const note3 = await Note.save({ title: 'ma note 3', parent_id: folder1.id });
+
+		await Tag.addNote(taga.id, note1.id);
+
+		await Tag.addNote(taga.id, note2.id);
+		await Tag.addNote(tagb.id, note2.id);
+
+		await Tag.addNote(taga.id, note3.id);
+		await Tag.addNote(tagb.id, note3.id);
+		await Tag.addNote(tagc.id, note3.id);
+
+		let commonTags = await Tag.commonTagsByNoteIds(null);
+		expect(commonTags.length).toBe(0);
+
+		commonTags = await Tag.commonTagsByNoteIds(undefined);
+		expect(commonTags.length).toBe(0);
+
+		commonTags = await Tag.commonTagsByNoteIds([]);
+		expect(commonTags.length).toBe(0);
+
+		commonTags = await Tag.commonTagsByNoteIds([note0.id, note1.id, note2.id, note3.id]);
+		let commonTagIds = commonTags.map(t => t.id);
+		expect(commonTagIds.length).toBe(0);
+
+		commonTags = await Tag.commonTagsByNoteIds([note1.id, note2.id, note3.id]);
+		commonTagIds = commonTags.map(t => t.id);
+		expect(commonTagIds.length).toBe(1);
+		expect(commonTagIds.includes(taga.id)).toBe(true);
+
+		commonTags = await Tag.commonTagsByNoteIds([note2.id, note3.id]);
+		commonTagIds = commonTags.map(t => t.id);
+		expect(commonTagIds.length).toBe(2);
+		expect(commonTagIds.includes(taga.id)).toBe(true);
+		expect(commonTagIds.includes(tagb.id)).toBe(true);
+
+		commonTags = await Tag.commonTagsByNoteIds([note3.id]);
+
+		commonTagIds = commonTags.map(t => t.id);
+		expect(commonTags.length).toBe(3);
+		expect(commonTagIds.includes(taga.id)).toBe(true);
+		expect(commonTagIds.includes(tagb.id)).toBe(true);
+		expect(commonTagIds.includes(tagc.id)).toBe(true);
+	}));
+
+});
diff --git a/packages/app-desktop/gui/Sidebar/Sidebar.tsx b/packages/app-desktop/gui/Sidebar/Sidebar.tsx
index 474efcd7606..5b5eee00e9b 100644
--- a/packages/app-desktop/gui/Sidebar/Sidebar.tsx
+++ b/packages/app-desktop/gui/Sidebar/Sidebar.tsx
@@ -449,7 +449,11 @@ class SidebarComponent extends React.Component<Props, State> {
 
 	renderTag(tag: any, selected: boolean) {
 		const anchorRef = this.anchorItemRef('tag', tag.id);
-		const noteCount = Setting.value('showNoteCounts') ? this.renderNoteCount(tag.note_count) : '';
+		let noteCount = null;
+		if (Setting.value('showNoteCounts')) {
+			if (Setting.value('showCompletedTodos')) noteCount = this.renderNoteCount(tag.note_count);
+			else noteCount = this.renderNoteCount(tag.note_count - tag.todo_completed_count);
+		}
 
 		return (
 			<StyledListItem selected={selected}
diff --git a/packages/lib/JoplinDatabase.ts b/packages/lib/JoplinDatabase.ts
index 49b17551598..b0ff9c08a18 100644
--- a/packages/lib/JoplinDatabase.ts
+++ b/packages/lib/JoplinDatabase.ts
@@ -343,7 +343,7 @@ export default class JoplinDatabase extends Database {
 		// must be set in the synchronizer too.
 
 		// Note: v16 and v17 don't do anything. They were used to debug an issue.
-		const existingDatabaseVersions = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37];
+		const existingDatabaseVersions = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38];
 
 		let currentVersionIndex = existingDatabaseVersions.indexOf(fromVersion);
 
@@ -876,6 +876,18 @@ export default class JoplinDatabase extends Database {
 				queries.push('ALTER TABLE resources ADD COLUMN share_id TEXT NOT NULL DEFAULT ""');
 			}
 
+			if (targetVersion == 38) {
+				queries.push('DROP VIEW tags_with_note_count');
+				queries.push(`CREATE VIEW tags_with_note_count AS 
+						SELECT tags.id as id, tags.title as title, tags.created_time as created_time, tags.updated_time as updated_time, COUNT(notes.id) as note_count, 
+							SUM(CASE WHEN notes.todo_completed > 0 THEN 1 ELSE 0 END) AS todo_completed_count
+						FROM tags 
+							LEFT JOIN note_tags nt on nt.tag_id = tags.id 
+							LEFT JOIN notes on notes.id = nt.note_id 
+						WHERE notes.id IS NOT NULL 
+						GROUP BY tags.id`);
+			}
+
 			const updateVersionQuery = { sql: 'UPDATE version SET version = ?', params: [targetVersion] };
 
 			queries.push(updateVersionQuery);