diff --git a/build/azure-pipelines/mixin.js b/build/azure-pipelines/mixin.ts
similarity index 72%
rename from build/azure-pipelines/mixin.js
rename to build/azure-pipelines/mixin.ts
index e133b2d2bb9..b6818d6957d 100644
--- a/build/azure-pipelines/mixin.js
+++ b/build/azure-pipelines/mixin.ts
@@ -5,15 +5,33 @@
 
 'use strict';
 
-const json = require('gulp-json-editor');
+import * as json from 'gulp-json-editor';
 const buffer = require('gulp-buffer');
-const filter = require('gulp-filter');
-const es = require('event-stream');
-const vfs = require('vinyl-fs');
-const fancyLog = require('fancy-log');
-const ansiColors = require('ansi-colors');
-const fs = require('fs');
-const path = require('path');
+import * as filter from 'gulp-filter';
+import * as es from 'event-stream';
+import * as Vinyl from 'vinyl';
+import * as vfs from 'vinyl-fs';
+import * as fancyLog from 'fancy-log';
+import * as ansiColors from 'ansi-colors';
+import * as fs from 'fs';
+import * as path from 'path';
+
+interface IBuiltInExtension {
+	readonly name: string;
+	readonly version: string;
+	readonly repo: string;
+	readonly metadata: any;
+}
+
+interface OSSProduct {
+	readonly builtInExtensions: IBuiltInExtension[];
+	readonly webBuiltInExtensions?: IBuiltInExtension[];
+}
+
+interface Product {
+	readonly builtInExtensions?: IBuiltInExtension[] | { 'include'?: IBuiltInExtension[], 'exclude'?: string[] };
+	readonly webBuiltInExtensions?: IBuiltInExtension[];
+}
 
 function main() {
 	const quality = process.env['VSCODE_QUALITY'];
@@ -31,8 +49,8 @@ function main() {
 		.pipe(filter(f => !f.isDirectory()))
 		.pipe(productJsonFilter)
 		.pipe(buffer())
-		.pipe(json(o => {
-			const ossProduct = JSON.parse(fs.readFileSync(path.join(__dirname, '..', '..', 'product.json'), 'utf8'));
+		.pipe(json((o: Product) => {
+			const ossProduct = JSON.parse(fs.readFileSync(path.join(__dirname, '..', '..', 'product.json'), 'utf8')) as OSSProduct;
 			let builtInExtensions = ossProduct.builtInExtensions;
 
 			if (Array.isArray(o.builtInExtensions)) {
@@ -58,7 +76,7 @@ function main() {
 			return { webBuiltInExtensions: ossProduct.webBuiltInExtensions, ...o, builtInExtensions };
 		}))
 		.pipe(productJsonFilter.restore)
-		.pipe(es.mapSync(function (f) {
+		.pipe(es.mapSync(function (f: Vinyl) {
 			fancyLog(ansiColors.blue('[mixin]'), f.relative, ansiColors.green('✔︎'));
 			return f;
 		}))
diff --git a/build/azure-pipelines/upload-sourcemaps.js b/build/azure-pipelines/upload-sourcemaps.ts
similarity index 76%
rename from build/azure-pipelines/upload-sourcemaps.js
rename to build/azure-pipelines/upload-sourcemaps.ts
index b70335efe5b..11204f21c8e 100644
--- a/build/azure-pipelines/upload-sourcemaps.js
+++ b/build/azure-pipelines/upload-sourcemaps.ts
@@ -5,20 +5,22 @@
 
 'use strict';
 
-const path = require('path');
-const es = require('event-stream');
+import * as path from 'path';
+import * as es from 'event-stream';
+import * as Vinyl from 'vinyl';
+import * as vfs from 'vinyl-fs';
+import * as util from '../lib/util';
 const azure = require('gulp-azure-storage');
-const vfs = require('vinyl-fs');
-const util = require('../lib/util');
+
 const root = path.dirname(path.dirname(__dirname));
 const commit = util.getVersion(root);
 
 // optionally allow to pass in explicit base/maps to upload
 const [, , base, maps] = process.argv;
 
-const fetch = function (base, maps = `${base}/**/*.map`) {
+function src(base: string, maps = `${base}/**/*.map`) {
 	return vfs.src(maps, { base })
-		.pipe(es.mapSync(f => {
+		.pipe(es.mapSync((f: Vinyl) => {
 			f.path = `${f.base}/core/${f.relative}`;
 			return f;
 		}));
@@ -29,7 +31,7 @@ function main() {
 
 	// vscode client maps (default)
 	if (!base) {
-		const vs = fetch('out-vscode-min'); // client source-maps only
+		const vs = src('out-vscode-min'); // client source-maps only
 		sources.push(vs);
 
 		const extensionsOut = vfs.src(['.build/extensions/**/*.js.map', '!**/node_modules/**'], { base: '.build' });
@@ -38,11 +40,11 @@ function main() {
 
 	// specific client base/maps
 	else {
-		sources.push(fetch(base, maps));
+		sources.push(src(base, maps));
 	}
 
 	return es.merge(...sources)
-		.pipe(es.through(function (data) {
+		.pipe(es.through(function (data: Vinyl) {
 			console.log('Uploading Sourcemap', data.relative); // debug
 			this.emit('data', data);
 		}))