diff --git a/.gitignore b/.gitignore
index 3c34f29ac..03c14b3cf 100644
--- a/.gitignore
+++ b/.gitignore
@@ -10,3 +10,4 @@ build/
 *.tsbuildinfo
 .cache
 .watchmanconfig
+coverage
diff --git a/babel.config.js b/babel.config.js
index d590727a4..c5246556b 100644
--- a/babel.config.js
+++ b/babel.config.js
@@ -28,4 +28,5 @@ module.exports = {
       }),
     ],
   ],
+  sourceMaps: true,
 };
diff --git a/jest.config.js b/jest.config.js
index 00f379057..09aa62018 100644
--- a/jest.config.js
+++ b/jest.config.js
@@ -15,4 +15,10 @@ module.exports = {
       testMatch: ['<rootDir>/**/__tests__/*{.,-}test.[jt]s'],
     },
   ],
+  collectCoverageFrom: [
+    '**/packages/*/**/*.ts',
+    '!**/__mocks__/**',
+    '!**/__tests__/**',
+    '!**/build/**',
+  ],
 };
diff --git a/packages/cli-types/package.json b/packages/cli-types/package.json
index d128a06f9..932812119 100644
--- a/packages/cli-types/package.json
+++ b/packages/cli-types/package.json
@@ -5,6 +5,10 @@
   "publishConfig": {
     "access": "public"
   },
+  "files": [
+    "build",
+    "!build/**/*.map"
+  ],
   "types": "build/index.d.ts",
   "license": "MIT"
 }
diff --git a/packages/cli/package.json b/packages/cli/package.json
index 544b70616..faad4fe51 100644
--- a/packages/cli/package.json
+++ b/packages/cli/package.json
@@ -12,6 +12,7 @@
   },
   "files": [
     "build",
+    "!build/**/*.map",
     "setup_env.sh"
   ],
   "engineStrict": true,
diff --git a/packages/debugger-ui/package.json b/packages/debugger-ui/package.json
index 48723372c..8fc44421e 100644
--- a/packages/debugger-ui/package.json
+++ b/packages/debugger-ui/package.json
@@ -9,7 +9,8 @@
     "build:middleware": "tsc"
   },
   "files": [
-    "build"
+    "build",
+    "!build/**/*.map"
   ],
   "devDependencies": {
     "@babel/core": "^7.6.4",
diff --git a/packages/platform-android/package.json b/packages/platform-android/package.json
index bd49ba609..c9874a336 100644
--- a/packages/platform-android/package.json
+++ b/packages/platform-android/package.json
@@ -17,6 +17,7 @@
   },
   "files": [
     "build",
+    "!build/**/*.map",
     "native_modules.gradle"
   ],
   "devDependencies": {
diff --git a/packages/platform-ios/package.json b/packages/platform-ios/package.json
index 8cbb0e66d..b73aa0f87 100644
--- a/packages/platform-ios/package.json
+++ b/packages/platform-ios/package.json
@@ -19,6 +19,7 @@
   },
   "files": [
     "build",
+    "!build/**/*.map",
     "native_modules.rb"
   ]
 }
diff --git a/packages/tools/package.json b/packages/tools/package.json
index 382487f03..e99ac14eb 100644
--- a/packages/tools/package.json
+++ b/packages/tools/package.json
@@ -18,6 +18,7 @@
     "@types/node-fetch": "^2.3.3"
   },
   "files": [
-    "build"
+    "build",
+    "!build/**/*.map"
   ]
 }
diff --git a/scripts/build.js b/scripts/build.js
index b0c10568d..fc2f39d5a 100644
--- a/scripts/build.js
+++ b/scripts/build.js
@@ -93,9 +93,17 @@ function buildFile(file, silent) {
       );
   } else {
     const options = Object.assign({}, transformOptions);
-    const transformed = babel.transformFileSync(file, options).code;
+    const filename = path.basename(destPath);
 
-    fs.writeFileSync(destPath, transformed);
+    let {code, map} = babel.transformFileSync(file, options);
+
+    if (!file.endsWith('.d.ts') && map.sources.length > 0) {
+      code = `${code}\n\n//# sourceMappingURL=${filename}.map`;
+      map.sources = [path.relative(path.dirname(destPath), file)];
+      fs.writeFileSync(`${destPath}.map`, JSON.stringify(map));
+    }
+
+    fs.writeFileSync(destPath, code);
 
     silent ||
       process.stdout.write(