diff --git a/.eslintrc.json b/.eslintrc.json
index 70e114be..b370361f 100644
--- a/.eslintrc.json
+++ b/.eslintrc.json
@@ -34,7 +34,10 @@
         "plugin:promise/recommended",
         "plugin:react/recommended",
         "prettier"
-      ]
+      ],
+      "rules": {
+        "import/extensions": "error"
+      }
     },
     {
       "files": [
@@ -60,9 +63,13 @@
         "prettier"
       ],
       "rules": {
-        "import/namespace": ["error", {
-          "allowComputed": true
-        }],
+        "import/extensions": "error",
+        "import/namespace": [
+          "error",
+          {
+            "allowComputed": true
+          }
+        ],
         "jest/no-disabled-tests": "off",
         "no-useless-assign/no-useless-assign": "warn",
         "node/no-missing-import": "off",
diff --git a/src/backend/controllers/auth.js b/src/backend/controllers/auth.js
index 68b69960..48e0c61a 100644
--- a/src/backend/controllers/auth.js
+++ b/src/backend/controllers/auth.js
@@ -4,7 +4,7 @@ import router from 'koa-joi-router';
 import anonymus from 'anonymus';
 import merge from 'lodash.merge';
 import { getLogger } from '../log.ts';
-import { getOrcidPerson, getOrcidWorks, processWorks } from '../utils/orcid.js';
+import { getOrcidPerson, getOrcidWorks, processWorks } from '../utils/orcid';
 
 const log = getLogger('backend:controllers:auth');
 
diff --git a/src/backend/controllers/docs.js b/src/backend/controllers/docs.js
index 8ad1ed20..93ba6590 100644
--- a/src/backend/controllers/docs.js
+++ b/src/backend/controllers/docs.js
@@ -1,23 +1,23 @@
 import { koaSwagger } from 'koa2-swagger-ui';
 import { SwaggerAPI } from 'koa-joi-router-docs';
-import preprintRoutes from '../controllers/preprint.js';
+import preprintRoutes from '../controllers/preprint';
 import { getLogger } from '../log.ts';
 import router from 'koa-joi-router';
-import userRoutes from './user.js';
-import fullReviewRoutes from './fullReview.js';
-import commentRoutes from './comment.js';
-import badgeRoutes from './badge.js';
-import expertiseRoutes from './expertise.js';
-import communityRoutes from './community.js';
-import eventRoutes from './event.js';
-import groupRoutes from './group.js';
-import personaRoutes from './persona.js';
-import rapidReviewRoutes from './rapidReview.js';
-import reportRoutes from '../controllers/report.js';
-import requestRoutes from './request.js';
-import tagRoutes from './tag.js';
-import templateRoutes from './template.js';
-import notificationRoutes from '../controllers/notification.js';
+import userRoutes from './user';
+import fullReviewRoutes from './fullReview';
+import commentRoutes from './comment';
+import badgeRoutes from './badge';
+import expertiseRoutes from './expertise';
+import communityRoutes from './community';
+import eventRoutes from './event';
+import groupRoutes from './group';
+import personaRoutes from './persona';
+import rapidReviewRoutes from './rapidReview';
+import reportRoutes from '../controllers/report';
+import requestRoutes from './request';
+import tagRoutes from './tag';
+import templateRoutes from './template';
+import notificationRoutes from '../controllers/notification';
 
 const log = getLogger('apiDocs:::');
 
diff --git a/src/backend/controllers/group.js b/src/backend/controllers/group.js
index 50516778..54d73e2a 100644
--- a/src/backend/controllers/group.js
+++ b/src/backend/controllers/group.js
@@ -1,6 +1,6 @@
 import router from 'koa-joi-router';
 import { getLogger } from '../log.ts';
-import { getErrorMessages } from '../utils/errors.js';
+import { getErrorMessages } from '../utils/errors';
 
 const Joi = router.Joi;
 const log = getLogger('backend:controllers:group');
diff --git a/src/backend/scripts/genSpec.js b/src/backend/scripts/genSpec.js
index 300c2e37..22960aa2 100644
--- a/src/backend/scripts/genSpec.js
+++ b/src/backend/scripts/genSpec.js
@@ -1,21 +1,21 @@
 import { SwaggerAPI } from 'koa-joi-router-docs';
-import preprintRoutes from '../controllers/preprint.js';
-import authWrapper from '../middleware/auth.js';
-import userRoutes from '../controllers/user.js';
-import fullReviewRoutes from '../controllers/fullReview.js';
-import commentRoutes from '../controllers/comment.js';
-import badgeRoutes from '../controllers/badge.js';
-import expertiseRoutes from '../controllers/expertise.js';
-import communityRoutes from '../controllers/community.js';
-import eventRoutes from '../controllers/event.js';
-import groupRoutes from '../controllers/group.js';
-import personaRoutes from '../controllers/persona.js';
-import rapidReviewRoutes from '../controllers/rapidReview.js';
-import reportRoutes from '../controllers/report.js';
-import requestRoutes from '../controllers/request.js';
-import tagRoutes from '../controllers/tag.js';
-import templateRoutes from '../controllers/template.js';
-import notificationRoutes from '../controllers/notification.js';
+import preprintRoutes from '../controllers/preprint';
+import authWrapper from '../middleware/auth';
+import userRoutes from '../controllers/user';
+import fullReviewRoutes from '../controllers/fullReview';
+import commentRoutes from '../controllers/comment';
+import badgeRoutes from '../controllers/badge';
+import expertiseRoutes from '../controllers/expertise';
+import communityRoutes from '../controllers/community';
+import eventRoutes from '../controllers/event';
+import groupRoutes from '../controllers/group';
+import personaRoutes from '../controllers/persona';
+import rapidReviewRoutes from '../controllers/rapidReview';
+import reportRoutes from '../controllers/report';
+import requestRoutes from '../controllers/request';
+import tagRoutes from '../controllers/tag';
+import templateRoutes from '../controllers/template';
+import notificationRoutes from '../controllers/notification';
 
 function docs() {
   const generator = new SwaggerAPI();
diff --git a/src/backend/server.ts b/src/backend/server.ts
index c537368d..6d8b230f 100644
--- a/src/backend/server.ts
+++ b/src/backend/server.ts
@@ -28,7 +28,7 @@ import serialize from 'serialize-javascript';
 import { createError } from './utils/http-errors';
 
 // Our middlewares
-import authWrapper from './middleware/auth.js'; // authorization/user roles
+import authWrapper from './middleware/auth'; // authorization/user roles
 import currentCommunity from './middleware/community';
 import currentPersona from './middleware/persona';
 import currentUser from './middleware/user';
@@ -58,25 +58,25 @@ import {
 } from './models';
 
 // Our controllers
-import AuthController from './controllers/auth.js'; // authentication/logins
-import BadgeController from './controllers/badge.js';
-import CommentController from './controllers/comment.js';
-import CommunityController from './controllers/community.js';
-import ExpertiseController from './controllers/expertise.js';
-import FullReviewController from './controllers/fullReview.js';
-import DraftController from './controllers/fullReviewDraft.js';
-import GroupController from './controllers/group.js';
-import UserController from './controllers/user.js';
-import PersonaController from './controllers/persona.js';
-import PreprintController from './controllers/preprint.js';
-import RapidController from './controllers/rapidReview.js';
-import ReportController from './controllers/report.js';
-import RequestController from './controllers/request.js';
-import TagController from './controllers/tag.js';
-import TemplateController from './controllers/template.js';
-import DocsController from './controllers/docs.js';
-import EventController from './controllers/event.js';
-import NotificationController from './controllers/notification.js';
+import AuthController from './controllers/auth'; // authentication/logins
+import BadgeController from './controllers/badge';
+import CommentController from './controllers/comment';
+import CommunityController from './controllers/community';
+import ExpertiseController from './controllers/expertise';
+import FullReviewController from './controllers/fullReview';
+import DraftController from './controllers/fullReviewDraft';
+import GroupController from './controllers/group';
+import UserController from './controllers/user';
+import PersonaController from './controllers/persona';
+import PreprintController from './controllers/preprint';
+import RapidController from './controllers/rapidReview';
+import ReportController from './controllers/report';
+import RequestController from './controllers/request';
+import TagController from './controllers/tag';
+import TemplateController from './controllers/template';
+import DocsController from './controllers/docs';
+import EventController from './controllers/event';
+import NotificationController from './controllers/notification';
 
 /* eslint-disable @typescript-eslint/ban-ts-comment */
 
diff --git a/src/common/utils/index.ts b/src/common/utils/index.ts
index 54e2e6aa..dbc202af 100644
--- a/src/common/utils/index.ts
+++ b/src/common/utils/index.ts
@@ -1 +1 @@
-export * from './ids.js';
+export * from './ids';
diff --git a/src/frontend/components/Communities.js b/src/frontend/components/Communities.js
index 6f58d053..a15bc249 100644
--- a/src/frontend/components/Communities.js
+++ b/src/frontend/components/Communities.js
@@ -13,7 +13,7 @@ import { useGetCommunities, useGetTags } from '../hooks/api-hooks.tsx';
 import { processParams, searchParamsToObject } from '../utils/search';
 
 // components
-import CommunityCard from './CommunityCard.js';
+import CommunityCard from './CommunityCard';
 import HeaderBar from './header-bar';
 import Loading from './loading';
 import SearchBar from './search-bar';
diff --git a/src/frontend/components/Community.js b/src/frontend/components/Community.js
index bef0409a..c85381b6 100644
--- a/src/frontend/components/Community.js
+++ b/src/frontend/components/Community.js
@@ -6,7 +6,7 @@ import { Helmet } from 'react-helmet-async';
 import MuiSearchBar from 'material-ui-search-bar';
 import { useIntl } from 'react-intl';
 
-import { createPreprintId } from '../../common/utils/ids.js';
+import { createPreprintId } from '../../common/utils/ids';
 
 // contexts
 import UserProvider from '../contexts/user-context';
diff --git a/src/frontend/components/activity-card.js b/src/frontend/components/activity-card.js
index 83d736db..ab82eb1a 100644
--- a/src/frontend/components/activity-card.js
+++ b/src/frontend/components/activity-card.js
@@ -5,7 +5,7 @@ import PropTypes from 'prop-types';
 
 // utils
 import { getFormattedDatePosted } from '../utils/preprints';
-import { createPreprintId } from '../../common/utils/ids.js';
+import { createPreprintId } from '../../common/utils/ids';
 
 // hooks
 import { useGetPreprint } from '../hooks/api-hooks.tsx';
diff --git a/src/frontend/components/dashboard.js b/src/frontend/components/dashboard.js
index bc15a88a..e233d36f 100644
--- a/src/frontend/components/dashboard.js
+++ b/src/frontend/components/dashboard.js
@@ -5,7 +5,7 @@ import { subDays } from 'date-fns';
 import { useHistory, useLocation } from 'react-router-dom';
 
 // utils
-import { createPreprintId } from '../../common/utils/ids.js';
+import { createPreprintId } from '../../common/utils/ids';
 
 import { ORG } from '../constants';
 
diff --git a/src/frontend/components/preprint-card.js b/src/frontend/components/preprint-card.js
index d876d771..900f13f6 100644
--- a/src/frontend/components/preprint-card.js
+++ b/src/frontend/components/preprint-card.js
@@ -7,7 +7,7 @@ import { formatDistanceStrict } from 'date-fns';
 // utils
 import { getTags } from '../utils/stats';
 import { getFormattedDatePosted } from '../utils/preprints';
-import { createPreprintId, decodePreprintId } from '../../common/utils/ids.js';
+import { createPreprintId, decodePreprintId } from '../../common/utils/ids';
 
 // hooks
 import { useAnimatedScore } from '../hooks/score-hooks';
diff --git a/src/frontend/components/preprint-preview.js b/src/frontend/components/preprint-preview.js
index b4b2d9f4..c96e8230 100644
--- a/src/frontend/components/preprint-preview.js
+++ b/src/frontend/components/preprint-preview.js
@@ -5,7 +5,7 @@ import { useHistory } from 'react-router-dom';
 
 // utils
 import { getFormattedDatePosted } from '../utils/preprints';
-import { createPreprintId } from '../../common/utils/ids.js';
+import { createPreprintId } from '../../common/utils/ids';
 
 // Material UI components
 import { makeStyles } from '@material-ui/core/styles';
diff --git a/src/frontend/components/recent-activity.js b/src/frontend/components/recent-activity.js
index d386f1b8..1e75f7ef 100644
--- a/src/frontend/components/recent-activity.js
+++ b/src/frontend/components/recent-activity.js
@@ -4,7 +4,7 @@ import PropTypes from 'prop-types';
 
 //utils
 import { formatDistanceStrict } from 'date-fns';
-import { createPreprintId } from '../../common/utils/ids.js';
+import { createPreprintId } from '../../common/utils/ids';
 
 //material ui
 import Link from '@material-ui/core/Link';
diff --git a/src/frontend/components/reviews.js b/src/frontend/components/reviews.js
index 991e3911..058ae897 100644
--- a/src/frontend/components/reviews.js
+++ b/src/frontend/components/reviews.js
@@ -36,7 +36,7 @@ import {
 } from '../hooks/ui-hooks';
 
 // utils
-import { createPreprintId } from '../../common/utils/ids.js';
+import { createPreprintId } from '../../common/utils/ids';
 import { processParams, searchParamsToObject } from '../utils/search';
 
 // components
diff --git a/src/frontend/components/shell-content.js b/src/frontend/components/shell-content.js
index fa6f8f87..df70c601 100644
--- a/src/frontend/components/shell-content.js
+++ b/src/frontend/components/shell-content.js
@@ -8,7 +8,7 @@ import { useLocation } from 'react-router-dom';
 import { usePostRequests } from '../hooks/api-hooks.tsx';
 
 // utils
-import { createPreprintId } from '../../common/utils/ids.js';
+import { createPreprintId } from '../../common/utils/ids';
 
 // Material UI imports
 import { makeStyles } from '@material-ui/core/styles';