diff --git a/bootstrap/bootstrap_host.ts b/bootstrap/bootstrap_host.ts
index 9b5d265..1e91a68 100644
--- a/bootstrap/bootstrap_host.ts
+++ b/bootstrap/bootstrap_host.ts
@@ -1,9 +1,9 @@
 import * as bunyan from 'bunyan';
 import * as fs from 'fs';
-import Config from '../src/config';
-import Model from '../src/model/model';
+import Config from '../src/config.js';
+import Model from '../src/model/model.js';
 
-import { HARDWARE_LAB, LOUNGE, PRACTICE_SERVER, SOFTWARE_LAB } from './hosts_info';
+import { HARDWARE_LAB, LOUNGE, PRACTICE_SERVER, SOFTWARE_LAB } from './hosts_info.js';
 
 const config: Config = JSON.parse(fs.readFileSync('config.json', { encoding: 'utf-8' }));
 
diff --git a/bootstrap/rebuild_group_cache.ts b/bootstrap/rebuild_group_cache.ts
index 7b953d6..262af12 100644
--- a/bootstrap/rebuild_group_cache.ts
+++ b/bootstrap/rebuild_group_cache.ts
@@ -1,7 +1,7 @@
 import * as bunyan from 'bunyan';
 import * as fs from 'fs';
-import Config from '../src/config';
-import Model from '../src/model/model';
+import Config from '../src/config.js';
+import Model from '../src/model/model.js';
 
 const config: Config = JSON.parse(fs.readFileSync('config.json', { encoding: 'utf-8' }));
 
diff --git a/package.json b/package.json
index 04242ad..a2d998b 100644
--- a/package.json
+++ b/package.json
@@ -20,6 +20,7 @@
   "bugs": {
     "url": "https://github.com/bacchus-snu/id/issues"
   },
+  "type": "module",
   "dependencies": {
     "@koa/cors": "^5.0.0",
     "@phc/format": "^1.0.0",
diff --git a/src/api/email.ts b/src/api/email.ts
index 4309023..7dd6f7c 100644
--- a/src/api/email.ts
+++ b/src/api/email.ts
@@ -1,7 +1,7 @@
 import * as Bunyan from 'bunyan';
 import * as nodemailer from 'nodemailer';
-import Config from '../config';
-import { InvalidEmailError, ResendLimitExeededError } from '../model/errors';
+import Config from '../config.js';
+import { InvalidEmailError, ResendLimitExeededError } from '../model/errors.js';
 
 export interface EmailOption {
   address: string;
diff --git a/src/api/handlers/emails.ts b/src/api/handlers/emails.ts
index 4b8838c..7bb2e6e 100644
--- a/src/api/handlers/emails.ts
+++ b/src/api/handlers/emails.ts
@@ -1,11 +1,11 @@
 import { IMiddleware } from 'koa-router';
 import z from 'zod';
-import Config from '../../config';
-import { EmailAddress } from '../../model/email_addresses';
-import { EmailInUseError, InvalidEmailError, ResendLimitExeededError } from '../../model/errors';
-import Model from '../../model/model';
-import { sendEmail } from '../email';
-import emailVerificationTemplate from '../templates/verification_email_template';
+import Config from '../../config.js';
+import { EmailAddress } from '../../model/email_addresses.js';
+import { EmailInUseError, InvalidEmailError, ResendLimitExeededError } from '../../model/errors.js';
+import Model from '../../model/model.js';
+import { sendEmail } from '../email.js';
+import emailVerificationTemplate from '../templates/verification_email_template.js';
 
 export function sendVerificationEmail(model: Model, config: Config): IMiddleware {
   const bodySchema = z.object({
diff --git a/src/api/handlers/groups.ts b/src/api/handlers/groups.ts
index dbef10f..4453f14 100644
--- a/src/api/handlers/groups.ts
+++ b/src/api/handlers/groups.ts
@@ -1,8 +1,8 @@
 import { IMiddleware } from 'koa-router';
 import z from 'zod';
-import { BadParameterError } from '../../model/errors';
-import Model from '../../model/model';
-import { User } from '../../model/users';
+import { BadParameterError } from '../../model/errors.js';
+import Model from '../../model/model.js';
+import { User } from '../../model/users.js';
 
 export function listGroups(model: Model): IMiddleware {
   return async (ctx, next) => {
diff --git a/src/api/handlers/login.ts b/src/api/handlers/login.ts
index 74d00e6..ff93335 100644
--- a/src/api/handlers/login.ts
+++ b/src/api/handlers/login.ts
@@ -1,10 +1,10 @@
 import { IMiddleware } from 'koa-router';
 
 import z from 'zod';
-import Config from '../../config';
-import { AuthorizationError, ControllableError, NoSuchEntryError } from '../../model/errors';
-import Model from '../../model/model';
-import { SignatureError, verifyPubkeyReq } from '../pubkey';
+import Config from '../../config.js';
+import { AuthorizationError, ControllableError, NoSuchEntryError } from '../../model/errors.js';
+import Model from '../../model/model.js';
+import { SignatureError, verifyPubkeyReq } from '../pubkey.js';
 
 const loginBodySchema = z.object({
   username: z.string(),
diff --git a/src/api/handlers/nss.ts b/src/api/handlers/nss.ts
index 1c5a37d..05c7e68 100644
--- a/src/api/handlers/nss.ts
+++ b/src/api/handlers/nss.ts
@@ -1,7 +1,7 @@
 import { IMiddleware } from 'koa-router';
 
-import { NoSuchEntryError } from '../../model/errors';
-import Model from '../../model/model';
+import { NoSuchEntryError } from '../../model/errors.js';
+import Model from '../../model/model.js';
 
 export function getPasswd(model: Model): IMiddleware {
   return async (ctx, next) => {
diff --git a/src/api/handlers/shells.ts b/src/api/handlers/shells.ts
index f0da55c..b4c434e 100644
--- a/src/api/handlers/shells.ts
+++ b/src/api/handlers/shells.ts
@@ -1,5 +1,5 @@
 import { IMiddleware } from 'koa-router';
-import Model from '../../model/model';
+import Model from '../../model/model.js';
 
 export function getShells(model: Model): IMiddleware {
   return async (ctx, next) => {
diff --git a/src/api/handlers/users.ts b/src/api/handlers/users.ts
index 5396060..bf375b9 100644
--- a/src/api/handlers/users.ts
+++ b/src/api/handlers/users.ts
@@ -2,12 +2,12 @@ import { createPublicKey } from 'crypto';
 import { jwtVerify } from 'jose';
 import { IMiddleware } from 'koa-router';
 import z from 'zod';
-import Config from '../../config';
-import { EmailAddress } from '../../model/email_addresses';
-import { InvalidEmailError, ResendLimitExeededError, UserExistsError } from '../../model/errors';
-import Model from '../../model/model';
-import { sendEmail } from '../email';
-import changePasswordTemplate from '../templates/change_password_email_template';
+import Config from '../../config.js';
+import { EmailAddress } from '../../model/email_addresses.js';
+import { InvalidEmailError, ResendLimitExeededError, UserExistsError } from '../../model/errors.js';
+import Model from '../../model/model.js';
+import { sendEmail } from '../email.js';
+import changePasswordTemplate from '../templates/change_password_email_template.js';
 
 export function createUser(model: Model, config: Config): IMiddleware {
   const bodySchema = z.object({
diff --git a/src/api/router.ts b/src/api/router.ts
index 13de5b5..44752c8 100644
--- a/src/api/router.ts
+++ b/src/api/router.ts
@@ -1,9 +1,12 @@
 import bodyParser from 'koa-bodyparser';
 import Router from 'koa-router';
-import Config from '../config';
-import Model from '../model/model';
-import createOIDCRouter from '../oidc/routes';
-import { checkVerificationEmailToken, sendVerificationEmail } from './handlers/emails';
+import type OIDCProvider from 'oidc-provider';
+import type { Configuration as OIDCConfiguration } from 'oidc-provider';
+
+import Config from '../config.js';
+import Model from '../model/model.js';
+import createOIDCRouter from '../oidc/routes.js';
+import { checkVerificationEmailToken, sendVerificationEmail } from './handlers/emails.js';
 import {
   acceptGroup,
   applyGroup,
@@ -12,10 +15,10 @@ import {
   listMembers,
   listPending,
   rejectGroup,
-} from './handlers/groups';
-import { checkLogin, login, loginLegacy, loginPAM, logout } from './handlers/login';
-import { getGroup, getPasswd } from './handlers/nss';
-import { getShells } from './handlers/shells';
+} from './handlers/groups.js';
+import { checkLogin, login, loginLegacy, loginPAM, logout } from './handlers/login.js';
+import { getGroup, getPasswd } from './handlers/nss.js';
+import { getShells } from './handlers/shells.js';
 import {
   changePassword,
   checkChangePasswordEmailToken,
@@ -23,10 +26,8 @@ import {
   getUserEmails,
   getUserInfo,
   sendChangePasswordEmail,
-} from './handlers/users';
-import { changeUserShell, getUserShell } from './handlers/users';
-// @ts-expect-error: https://github.com/microsoft/TypeScript/issues/49721
-import type OIDCProvider, { Configuration as OIDCConfiguration } from 'oidc-provider';
+} from './handlers/users.js';
+import { changeUserShell, getUserShell } from './handlers/users.js';
 
 export function createRouter(
   model: Model,
diff --git a/src/api/server.ts b/src/api/server.ts
index 35f5bd2..bdb6b44 100644
--- a/src/api/server.ts
+++ b/src/api/server.ts
@@ -3,15 +3,15 @@ import * as Bunyan from 'bunyan';
 import * as crypto from 'crypto';
 import Koa from 'koa';
 import mount from 'koa-mount';
+import OIDCProvider from 'oidc-provider';
 
-import Config from '../config';
-import Model from '../model/model';
-import createOIDCConfig from '../oidc/configuration';
-import { createRouter } from './router';
+import Config from '../config.js';
+import Model from '../model/model.js';
+import createOIDCConfig from '../oidc/configuration.js';
+import { createRouter } from './router.js';
 
-const createServer = async (config: Config, log: Bunyan, inputModel?: Model) => {
+const createServer = (config: Config, log: Bunyan, inputModel?: Model) => {
   const model = inputModel ?? new Model(config, log);
-  const OIDCProvider = (await import('oidc-provider')).default;
   const oidcConfig = createOIDCConfig(model, config.oidc);
   const oidcProvider = new OIDCProvider(config.oidc.issuer, oidcConfig);
 
diff --git a/src/config.ts b/src/config.ts
index 0a3afdb..b2676f2 100644
--- a/src/config.ts
+++ b/src/config.ts
@@ -2,7 +2,6 @@
  * Configuration.
  */
 
-// @ts-expect-error: https://github.com/microsoft/TypeScript/issues/49721
 import type { ClientMetadata, JWKS } from 'oidc-provider';
 
 /**
diff --git a/src/index.ts b/src/index.ts
index fe63948..9129476 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,7 +1,7 @@
 import * as bunyan from 'bunyan';
 import * as fs from 'fs';
-import createAPIServer from './api/server';
-import Config from './config';
+import createAPIServer from './api/server.js';
+import Config from './config.js';
 
 const config: Config = JSON.parse(fs.readFileSync('config.json', { encoding: 'utf-8' }));
 
@@ -10,8 +10,8 @@ const log = bunyan.createLogger({
   level: config.logLevel,
 });
 
-async function run() {
-  const apiServer = await createAPIServer(config, log);
+function run() {
+  const apiServer = createAPIServer(config, log);
   apiServer.listen(config.api.listenPort, config.api.listenHost);
 }
 
diff --git a/src/model/email_addresses.ts b/src/model/email_addresses.ts
index 834c351..7728ef6 100644
--- a/src/model/email_addresses.ts
+++ b/src/model/email_addresses.ts
@@ -1,7 +1,7 @@
 import * as crypto from 'crypto';
 import moment from 'moment';
-import { ExpiredTokenError, NoSuchEntryError } from './errors';
-import Transaction from './transaction';
+import { ExpiredTokenError, NoSuchEntryError } from './errors.js';
+import Transaction from './transaction.js';
 
 interface EmailAddressRow {
   address_local: string;
diff --git a/src/model/groups.ts b/src/model/groups.ts
index c3cd4f4..19a9df1 100644
--- a/src/model/groups.ts
+++ b/src/model/groups.ts
@@ -1,6 +1,6 @@
-import { NoSuchEntryError } from './errors';
-import Transaction from './transaction';
-import { Translation } from './translation';
+import { NoSuchEntryError } from './errors.js';
+import Transaction from './transaction.js';
+import { Translation } from './translation.js';
 
 interface GroupRow {
   idx: number;
diff --git a/src/model/hosts.ts b/src/model/hosts.ts
index 9cb6703..56bd908 100644
--- a/src/model/hosts.ts
+++ b/src/model/hosts.ts
@@ -1,6 +1,6 @@
-import { AuthorizationError, NoSuchEntryError } from './errors';
-import Model from './model';
-import Transaction from './transaction';
+import { AuthorizationError, NoSuchEntryError } from './errors.js';
+import Model from './model.js';
+import Transaction from './transaction.js';
 
 interface HostRow {
   idx: number;
diff --git a/src/model/model.ts b/src/model/model.ts
index 34a9fa4..b4fae2c 100644
--- a/src/model/model.ts
+++ b/src/model/model.ts
@@ -1,15 +1,15 @@
 import * as Bunyan from 'bunyan';
 import * as pg from 'pg';
-import Config from '../config';
-import EmailAddresses from './email_addresses';
-import { ControllableError } from './errors';
-import Groups from './groups';
-import Hosts from './hosts';
-import OAuth from './oauth';
-import Permissions from './permissions';
-import Shells from './shells';
-import Transaction from './transaction';
-import Users from './users';
+import Config from '../config.js';
+import EmailAddresses from './email_addresses.js';
+import { ControllableError } from './errors.js';
+import Groups from './groups.js';
+import Hosts from './hosts.js';
+import OAuth from './oauth.js';
+import Permissions from './permissions.js';
+import Shells from './shells.js';
+import Transaction from './transaction.js';
+import Users from './users.js';
 
 const PSQL_SERIALIZATION_FAILURE = '40001';
 const PSQL_DEADLOCK_DETECTED = '40P01';
diff --git a/src/model/oauth.ts b/src/model/oauth.ts
index 058079f..3c98df3 100644
--- a/src/model/oauth.ts
+++ b/src/model/oauth.ts
@@ -1,8 +1,7 @@
-// @ts-expect-error: https://github.com/microsoft/TypeScript/issues/49721
 import type { AllClientMetadata } from 'oidc-provider';
 
-import { NoSuchEntryError } from './errors';
-import Transaction from './transaction';
+import { NoSuchEntryError } from './errors.js';
+import Transaction from './transaction.js';
 
 export default class OAuth {
   public async getClientById(tr: Transaction, id: string): Promise<AllClientMetadata> {
diff --git a/src/model/permissions.ts b/src/model/permissions.ts
index 511dafd..897b8f2 100644
--- a/src/model/permissions.ts
+++ b/src/model/permissions.ts
@@ -1,7 +1,7 @@
-import { NoSuchEntryError } from './errors';
-import Model from './model';
-import Transaction from './transaction';
-import { Translation } from './translation';
+import { NoSuchEntryError } from './errors.js';
+import Model from './model.js';
+import Transaction from './transaction.js';
+import { Translation } from './translation.js';
 
 export default class Permissions {
   constructor(private readonly model: Model) {
diff --git a/src/model/shells.ts b/src/model/shells.ts
index f93e378..1063b0f 100644
--- a/src/model/shells.ts
+++ b/src/model/shells.ts
@@ -1,4 +1,4 @@
-import Transaction from './transaction';
+import Transaction from './transaction.js';
 
 export default class Shells {
   constructor() {
diff --git a/src/model/users.ts b/src/model/users.ts
index 7a1a8ff..dda6917 100644
--- a/src/model/users.ts
+++ b/src/model/users.ts
@@ -8,9 +8,9 @@ import {
   ExpiredTokenError,
   NoSuchEntryError,
   NotActivatedError,
-} from './errors';
-import Model from './model';
-import Transaction from './transaction';
+} from './errors.js';
+import Model from './model.js';
+import Transaction from './transaction.js';
 
 // see language enum in schema.sql
 export type Language = 'ko' | 'en';
diff --git a/src/oidc/account.ts b/src/oidc/account.ts
index 5ca3622..bf1e407 100644
--- a/src/oidc/account.ts
+++ b/src/oidc/account.ts
@@ -1,4 +1,3 @@
-// @ts-expect-error: https://github.com/microsoft/TypeScript/issues/49721
 import type { Account } from 'oidc-provider';
 
 class OIDCAccount implements Account {
diff --git a/src/oidc/adapter.ts b/src/oidc/adapter.ts
index a195a13..653c35d 100644
--- a/src/oidc/adapter.ts
+++ b/src/oidc/adapter.ts
@@ -1,9 +1,8 @@
-import Redis from 'ioredis';
-// @ts-expect-error: https://github.com/microsoft/TypeScript/issues/49721
+import { Redis } from 'ioredis';
 import type { Adapter, AdapterPayload } from 'oidc-provider';
 
-import { NoSuchEntryError } from '../model/errors';
-import Model from '../model/model';
+import { NoSuchEntryError } from '../model/errors.js';
+import Model from '../model/model.js';
 
 const grantable = new Set([
   'AccessToken',
diff --git a/src/oidc/configuration.ts b/src/oidc/configuration.ts
index 0175ed0..7ddcfe0 100644
--- a/src/oidc/configuration.ts
+++ b/src/oidc/configuration.ts
@@ -1,9 +1,8 @@
-// @ts-expect-error: https://github.com/microsoft/TypeScript/issues/49721
 import type { Configuration } from 'oidc-provider';
-import Config from '../config';
-import type Model from '../model/model';
-import OIDCAccount from './account';
-import AdapterFactory from './adapter';
+import Config from '../config.js';
+import type Model from '../model/model.js';
+import OIDCAccount from './account.js';
+import AdapterFactory from './adapter.js';
 
 const claims = {
   openid: ['sub', 'username', 'groups'],
diff --git a/src/oidc/redis.ts b/src/oidc/redis.ts
index cad4143..60cbf7f 100644
--- a/src/oidc/redis.ts
+++ b/src/oidc/redis.ts
@@ -1,5 +1,4 @@
-import Redis from 'ioredis';
-// @ts-expect-error: https://github.com/microsoft/TypeScript/issues/49721
+import { Redis } from 'ioredis';
 import type { Adapter, AdapterPayload } from 'oidc-provider';
 
 const grantable = new Set([
diff --git a/src/oidc/routes.ts b/src/oidc/routes.ts
index e98cbe4..41522d0 100644
--- a/src/oidc/routes.ts
+++ b/src/oidc/routes.ts
@@ -1,11 +1,11 @@
 import { strict as assert } from 'node:assert';
 
 import Router from 'koa-router';
-// @ts-expect-error: https://github.com/microsoft/TypeScript/issues/49721
 import type OIDCProvider from 'oidc-provider';
+import { errors as oidcErrors } from 'oidc-provider';
 import * as z from 'zod';
 
-import Model from '../model/model';
+import Model from '../model/model.js';
 
 const loginSchema = z.object({
   username: z.string().nonempty(),
@@ -24,13 +24,11 @@ export default (model: Model, provider: OIDCProvider) => {
   const router = new Router();
 
   router.use(async (ctx, next) => {
-    const { errors } = await import('oidc-provider');
-
     ctx.set('cache-control', 'no-store');
     try {
       await next();
     } catch (err) {
-      if (err instanceof errors.SessionNotFound) {
+      if (err instanceof oidcErrors.SessionNotFound) {
         ctx.status = err.status;
         const { message: error, error_description: desc } = err;
         ctx.body = { error, desc };
diff --git a/test/_setup.ts b/test/_setup.ts
index 0f51e27..15c4498 100644
--- a/test/_setup.ts
+++ b/test/_setup.ts
@@ -2,9 +2,9 @@ import test from 'ava';
 import Logger, * as bunyan from 'bunyan';
 import * as fs from 'fs';
 import { Server } from 'node:http';
-import createAPIServer from '../src/api/server';
-import Config from '../src/config';
-import Model from '../src/model/model';
+import createAPIServer from '../src/api/server.js';
+import Config from '../src/config.js';
+import Model from '../src/model/model.js';
 
 export let config: Config;
 export let log: Logger;
diff --git a/test/_test_utils.ts b/test/_test_utils.ts
index 019133c..b4a57f6 100644
--- a/test/_test_utils.ts
+++ b/test/_test_utils.ts
@@ -1,8 +1,8 @@
 import { Server } from 'node:http';
 import * as request from 'supertest';
 import { v4 as uuid } from 'uuid';
-import Model from '../src/model/model';
-import Transaction from '../src/model/transaction';
+import Model from '../src/model/model.js';
+import Transaction from '../src/model/transaction.js';
 
 export async function createEmailAddress(tr: Transaction, model: Model): Promise<number> {
   return await model.emailAddresses.create(tr, uuid(), uuid());
diff --git a/test/api/email.test.ts b/test/api/email.test.ts
index d2529a2..de73802 100644
--- a/test/api/email.test.ts
+++ b/test/api/email.test.ts
@@ -2,7 +2,7 @@ import test from 'ava';
 import * as nodemailer from 'nodemailer';
 import * as request from 'supertest';
 import { v4 as uuid } from 'uuid';
-import { app, config, model } from '../_setup';
+import { app, config, model } from '../_setup.js';
 
 test.skip('email configuration is correct', async t => {
   const emailOption = {
diff --git a/test/api/groups.test.ts b/test/api/groups.test.ts
index 7c63286..f036aa5 100644
--- a/test/api/groups.test.ts
+++ b/test/api/groups.test.ts
@@ -1,9 +1,9 @@
 import test from 'ava';
 import * as request from 'supertest';
 import { v4 as uuid } from 'uuid';
-import { GroupUserInfo } from '../../src/model/groups';
-import { app, model } from '../_setup';
-import { createGroup, createGroupRelation, createUser } from '../_test_utils';
+import { GroupUserInfo } from '../../src/model/groups.js';
+import { app, model } from '../_setup.js';
+import { createGroup, createGroupRelation, createUser } from '../_test_utils.js';
 
 test('group listing', async t => {
   const username = uuid();
diff --git a/test/api/login.test.ts b/test/api/login.test.ts
index 386915f..6c6cda2 100644
--- a/test/api/login.test.ts
+++ b/test/api/login.test.ts
@@ -3,8 +3,8 @@ import moment from 'moment';
 import * as request from 'supertest';
 import tweetnacl from 'tweetnacl';
 import { v4 as uuid } from 'uuid';
-import { app, config, model } from '../_setup';
-import { createAgentForwardedFor } from '../_test_utils';
+import { app, config, model } from '../_setup.js';
+import { createAgentForwardedFor } from '../_test_utils.js';
 
 test('test login with credential', async t => {
   let username = '';
diff --git a/test/api/nss.test.ts b/test/api/nss.test.ts
index 33a2a09..82ecc56 100644
--- a/test/api/nss.test.ts
+++ b/test/api/nss.test.ts
@@ -1,6 +1,6 @@
 import test from 'ava';
-import { app, config, model } from '../_setup';
-import { createAgentForwardedFor, createUser } from '../_test_utils';
+import { app, config, model } from '../_setup.js';
+import { createAgentForwardedFor, createUser } from '../_test_utils.js';
 
 test('fetch passwd entries', async t => {
   const agent = createAgentForwardedFor(app, '10.0.2.0');
diff --git a/test/api/shells.test.ts b/test/api/shells.test.ts
index a5475db..6bfddac 100644
--- a/test/api/shells.test.ts
+++ b/test/api/shells.test.ts
@@ -1,7 +1,7 @@
 import test from 'ava';
 import * as request from 'supertest';
 import { v4 as uuid } from 'uuid';
-import { app, model } from '../_setup';
+import { app, model } from '../_setup.js';
 
 test('test getShells', async t => {
   const newShell = uuid();
diff --git a/test/api/users.test.ts b/test/api/users.test.ts
index 11075f7..0e5099d 100644
--- a/test/api/users.test.ts
+++ b/test/api/users.test.ts
@@ -2,7 +2,7 @@ import test, { ExecutionContext } from 'ava';
 import * as crypto from 'crypto';
 import * as request from 'supertest';
 import { v4 as uuid } from 'uuid';
-import { app, config, model } from '../_setup';
+import { app, config, model } from '../_setup.js';
 
 test('create user step by step', async t => {
   const agent = request.agent(app);
diff --git a/test/model/email_addresses.test.ts b/test/model/email_addresses.test.ts
index 8ff6477..9aca077 100644
--- a/test/model/email_addresses.test.ts
+++ b/test/model/email_addresses.test.ts
@@ -3,8 +3,8 @@ import test from 'ava';
 import moment from 'moment';
 import { v4 as uuid } from 'uuid';
 
-import { model } from '../_setup';
-import { createEmailAddress, createUser } from '../_test_utils';
+import { model } from '../_setup.js';
+import { createEmailAddress, createUser } from '../_test_utils.js';
 
 test('create extra email', async t => {
   await model.pgDo(async tr => {
diff --git a/test/model/groups.test.ts b/test/model/groups.test.ts
index 0ae9f2d..d77d7e8 100644
--- a/test/model/groups.test.ts
+++ b/test/model/groups.test.ts
@@ -1,11 +1,11 @@
 import test from 'ava';
 
-import { NoSuchEntryError } from '../../src/model/errors';
-import { Translation } from '../../src/model/translation';
+import { NoSuchEntryError } from '../../src/model/errors.js';
+import { Translation } from '../../src/model/translation.js';
 
 import { v4 as uuid } from 'uuid';
-import { model } from '../_setup';
-import { createGroup, createGroupRelation, createUser } from '../_test_utils';
+import { model } from '../_setup.js';
+import { createGroup, createGroupRelation, createUser } from '../_test_utils.js';
 
 const name: Translation = {
   ko: '도지',
diff --git a/test/model/hosts.test.ts b/test/model/hosts.test.ts
index 229a930..2178abb 100644
--- a/test/model/hosts.test.ts
+++ b/test/model/hosts.test.ts
@@ -4,8 +4,8 @@ import { v4 as uuid } from 'uuid';
 
 import * as bunyan from 'bunyan';
 import * as fs from 'fs';
-import Config from '../../src/config';
-import Model from '../../src/model/model';
+import Config from '../../src/config.js';
+import Model from '../../src/model/model.js';
 
 const config: Config = JSON.parse(fs.readFileSync('config.test.json', { encoding: 'utf-8' }));
 
diff --git a/test/model/model.test.ts b/test/model/model.test.ts
index f502322..5319953 100644
--- a/test/model/model.test.ts
+++ b/test/model/model.test.ts
@@ -1,6 +1,6 @@
 import test from 'ava';
-import { model } from '../_setup';
-import { delay } from '../_test_utils';
+import { model } from '../_setup.js';
+import { delay } from '../_test_utils.js';
 
 test('resolve deadlock', async t => {
   const transactionStages: Array<number> = [0, 0];
diff --git a/test/model/permissions.test.ts b/test/model/permissions.test.ts
index d9420b2..508b201 100644
--- a/test/model/permissions.test.ts
+++ b/test/model/permissions.test.ts
@@ -1,9 +1,9 @@
 import test from 'ava';
 
-import { Translation } from '../../src/model/translation';
+import { Translation } from '../../src/model/translation.js';
 
-import { model } from '../_setup';
-import { createGroup, createGroupRelation, createPermission, createUser } from '../_test_utils';
+import { model } from '../_setup.js';
+import { createGroup, createGroupRelation, createPermission, createUser } from '../_test_utils.js';
 
 const name: Translation = {
   ko: '도지',
diff --git a/test/model/shells.test.ts b/test/model/shells.test.ts
index ca92032..052d545 100644
--- a/test/model/shells.test.ts
+++ b/test/model/shells.test.ts
@@ -1,6 +1,6 @@
 import test from 'ava';
 import { v4 as uuid } from 'uuid';
-import { model } from '../_setup';
+import { model } from '../_setup.js';
 
 test('get, add, and remove shells', async t => {
   const newShell = uuid();
diff --git a/test/model/users.test.ts b/test/model/users.test.ts
index bdd0a7e..3fcf0b0 100644
--- a/test/model/users.test.ts
+++ b/test/model/users.test.ts
@@ -3,10 +3,14 @@ import test from 'ava';
 import * as phc from '@phc/format';
 import moment from 'moment';
 import { v4 as uuid } from 'uuid';
-import { AuthenticationError, NoSuchEntryError, NotActivatedError } from '../../src/model/errors';
-
-import { model } from '../_setup';
-import { createGroup, createUser } from '../_test_utils';
+import {
+  AuthenticationError,
+  NoSuchEntryError,
+  NotActivatedError,
+} from '../../src/model/errors.js';
+
+import { model } from '../_setup.js';
+import { createGroup, createUser } from '../_test_utils.js';
 
 test('create and delete user', async t => {
   await model.pgDo(async tr => {
diff --git a/tsconfig.json b/tsconfig.json
index cd82808..cef8d4c 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,20 +1,21 @@
 {
   "compilerOptions": {
     "outDir": "dist",
-    "target": "es6",
+    "target": "ES2020",
     "lib": [
-      "es2018",
-      "dom"
+      "ES2020",
+      "DOM"
     ],
-    "module": "node16",
-    "moduleResolution": "node16",
+    "module": "NodeNext",
+    "moduleResolution": "NodeNext",
     "strict": true,
     "noUnusedLocals": false,
     "noUnusedParameters": false,
     "noImplicitReturns": true,
     "noFallthroughCasesInSwitch": true,
-    "downlevelIteration": true,
     "esModuleInterop": true,
+    "isolatedModules": true,
+    "importsNotUsedAsValues": "remove",
     "typeRoots": [
       "./node_modules/@types",
       "./typings"