Test emails and phones

Most of Clerk's sign-in and sign-up flows involve verifying ownership of an email address or phone number via a one time passcode (OTP). To confirm that your integration works correctly, you can simulate verification flows without sending an email or SMS, by using reserved values in test mode.

Verification messages are used during sign-up, sign-in, and when adding an email address or phone number to an existing account.


If Clerk is used to deliver SMS messages for your development instance, a maximum of 20 SMS messages can be delivered per calendar month.

After that, requests resulting in OTP SMS messages will be rejected. Other SMS notifications will still produce a webhook but won't be sent to the target number.

The following cases do not count toward the limit:

  • SMS messages sent to US numbers
  • SMS messages sent to test numbers
  • Self-delivered SMS messages (i.e. not delivered by Clerk)
  • SMS messages for apps with a paid subscription

If your development instance requires a higher allowance of monthly SMS messages, please contact support to request a limit increase.

Setup test mode

Every development instance has "test mode" enabled by default. If you need to use "test mode" on a production instance, you can enable it via the Clerk Dashboard or via the Backend API.


You should not be using "test mode" on any instance that manages actual customers.

Test mode via the Clerk Dashboard

To enable test mode via the Clerk Dashboard, navigate to the Settings page in the Clerk Dashboard. In the Enable test mode section, ensure the toggle is toggled on.

The 'Enable test mode' section of the Settings page in the Clerk Dashboard. There is a red arrow pointing to the toggled, which is toggled on.

How to use test mode

Once test mode is enabled, all you need to do is use the following test numbers as part of your standard flow.

Email addresses

Any email with the +clerk_test subaddress is a test email address. No emails will be sent, and they can be verified with the code 424242.

For example:

Phone numbers

Any fictional phone number is a test phone number. No SMS will be sent, and they can all be verified with the code 424242.

Fictional phone numbers have the following structure:

+1 (XXX) 555-0100 to +1 (XXX) 555-0199

For example:



Testing email links in E2E suites is an uphill task. We recommend turning on email verification codes, and using that flow to authenticate your tests. The flows are very similar.

Code examples

Testing sign in via email code

const testSignInWithEmailCode = async () => {
  const { signIn } = useSignIn();

  const emailAddress = "";
  const signInResp = await signIn.create({ identifier: emailAddress });
  const { emailAddressId } = signInResp.supportedFirstFactors.find(
    (ff) =>
      ff.strategy === "email_code" && ff.safeIdentifier === emailAddress
  )! as EmailCodeFactor;

  await signIn.prepareFirstFactor({
    strategy: "email_code",
    emailAddressId: emailAddressId,

  const attemptResponse = await signIn.attemptFirstFactor({
    strategy: "email_code",
    code: "424242",

  if (attemptResponse.status == "complete") {
  } else {
const testSignUpWithPhoneNumber = async () => {
  const { signUp } = useSignUp();

  await signUp.create({
    phoneNumber: "+12015550100",
  await signUp.preparePhoneNumberVerification();

  const res = await signUp.attemptPhoneNumberVerification({
    code: "424242",
  if (res.verifications.phoneNumber.status == "verified") {
  } else {


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