# aut2fa FAQ

> aut2fa is an API that sends one-time verification codes (OTP, 2FA). This page answers the common questions about it: how test keys work, what happens to a code that isn't delivered, retries, rate limits, pricing and WhatsApp delivery. Each answer is also on the page it belongs to.

Source: https://aut2fa.com/faq · Updated on 2026-10-11

## Questions

### How do test keys work?

Keys that start with `ak_test_` are free, and codes aut2fa generates in test mode are always `000000`. Automated tests can run the whole flow without touching your balance.

### What if a code isn’t delivered?

Nothing. The send is marked as failed, your balance stays the same, and your statement shows the failure.

### How do you protect against SMS pumping?

Every account has a ceiling on sends per minute. You can also turn on limits per application: sends per minute and sends per recipient per hour. Requests over a limit get a 429 with a `Retry-After` header, before anything is sent.

### Is it safe to retry a request?

Yes, with an `Idempotency-Key` header. Repeating a request with the same key returns the original send instead of sending a second code.

### Can I send my own code?

Yes. Pass it in the `code` field, or leave the field out and aut2fa generates one. Set `locale` to `en` or `pt-BR` to choose the message language.

## Pricing questions

### Is there a free plan?

Yes. New accounts receive 10 free live sends through any channel. After using this allowance, add balance to keep sending. Test keys (`ak_test_`) are free and run the whole flow with the code `000000`.

### Which channels can I use today?

The tables above list the channels currently available for delivery. Each shows suggested quantities, the total cost and the price per code.

### Do I pay for codes that aren't delivered?

No. A send that no channel delivers is marked `failed` and costs nothing; your statement shows the failure.

### Can I pay in another currency?

Not today. Balance and prices are in Brazilian reais (BRL).

## WhatsApp OTP questions

### What if the phone number has no WhatsApp?

aut2fa can't deliver the code, so the send ends as `failed` and costs nothing.

### How long is the code valid?

10 minutes from the moment you create the send. After that, `/verify` answers with `verification` set to `expired`.

### What happens after 5 wrong codes?

The send is locked: `verification` becomes `locked` and no further code is accepted. Create a new send to try again.

### Can I test for free?

Yes. Keys that start with `ak_test_` are free and the code aut2fa generates for a test send is always `000000`, so automated tests run the whole flow without touching your balance.

- [Start free](https://app.aut2fa.com/signup)
- [Read the docs](https://doc.aut2fa.com)