# Numeric OTP Generator

Generate cryptographically secure one-time numeric codes (SMS / email verification, raffle codes, event pins) with configurable length (3-10 digits), bulk output, optional ambiguous-digit exclusion, and an optional expiry countdown. Uses crypto.randomInt, not Math.random.

> Canonical page: https://elysiatools.com/en/tools/otp-generator

- **Category:** Security

- **Keywords:** otp, one-time password, verification code, sms code, numeric code, pin, random, security, crypto, expiry

## Overview

This tool generates **static one-time numeric codes** for verification scenarios — the kind a service texts or emails to a user. It is intentionally distinct from the RFC 6238 / 4226 TOTP/HOTP generator (which derives codes from a shared secret + time/counter for authenticator apps).

Options:
- **Digits**: 4, 6 (the SMS default), 8, or a custom length from 3 to 10.
- **Count**: generate 1-100 codes at once (deduplicated so each is unique).
- **Group with spaces**: render codes like `123 456` for readability.
- **Exclude ambiguous (0, 1)**: drop easily-confused digits so codes read cleanly over the phone.
- **Expires after**: optional validity window (30 s / 1 / 5 / 10 min) shown as a countdown.

Security: randomness comes from Node's `crypto.randomInt()`, the cryptographically secure source — never `Math.random()`, which is predictable and unfit for codes.

Use cases: smoke-testing an SMS-OTP login flow, generating raffle/event pins, producing burnable verification codes for QA.

## Inputs

- **Digits** (select)
- **Custom length (3-10)** (number): e.g. 5
- **Count** (number): e.g. 1
- **Group with spaces (e.g. 123 456)** (checkbox)
- **Exclude ambiguous (0, 1)** (checkbox)
- **Expires after** (select)

## When to use

- When you need to generate secure, temporary numeric PINs or verification codes for mock testing SMS or email authentication flows.
- When creating bulk, unique raffle codes or event entry PINs that must be easily readable and free of confusing digits like 0 and 1.
- When you require cryptographically secure random numbers for one-time passwords instead of mathematically predictable values generated by standard browser APIs.

## How it works

- Select your desired code length from 3 to 10 digits, or choose standard presets like 4, 6, or 8 digits.
- Configure formatting options such as grouping digits with spaces for readability, excluding ambiguous numbers (0 and 1), and setting a countdown timer for code expiration.
- Specify the quantity of unique codes to generate (up to 100) and click generate to run the cryptographically secure random number generator.

## Use cases

- Smoke-testing SMS-OTP or email-based verification flows during application development.
- Generating batches of unique, easy-to-read raffle codes or event PINs for attendees.
- Creating temporary, burnable numeric codes for QA engineers to validate registration and login forms.

## Frequently asked questions

### Is this tool suitable for generating TOTP codes for authenticator apps like Google Authenticator?

No. This tool generates static, random numeric codes for SMS/email verification, not time-based (TOTP) or counter-based (HOTP) codes derived from shared secrets.

### How does the tool ensure the generated codes are secure?

It uses Node's cryptographically secure crypto.randomInt() function, ensuring the generated numbers are unpredictable and safe for verification scenarios.

### Can I generate multiple unique codes at the same time?

Yes, you can generate up to 100 unique, deduplicated codes in a single batch.

### What does the 'Exclude ambiguous' option do?

It filters out the digits 0 and 1, which are easily confused with letters like O, o, I, or l, making the codes easier to read aloud or transcribe.

### Does the expiry countdown actually invalidate the codes on my server?

No, the expiry countdown is a visual simulation for testing and UI demonstration purposes. You must implement actual code expiration logic on your backend.

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- [Web Image Processing Python Samples](https://elysiatools.com/en/samples/web-image-processing-python): Web Python image processing examples using PIL/Pillow including reading, saving, resizing, and format conversion
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- [Android Image Processing Kotlin Samples](https://elysiatools.com/en/samples/android-image-processing-kotlin): Android Kotlin image processing examples including reading/saving images, scaling, and format conversion
- [Web Image Processing Rust Samples](https://elysiatools.com/en/samples/web-image-processing-rust): Web Rust image processing examples including image read/save, scaling, and format conversion

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