OTP Generator
Generate secure one-time passwords (OTP) for authentication, verification, and security systems
OTP Generator
Generate secure one-time passwords (OTP) for authentication, verification, and security systems
OTP Type
Content & Settings
Generated OTPs
About One-Time Password Generation
One-Time Passwords (OTP) are temporary passwords that are valid for a single login session or transaction. They provide an additional layer of security in two-factor authentication systems, account verification processes, and secure transactions. Our OTP generator creates cryptographically secure random codes with customizable length and character sets.
- Cryptographically secure random number generation
- Customizable length from 4 to 10 digits
- Support for numeric, alphanumeric, and mixed formats
- Bulk generation for testing and development
- Various use cases: SMS, email, app authentication
OTP Types and Formats
OTP Formats
- Numeric: 6-digit codes (123456)
- Alphanumeric: Mixed letters and numbers
- Uppercase: Capital letters only
- Lowercase: Small letters only
- Custom: User-defined character sets
- Hex: Hexadecimal format
Common Lengths
- 4 digits: Basic PIN verification
- 6 digits: Standard SMS/email OTP
- 8 digits: Enhanced security applications
- 10 digits: High-security transactions
- Variable: Application-specific requirements
- Time-based: TOTP with expiration
Frequently Asked Questions
How to generate totp code?
To generate a TOTP code, you need a shared secret key and the current Unix timestamp. The algorithm (RFC 6238) divides the current time by a period (usually 30 seconds), then uses HMAC-SHA1 to produce a hash from which a 6 or 8 digit code is extracted. Use the utilAZ OTP generator to create TOTP codes instantly, or implement it in code using libraries like pyotp (Python), otplib (Node.js), or Google Authenticator compatible SDKs.
What is the difference between hotp and totp?
HOTP (HMAC-based One-Time Password) uses an incrementing counter to generate codes, so the code stays valid until it is used. TOTP (Time-based One-Time Password) uses the current time divided into intervals (typically 30 seconds), so codes expire automatically. TOTP is more widely used today because it does not require synchronizing a counter between client and server and provides automatic expiration for better security.
How to set up an otp generator for google authenticator?
To set up an OTP generator compatible with Google Authenticator, generate a base32-encoded secret key, then create an otpauth URI in the format: otpauth://totp/Label?secret=BASE32SECRET&issuer=YourApp. Encode this URI as a QR code for users to scan with the Authenticator app. The utilAZ OTP generator can produce secrets and codes that follow this same TOTP standard (RFC 6238, SHA-1, 30-second period, 6 digits).
How to get the 6 digit code without an authenticator app?
You can get a 6-digit TOTP code without an authenticator app by using a browser-based generator like utilAZ, a command-line tool such as oathtool, or a password manager that supports TOTP (like Bitwarden or 1Password). You need the original secret key that was provided when you set up 2FA. Enter the secret into any of these tools and it will generate the same time-based code that an authenticator app would produce.
Is totp more secure than sms?
Yes, TOTP is more secure than SMS-based OTP. SMS codes can be intercepted through SIM swapping, SS7 network vulnerabilities, or phone number porting attacks. TOTP codes are generated locally on your device using a shared secret, so they cannot be intercepted in transit. TOTP also works offline and is not dependent on cellular network availability, making it both more secure and more reliable.
OTP Generation Examples
Sample Generated OTPs:
OTP Implementation Examples
JavaScript Generation:
// Generate numeric OTP
function generateOTP(length = 6) {
const digits = '0123456789';
let otp = '';
for (let i = 0; i < length; i++) {
otp += digits[Math.floor(Math.random() * 10)];
}
return otp;
}
// Generate alphanumeric OTP
function generateAlphaNumericOTP(length = 8) {
const chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';
let otp = '';
for (let i = 0; i < length; i++) {
otp += chars[Math.floor(Math.random() * chars.length)];
}
return otp;
}
console.log(generateOTP(6)); // 123456
console.log(generateAlphaNumericOTP(8)); // A7B9K2M8Python Implementation:
import secrets
import string
def generate_numeric_otp(length=6):
"""Generate numeric OTP"""
return ''.join(secrets.choice(string.digits) for _ in range(length))
def generate_alphanumeric_otp(length=8):
"""Generate alphanumeric OTP"""
chars = string.ascii_uppercase + string.digits
return ''.join(secrets.choice(chars) for _ in range(length))
def generate_custom_otp(charset, length):
"""Generate OTP with custom character set"""
return ''.join(secrets.choice(charset) for _ in range(length))
# Examples
print(generate_numeric_otp(6)) # 123456
print(generate_alphanumeric_otp(8)) # A7B9K2M8
print(generate_custom_otp('ABCDEF0123456789', 10)) # Custom hex-likeOTP Security Best Practices
Generation Security:
Implementation Security:
Common Use Cases
- Two-factor authentication (2FA)
- SMS and email verification
- Password reset confirmation
- Account registration verification
- Transaction authorization
- Login attempt verification
- API access token generation
- Secure payment confirmation