OTP verification API

One-time UK SMS password verification

Postcoder enables you to add two-factor authentication to your customer workflows using SMS text messages. Reduce fake signups, impersonation and account takeovers by adding OTP verification to your website and app.

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Your code is 532132. It expires in 5 mins.

Trusted by leading organisations worldwide

User-friendly authentication

OTP verification API

Postcoder OTP verification provides a user-friendly way to add an extra layer of protection to your services using SMS.

Delivers UK SMS one-time passcodes
No authenticator apps required
Ideal for users with UK mobile phones

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POST /pcw/PCW45-12345-12345-1234X/otp/send
{
	"to": "07500%20123456",
	"from": "Example.com"
	"message": "Your code is [otp]. It expires in 5 mins."
	"otplength": 6
	"expiry": 5
}
----
{
	"id": "OTP45-12345-12345-1234X"
}
POST /pcw/PCW45-12345-12345-1234X/otp/verify
{
	"id": "OTP45-12345-12345-1234X",
	"otp": "532132"
}
----
{
	"valid": true
}

We will verify your mobile number to create a 2-step verification for your account.

Name

Jo Smith

Email address

josmith100@gmail.com

Mobile number

07500 123456

Submit details

Please enter the code sent to ***** ***456

Resend code

Submit details

Your account has been verified.

Your code is 532132.

It expires in 5 mins.

"60% of consumers intentionally provide incorrect information when submitting their details online."
Source: Verve Research

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Verify, protect, trust

Enhance security with Postcoder OTP verification

Verify one-time passwords in real-time
Postcoder instantly checks if a one-time password (OTP) is correct and within its expiry time.
Customise OTP settings
Postcoder lets you set the code length, sender name and SMS message content to suit your application and brand.
Hello Jo, your security code is 532132. It will expire in 5 minutes. Do not share this code.
Control OTP expiry time
Postcoder allows you to control how long each OTP remains valid, balancing user convenience with protection against misuse.

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Authenticate users in real time

Secure and seamless authentication throughout your customer journey

Registration and onboarding
Prevent fake account creation and increase conversions by signing up and onboarding real customers only.
Logging in
Secure your authentication flows against account takeovers to maintain the security of customer accounts.
Confirming payments
Safeguard high-value transactions and purchases using one-time passwords to minimise payment fraud.

Managing accounts
Verify password resets, personal detail updates and any other account changes to protect customer data.
Recovering accounts
Provide another way to recover accounts when customers lose access to the email address on their account.
Verifying mobile numbers
Confirm customers have access to the phone number they provided to ensure you have a means to contact them.

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Global scale

OTP verification at scale

Postcoder delivers the scale you need for global commerce. It provides lightning quick responses and supreme reliability wherever your customers are based.

99.99_%
API uptime

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Highly rated by customers

An award-winning API with top-tier performance, easy admin and great support

Customers love Postcoder according to independent user reviews on the world's most trusted software marketplace. Start a free trial and find out what you've been missing.

Simple, straightforward and easy to integrate

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100% developer-friendly

An optimised developer experience

Get up and running with OTP verification in minutes using the quick start guide, sample code and API docs.

Handles spaces and non-numerics
Uses two API calls - send and verify (free)
Includes free multi-channel support

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otp.js

otp.py

otp.php

otp.cs

// Prepare request URL
let url = `https://ws.postcoder.com/pcw/${key}/otp/send`

// Return JSON ♥
url += `?format=json`;

// Tag request for easy reporting
url += `&identifier=signup_form`;

// Prepare request body
let body = {
	to: `${user_mobile_number}`,
    from: `Example.com`,
    message: `Your code is [otp]. It expires in 5 mins.`,
    otplength: 6,
    expiry: 5
};

POST /pcw/PCW45-12345-12345-1234X/otp/send?format=json&identifier=signup_form

{
	"to": "07500%20123456",
    "from": "Example.com",
    "message": "Your code is [otp]. It expires in 5 mins.",
    "otplength": 6,
    "expiry": 5
}
----
SMS message sent to 00447500123456:

Your code is 532132. It expires in 5 mins.

Simplified admin

Buy credits, check usage and configure security with ease

Use the feature-rich admin area to set up and manage your account. It is natively mobile and desktop-friendly so whether you're updating a setting on the go or doing a deep-dive at your desk, it will be the same seamless experience. It supports dark mode too.

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Powerful customer stories

Postcoder is trusted by over 9,000 organisations of all sizes

Postcoder helps organisations in the UK and worldwide achieve measurable improvements in their form conversions and data quality. After integrating Postcoder, many of them report increased onboarding numbers, faster form completion, and a surge in quality leads. Postcoder captures contact details you can rely on.

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