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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.

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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
}
Sign up for an account
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
Account verification
Please enter the code sent to ***** ***456
5
3
2
1
3
2
Resend code
Submit details
Success!!
Your account has been verified.
Log in

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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Always on

Everything your business needs

Postcoder and its team of address and technology specialists meet the needs of high-demand applications and rapidly growing businesses.

  • ISO 9001 certified

    Built on quality management best practices you can trust.

  • Auto-scaling infrastructure

    Seamlessly handles enterprise volumes and traffic spikes.

  • PCI-DSS & GDPR compliant

    Designed for secure, privacy-first data handling.

  • 99.99%+ uptime

    Proven reliability to keep your integrations running smoothly.

  • 24/7 internal response team

    Our engineers are on standby 24/7 to respond to service disruptions.

  • Low-latency response times

    Fast, reliable API performance at all times, even under load.

  • Full API access & integrations

    Connect easily with your existing tech stack.

  • Full UK coverage

    Simple, secure OTP verification via SMS without the need for apps.

  • Dedicated onboarding specialist

    Personalised setup and best-practice guidance.

  • Migration assistance included

    Smooth transition from legacy systems or providers.

  • Free multi-channel support

    Get help via chat, email or phone - at no extra cost.

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Highly rated by customers

Award-winning with top performance, easy admin and great support

Businesses rate Postcoder 4.7 stars out of 5 on the world's most trusted software marketplace.

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  • "Having a more simplified checkout page with the help of Postcoder has had two major benefits to our business. Faster checkouts by customers who haven't had to type in their full address, a much simpler customer journey and a major reduction in data errors; where we saw a big drop in incorrect details entered."
    Alex Woods Digital Marketing Executive / Victorian Plumbing
  • "We picked Postcoder because the API is simple to use and it supports many countries which we want to scale out to."
    David Annez Head of Engineering / loveholidays
  • "The reason we like Postcoder is that the rooftop lat/long coordinates have proven to be far more accurate than any other service and Postcoder has hugely increased our successful delivery rates."
    Laura Bailey E-commerce Product Manager / Pasta Evangelists
  • "Postcoder offers a seamless integration with our services. It is very popular with our customers."
    James Gutterson Commercial Manager / Signicat
  • "Postcoder has been great; there has been a noticeable quality increase in our campaigns. In some the pickup rate went from 30% to 60-70% and our appointment ratings for a campaign went from a 15% average to 40% for one client!"
    Daniel Jones IT Technician / Lead Pronto
  • "Postcoder is a single API that provides all the features we need... Rather than integrate several APIs, we only had to integrate one."
    Carl Horn Head of Digital Servicing & Customer Transformation / Capquest
  • "Postcoder ensures that all the address data, the mobile number and the email addresses that our customers give us are correct. It really speeds up the process for our customers."
    Julie Taylor Operations Director / Barrhead Travel