BUILT FOR DEVELOPERS, CODED FOR SIMPLICITY

Intuitive
SMS API
built to scale

Integrate two-way SMS, transactional alerts, and automated broadcasts into your tech stack in under 3 hours1 with our SMS API options, built for developers and no-code teams alike.

Built for high-volume and coded for simplicity, deploy SMS messages in minutes with our sms sending APIs, intuitive developer documents, and local, human support

Free trial
Developer documents
Illustration representing the Esendex SMS API and messaging platform
Trustpilot
Illustration showing SMS message integration and API code sample

How can I use an SMS API to send messages?

Our business SMS API options integrate the Esendex platform directly into your service platform or another software in your tech stack. This enables you to send, receive, and automate text messages seamlessly, decreasing deployment time and increasing operational efficiency.

With the Esendex API Product Suite, you have two brilliantly simple integration options – our multichannel REST API and our robust SMPP Protocol for high-throughput SMS volume.

Two brilliantly simple integrations
because sending SMS shouldn’t be complex

Unlock multichannel capabilities through our REST API

The Esendex multichannel REST API allows teams to dispatch universal reach SMS messages, but also automate rich media RCS messages, over secure HTTPS.

Instead of dealing with API sprawl across siloed platforms, our REST API delivers rapid connectivity that enables simple, multichannel integration.

Key benefits of our multichannel REST API:

  • Unify channel orchestration: Transition seamlessly between SMS and RCS with one parameter change.
  • Reduce time-to-value: Go from setup to live sending within 3 hours1.
  • Remove developer friction: Built with one JSON format, one base URL, and one API key.
Illustration of multichannel REST API workflow and code integration
Multichannel API (REST)
Illustration demonstrating high-volume SMS routing and integration using the Esendex SMPP protocol

Achieve high-volume SMS throughput with our SMPP Protocol

Our robust SMPP Protocol is the foundation for heavy-duty, mission-critical SMS outreach, allowing teams to control messaging traffic, stream high-volume sends over direct connections, and receive real-time insights without performance bottlenecks.

Perfect for high-volume, repetitive messaging such as system updates, promotional broadcasts, and internal operational alerts.

Key benefits of our SMPP Protocol:

  • High-throughput streaming: Reach thousands of recipients in one send with ultra-low latency.
  • Uninterrupted connectivity: Send messages without interruption with SMPP’s BIND architecture
  • Enhanced security and reliability: Secured via mandatory TLS 1.2+ or VPNs.

Built by developers, coded for simplicity.

Use our intuitive developer documentation to integrate our API Product Suite with your existing systems in as little as 3-hours1.

Code snippet illustrating a simple JSON payload and API request to send an SMS

API documents

World-class documentation and copy-pasteable code samples that are designed for multichannel, immediate deployment.

Developer Documents
Code snippet illustrating customers reviewing messages that were sent through our API.

Not a developer?

Our brilliantly simple, intuitive developer documents are easy to read and understand, even without a technical background.

Developer Documents

Why Developers choose Esendex’s API Product Suite

Unlike many SMS API service providers, Esendex brings over 20 years of business messaging experience and includes 24/7 support as standard rather than as a paid add-on.

Built for outcomes

Our multichannel REST API future-proofs your operations and eliminates API complexity with its modern architecture: one format, one base URL, and one API key.

Multichannel agility

Unlock multichannel scalability and unify channel orchestration by transitioning from SMS to RCS with one simple parameter change.

Fast integration

Reduce time-to-value and skip complex setup. Our modern architecture means you can set up your API in as little as 3 hours1, with dedicated local support included as standard.

Enterprise-grade security

Rest easy with an ISO 27001, ISO 27018 and Cyber Essentials certified supplier, supported by proactive 24/7 vulnerability scanning built to strict OWASP guidelines

Local, human support included

Direct access to UK-based technical engineers, with over 20+ years experience – bypassing premium paywalls and expensive support-tier subscriptions.

Universal, global reach

Send messages worldwide with confidence. Our direct carrier connections and in-country knowledge ensure reliable delivery across borders.

What will you send first through our SMS API?

Here are some of the most popular use cases on the World’s most popular messaging channel.

Marketing promotions

Tell your customers about upcoming offers and promotions.

Delivery updates and reminders

Send automated reminders to inform customers about appointment and delivery updates.

OTPs and verification messages

Send OTPs and MFA messages directly to your customer’s device to confirm their identity.

Employee comms

Provide company-wide internal updates with high-SMS throughput.

Scale your communication with these core SMS features

MASS TEXTING

Bulk SMS

Reach your customers instantly with time-sensitive updates and offers that are guaranteed to be seen and acted upon, driving service standards, immediate traffic and revenue.

Explore Bulk SMS

CUSTOMER SERVICE

SMS chat

Provide an easy way for your customers to effortlessly connect with you, without having to download an app or create a login. They simply use the SMS app that is on all mobile phones.

Explore SMS chat

STREAMLINE TOOLS

Email to SMS

Supercharge your email! Esendex Email-to-SMS enables you to send SMS from the comfort of your existing email. Enjoy the convenience of using the email platform you are used to, without the need to log into any additional software.

Explore Email to SMS

IMPROVE EXPERIENCE

SMS Surveys

Improve customer experience and get instant feedback from customers or staff, using engaging 2-way SMS surveys.

Explore our SMS Surveys

SMART AND SIMPLE

SMS Short Codes

Build brand recognition and boost response rates by using memorable five-digit numbers for promotions, surveys, or customer replies. Ideal for high-volume two-way messaging and brand recall.

Discover SMS Short Codes

INTEGRATE SMS

SMS Gateway

Experience peace of mind with enterprise-grade reliability and high-speed routing that ensures your alerts, codes, and notifications reach their destination on time, every time.

Explore our SMS Gateway

PERSONALISE SMS

SMS Sender ID

A business SMS Sender ID creates a professional impression while instantly notifying the end-user of your identity. Whether you choose your brand name, a customer representative’s name or a unique campaign, a customised ID boosts brand familiarity and engagement.

Explore our SMS Sender ID’s

How fast can you send your first SMS API message?

Take on our 5-minute challenge

Sign up for your free trial, grab your API key, and dispatch your first SMS via our REST API in under 5 minutes flat2.

Sign up for your free trial

Free Trial

Watch our attempt

Watch our engineer complete it in under 2 minutes and 20 seconds.

Trusted by UK businesses like Houseful to deliver time-critical property and appointment messaging at scale.

“Our estate agent customers need to send appointment reminders and property transaction updates reliably and on time. With SMS from Esendex, texts land straight into the hands of the agent’s clients when they are most valuable to them.”

Riccardo Dawson – Chief Operating Officer, Software at Houseful

Houseful case study
Houseful company logo, with a scenic city scape in the background.

Trust, compliance and reliability

Every SMS sent through the Esendex API Product Suite goes out from a dedicated short code, virtual mobile number, or verified sender ID, so recipients can see exactly who’s messaging them. Messaging is handled under the same GDPR-aligned processes and ISO 27001 and ISO 27018-certified infrastructure as the rest of the Esendex product suite, and because SMS works on any mobile phone without needing an app, data connection, or smartphone, delivery isn’t limited by device or network support the way richer channels can be. Combined with Esendex’s direct connections to mobile network operators across 190+ countries and adaptive routing that keeps delivery rates high, that gives you near-universal reach on a global scale.

SMS API FAQs

What is an SMS API?

An SMS API is a set of tools that lets software send and receive text messages automatically, without manual sending. Businesses use it to trigger messages like order updates, appointment reminders, or one-time passcodes directly from their own systems.

How much does the Esendex SMS API cost?

Pricing depends on message volume and destination. You can view current UK plans on our pricing page, or start with a 7-day free trial with no commitment.

Can I integrate the SMS API with Salesforce or Zapier?

Yes. The Esendex API works with platforms including Salesforce and Zapier, alongside pre-built message templates, so you can connect SMS to your existing workflows without custom development.

Can I send SMS internationally with the Esendex API?

Yes. The Esendex SMS API sends to over 190 countries, with local routing and compliance handled for you, so you can message customers wherever they are.

What phone number types does the Esendex SMS API support?

You can send from a dedicated short code, a virtual mobile number, or your own verified sender ID, with adaptive routing to keep delivery rates high across UK and international networks.

1 From Account setup and verification to first successful API SMS send. Based on the average time taken for a new REST API Prepay customer (03/25 – 05/26)

2 Based on our fastest customer integration time from free trial sign-up to first successful SMS message sent via API and independent in-house testing.

Insights

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