RCS API

Scale customer communication with our RCS API (REST)

Integrate with our multichannel REST API and drive engagement with automated branded messages, images, quick-reply buttons, and interactive links straight into your customer’s native messaging app.

Built for outcomes, coded for simplicity. Our RCS API (REST) is engineered with one URL base, one API key, a unified JSON structure, and copy-pasteable code samples for immediate RCS deployment.

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Developer documents
A smartphone graphic displaying a branded rich communication services (RCS) message with high-resolution imagery and interactive quick-reply buttons.
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A side-by-side smartphone comparison showing a rich media RCS message with branding and interactive buttons next to its standard text SMS fallback alternative.

What is an RCS API (REST)?

An RCS API (REST) is the developer interface that lets your systems programmatically build templates, dispatch RCS messages, and automate rich media messages over secure HTTPS.

Instead of dealing with API sprawl across siloed platforms, our RCS business messaging API (REST) delivers rapid connectivity that enables simple, multichannel integration – backed by robust SMS fallback to ensure maximum reach on a global scale.

Why technical teams choose our multichannel REST API

Built for outcomes

Our RCS API (REST) 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 API 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.

Enterprise-grade security

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

Why RCS is the future of text messages

Rich media & content

Convert engagement into sales by turning text-only promotions into shoppable experiences with rich images, video, audio, and PDF files.

Clickable CTAs

Prompt customer action by replacing plain text and generic hyperlinks with eye-catching and clear in-thread CTAs.

Verified brand identity

Eliminate spam and fraud concerns by displaying your official logo and brand name on a verified profile.

SMS fallback and global reach

Increase deliverability with SMS channel fallback on your RCS messages, ensuring messages are sent even without an internet connection.

An illustration showcasing key RCS messaging features, including verified sender branding, rich media carousels, and suggested reply buttons.

RCS messaging types

RCS for Business messages are segmented into three distinct types that cater for varied customer communication journeys and specific business needs, driving both capabilities and billing.

Basic messages: High-trust notifications and OTPs

Streamlined text-only RCS messages with verified branding. The closest thing to an enhanced SMS. Perfect for one-off notifications where you want a verified sender but don’t need rich media.

Simple plain-text messages delivered with maximum trust and zero friction.

Popular use cases include:

  • Authentication and 2FA
  • Security and fraud alerts
  • Transactional updates
  • Welcome messages
A smartphone mockup displaying a basic, text-based RCS notification.
A smartphone graphic illustrating a single, one-way promotional RCS message sent from a brand to a customer.

Single messages: High-impact action messages

Verified, extended text messages with rich cards with embedded media and action buttons, increasing purchasing opportunities and customer engagement.

High-converting visual messaging driving higher engagement than plain text messages.

Popular use cases included:

  • Marketing promotions
  • Cart reminders
  • Service reminders
  • Booking and appointment reminders
  • Document sending

Conversational messages: Interactive two-way support

Open two-way messaging sessions for real-time dialogue between customers and support agents, or automated chatbots.

Conversational messages reduce support call volumes and boost customer satisfaction.

Popular use cases include:

  • Inbound customer support
  • Query triage
  • Customer feedback surveys
  • Appointment management
A smartphone mockup showing a two-way conversational RCS chat between a customer and a brand's automated service.

“The Esendex range of products greatly enhance the way we speak with our customers from sales follow-ups and engineer appointment confirmations, all the way through to general Q&As.”

Arron Alderson – Solutions and Process Manager, Vaillant

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Built by developers, coded for simplicity.

Our multichannel REST API and intuitive developer documentation enable teams to go from zero to sending in under 3 hours1. Skip the complex setup and benefit from simple modern architecture with world-class documentation and free, local, human support.

A graphic displaying code snippets and developer documentation for integrating the Esendex RCS API.

API documents

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

Developer Documents
An illustration representing the Esendex web-based messaging platform, designed for users without developer experience.

Not a developer?

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

Developer Documents

Why choose Esendex as your RCS API provider?

Every RCS messaging API provider can list “rich messaging” as a feature. Where we truly stand out is when it matters most: message deliverability, enterprise-grade security, and true local, human-led support.

Google accredited partner

Our partnership gives you access to Google Support, native Android carrier routing, streamlined business onboarding, and verification.

Local, human support included

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

5B+ messages sent each year

The Esendex product suite delivers 5B+ messages annually across global carrier networks with 99% availability.

Trust, compliance and reliability

Every RCS message sent through the Esendex API Product Suite carries a verified business profile, so customers can see who they’re really talking to. Messaging is handled under the same GDPR-aligned processes and ISO 27001-certified infrastructure as the rest of the Esendex product suite, and when a device, network, or customer can’t receive RCS, messages fall back automatically with robust SMS fallback rather than failing to deliver, giving near-universal reach on a global scale.

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How fast can you send your first message?

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

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Watch our attempt

Watch our engineer complete it in under 3 minutes.

RCS API FAQs

What’s the difference between RCS and SMS?

SMS is a universal, text-only channel delivered over the mobile network and supported by every handset. RCS (Rich Communication Services) uses mobile data or Wi-Fi to deliver messages, enabling richer content such as images, videos, buttons, and branded business profiles. Read our guide to learn more. 

Can all devices receive RCS messages?

RCS messaging is available on Android devices running version 5.0 or higher, and on iPhones using iOS 18.2 or later. If a device doesn’t support RCS, our API automatically falls back to SMS.

Is the multichannel REST API secure and GDPR compliant?

Yes. The Esendex API is fully compliant with GDPR and ISO 27001.

How quickly can I start sending messages with the multichannel REST API?

Most teams send their first SMS message in under three hours thanks to our intuitive development documentation and our REST APIs modern architecture.

Do I need coding skills to use the multichannel REST API?

No. Our intuitive developer docs are designed for simple self-serve usage. If you don’t have the resources to integrate our API yourself, reach out to our support team, who will be happy to assist

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.

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