- SMS API providers at a glance
- Eleven SMS API providers to look at
- Where to start for your business
- Who you're allowed to text with marketing in the UK
- Transactional texts versus marketing texts
- Questions to ask before you choose an SMS API
- Signs it's time to automate your texts
- My plain advice on choosing an SMS API provider
- Frequently asked questions
The best SMS API providers let your website, app or system send text messages automatically, from order updates and login codes to reminders. Some are global developer platforms, while others are simpler business texting services with an API. Eleven options follow in no particular order.
Text messages still get read. A booking reminder, a delivery update or a login code by SMS reaches people who'd never open the same email in time.
The eleven providers below are listed alphabetically and in no particular order, and every description comes from the provider's own website, read this week. If you plan to use texts for marketing as well, my guide to how SMS marketing works for small businesses covers the basics.
SMS API providers at a glance
I checked the free plan column on each tool's own website, as of Oct 2026. Yes means the site names a free plan, a free account, a free tier or an open source version. Trial only means a time-limited trial. Not stated means the pages I read named neither, even where there's a button inviting you to start for free, so check the vendor's page before you sign up.
| Tool | Type | Good for | Free plan |
|---|---|---|---|
| BulkSMS | Business SMS platform and API | Simple bulk texts and an API | Not stated |
| ClickSend | Business SMS and MMS via web, integration or API | Texts from the web or integrations | Not stated |
| Esendex | Business SMS and multichannel messaging | UK businesses texting customers | Trial only |
| Infobip | Business SMS service provider | Global, high-volume messaging | Not stated |
| Plivo | SMS API and marketing platform | Developers who also send campaigns | Not stated |
| Sinch | Enterprise-grade global SMS API | Enterprise messaging at scale | Not stated |
| SMSGlobal | SMS gateway service provider | Australian businesses and data | Not stated |
| Telnyx | SMS API built on carrier infrastructure | Control over the network itself | Not stated |
| Twilio | SMS API for business text messaging | Building custom messaging into an app | Trial only |
| Vonage | Communications APIs including SMS | Texts plus verification and voice | Not stated |
| Voodoo SMS | UK bulk SMS text marketing service | UK bulk texts on a free account | Yes |
Eleven SMS API providers to look at
BulkSMS
Best for: Small businesses that want a web messenger for bulk texts plus an SMS API to connect their own website or app.
ClickSend
Best for: Teams that want to send SMS and MMS from a web app, their existing tools or an API, whichever is easiest.
Esendex
Best for: UK organisations that want business SMS and other messaging channels with a free trial to test them.
Infobip
Best for: Larger businesses that want a global SMS provider with many other channels available as they grow.
Plivo
Best for: App builders who want an SMS API for alerts and logins plus marketing campaigns from the same provider.
Sinch
Best for: Enterprises that want a secure, global SMS API alongside RCS, WhatsApp, voice and verification.
SMSGlobal
Best for: Australian businesses that want an SMS gateway and API where their data stays in Australia, with local support.
Telnyx
Best for: Technical teams that want an SMS API from a provider running its own carrier infrastructure.
Twilio
Best for: Engineers who want a widely used SMS API with a free trial and documentation for almost any use case.
Vonage
Best for: Product teams that want SMS together with two-factor verification, voice and video APIs from one vendor.
Voodoo SMS
Best for: UK small businesses that want bulk SMS and an API, starting on a free account before they send at volume.
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Where to start for your business
- UK bulk texts on a free account: Voodoo SMS.
- Texting from a web app or integrations: ClickSend.
- Custom messaging inside your own app: Twilio.
- SMS plus two-factor verification: Vonage.
- Data kept in Australia: SMSGlobal.
Who you're allowed to text with marketing in the UK
The Information Commissioner's Office says you can email or text any corporate body, such as a company or a limited liability partnership. Individuals are different: you can only send them marketing texts if they've specifically consented, or if they bought a similar product from you and didn't opt out when given the chance.
That rule applies however easy the API makes sending. Alerts, receipts and login codes are a different matter from marketing, but promotional texts need the right permission first, and every message should make opting out simple.
Transactional texts versus marketing texts
Transactional texts are messages people expect because of something they did, like a booking confirmation or a password code. They need to be fast and reliable, so delivery speed matters most.
Marketing texts promote an offer or event. They need consent, a clear sender name and an easy way to opt out, and they work best when they're short, personal and well timed.
Questions to ask before you choose an SMS API
- Which countries can it deliver to reliably?
- Can I use my business name as the sender?
- Does it support two-way replies?
- How does it handle opt-outs automatically?
- Are there libraries for the language my app uses?
- Does it offer other channels, such as WhatsApp?
Signs it's time to automate your texts
- Someone texts reminders by hand. Automate them.
- Customers miss appointments. Send a reminder the day before.
- Login emails arrive too late. Offer a text code instead.
- Replies get lost on one phone. Route them to a shared inbox.
Do you make an SMS API or business texting service? Tool makers can ask to be considered for a featured place on this list.
My plain advice on choosing an SMS API provider
Send a test message to every country and network that matters to you before you commit. Delivery quality varies more between providers and regions than most people expect, and a code that arrives two minutes late is a lost sign-in.
Keep marketing and transactional texts separate, and keep both short. If you're writing the messages yourself, my article on SMS and email marketing best practices has tips that work for both channels.
Frequently asked questions
What is an SMS API?
An SMS API is a service that lets your software send and receive text messages automatically, without anyone typing them on a phone.
What can I use an SMS API for?
Common uses include login codes, booking reminders, order and delivery updates, alerts and marketing campaigns where people have consented.
Can I send marketing texts to anyone?
In the UK, the ICO says you can text corporate bodies, but individuals need to have consented or bought a similar product from you without opting out.
Do SMS APIs offer free trials?
Some offer free trials or free accounts. The free plan column above shows what each provider's own site says.
Can people reply to texts sent by an API?
Many providers support two-way messaging, so replies can go into your app, inbox or CRM.
Can I send texts without writing code?
Some providers offer a web app or integrations alongside the API, so non-technical teams can send messages too.
