What is an SMS API?
API stands for Application Programming Interface. It is a set of protocols that dictates how two applications communicate with each other. These days, APIs are used to connect different pieces of software that perform discreet tasks together.
An SMS API is an API that allows an application to easily send SMS text messages through standard web frameworks. The API might handle sending a verification code via SMS to authorize a login, or it could automate bulk SMS messages like welcome text messages or marketing text messages to users.
Why is an SMS API Important for Business?
SMS is now a crucial component of two-factor authentication and login. Most apps need to confirm that a user is authenticated to access their account via either an SMS verification or email verification.
An SMS API also allows you to track and analyze the messages you send to users. You can track open rates, and delivery receipts, and determine how people behave after opening a text, and which messaging is proving to be most effective for your goals.
The Top SMS APIs (Updated 2024)
We’ve put together this list of the top SMS APIs in 2024 to help you decide which API is right for your needs. We evaluated APIs based on price, ease of integration, customer support, top features, customer reviews, and who each API is best for.
Twilio - Best Overall
Twilio is undoubtedly the leader in SMS API solutions with over 100 billion messages sent and received through its platform every year. It has a rich and extensive feature set including message cues, shortcodes, read receipts, MMS support, international phone number options, and both calling and messaging solutions. The API is one of the most reliable of any on this list.
Twilio is well-documented and used by many developers, so answers to your questions are not hard to find. There are SDKs available for nearly every language, and lots of official and unofficial support channels.
You get $15.50 worth of credits to try out Twilio’s messaging services. They have a super easy-to-follow onboarding flow that takes you through getting your first Twilio number (for free) and then guides you through sending a test SMS and shows you the code snippet that you can copy/paste into your own app to make it work:
Once you’ve sent your first test code, either from their UI sandbox of by copy-pasting the code into your terminal or application, they drop you into a resources page with guides on how to set up SMS messaging for various services. Clicking into an example will display set-by-step instructions on how to set up the service in your own app.
Pros
- Well-documented and support is easy to find
- Robust API
- Rich feature set
Cons
- Expensive
Reviews
“The best thing about Twilio is that it is straightforward to implement. Twilio SDKs are easy to use, and you can integrate it into your product for SMS or Email service within minutes.”
“While we can make outbound calls just fine, the biggest pain point we have with Twilio is the inability to answer incoming calls. If the customer is assigned to a specific user in our CRM, it will forward to their personal cell phone, but we'd rather be able to answer it from within our CRM.”
“Twilio is the best API provider for Text(SMS), Voice and Video calls. Twilio also provides APIs for the WhatsApp. But for that, we have to create our account on Meta. Twilio is the best choice when it comes to handling international services.”
Pricing
Twilio’s pricing starts at $0.0079 per message for inbound and outbound SMS, for both shortcodes, longcodes, and toll-free numbers. There are volume discounts after 150,000 messages per month ($0.0002 per every 150,000 messages.)
Best For
Enterprise, large teams, those looking to scale fast
Messagebird - Best for Large Teams
Messagebird has direct-to-carrier contracts with prominent companies like Facebook, Uber, and WhatsApp, meaning it is highly reliable and has great scalability when it comes to interfacing with these companies.
As well as giving users direct access to its SMS API, Messagebird also features an easy-to-use drag-and-drop interface for less tech-savvy users who need to interface with the API without code. Messagebird offers automated message sending, phone number verification, SMS to email, email marketing, and more.
MessageBird advertises that you can start for free, however, once you actually get into the dashboard you discover that in order to use SMS, you need to buy a phone number. US phone numbers are only $0.11/month, so it’s not a huge expense to test. However, you will have to go through the process of adding a credit card and credit to your wallet, which is a pain when you’re just trying to test a service out.
Once you’ve purchased a number, you can install the SMS functionality on a channel, and enable the channel. From there, you’ll be provided with documentation and resources to help you get the SMS functionality up and running in your own app. Overall, MessageBird is more difficult to get started with than Twilio, but it looks like the phone numbers and services are a little cheaper.
Pros
- Contracts with global carriers mean the API is robust and scalable
- Easy-to-use code-free interface
- Good documentation
Cons
- Some customers report API can be laggy
- Price equivalent to Twilio
Reviews
“MessageBird is an excellent WhatsApp API service provider. MessageBird also supports other social media communication channels like Facebook (Meta) Messenger, Instagram etc.”
“There are a few limitations to MessageBird. 1) It doesn't have complete control on WhatsApp APIs. We'll have to create an account on Meta, and once approved, we can use it. 2) Sometimes, API takes much more time to respond. 3) Cost is a bit high.”
“It's virtually free, and we've had great success driving incoming messages through our WhatsApp API connection. We also have Facebook and Instagram messages coming through to our inbox so we never miss a thing.”
Pricing
Messagebird pricing starts at $0.008 per message, but they offer discounts for bulk messaging and committed use. They also offer a few free solutions like a chat support widget for your website.
Best For
Large teams who primarily need to interface with Facebook, Instagram or WhatsApp
Plivo - Best for Reasonable Price
Similar to Twilio, Plivo is widely used and hence has an extensive global network of dedicated users. This means frequently asked questions are easy to answer without having to rely on Plivo support. There are a number of SDKs and excellent documentation for solutions in almost every programming language.
Unlike Twilio, Plivo is fairly cheap, making it a good alternative for those looking for something reasonably priced. Plivo has support for automated messaging, SMS verification, MFA, SMS surveys, appointment reminders, and marketing campaigns.
Pros
- Cheaper than Twilio or Messagebird
- API is highly available and extremely reliable
- Global coverage
Cons
- Support is reported to be lacking since it migrated overseas
- Some users report the platform is confusing
Reviews
“Plivo is a pretty easy platform to understand, especially with a background of working at a SaaS company. Plivo is our chosen SMS provider for our advocate/supporter activation texts - I haven't had any need to reach out to support, though, so I can't comment on their customer service level.”
“Things changed with them. They used to be responsive and helpful; they are no longer. Support is overseas now, and they simply 'client blame' all issues. They can't tell where a breach comes from when it happens - and it will.”
“Plivo's strongest feature is its robust and easy-to-use API for Voice and SMS communication. The API allows developers to easily integrate and build a variety of communication features into their applications.”
Pricing
Plivo’s pricing tiers start at just $0.005 to send an SMS and are free to receive for long codes, $0.0055 for toll-free numbers, and $0.0045 for shortcodes. For multimedia SMS messages, prices start at $0.016 to send. Bulk and committed use discounts are available. Contact the company for rates.
Best For
People looking for a cheaper alternative to Twilio, who aren’t put off by a lack of customer support.
Telnyx - Best for Price
Telnyx may be the cheapest option on this list, but they still offer a feature set comparable to Twilio and Messagebird. Their solutions include global coverage, automated sending and receiving, MFA, message queueing, and MMS support.
Users report that the interface is easy to use and that sales representatives are readily available to provide a range of flexible, highly customized solutions.
Before you can start using Telnyx’s services, they want you to upload an identification document, which feels unnecessary and is a huge pain in the ass, especially when you’re just trying to test out the service. They accept passport, driver’s license, ID card, or permanent residence documents.
They also don’t allow you to upload an existing picture of your documents - they force you to use their extremely complicated system that involves using a QR code to send a link to your phone. Overall, the pain of this experience was enough to make me give up on this API.
Pros
- Almost 70% cheaper than Twilio
- Excellent customer support
- Easy-to-use interface
Cons
- Documentation is somewhat lacking
- No direct-to-carrier relationships mean their low price is actually not as low as it appears
Reviews
“I recently started using Telnyx for my business communication needs, and I have to say, I'm really impressed with their service. One of the things I like best about Telnyx is their affordability - compared to other providers I've used in the past, Telnyx is significantly cheaper, which is great for my bottom line.”
“There were some bugs that I encountered while setting up the Messaging API. It seems recurring and some documentations are outdated. Onboarding can be a little bit easier, especially the Level 2 Verification System.”
“Ease of use - Portal page is fairly straightforward and has a nice clean, modern look and feel, which is also functional. Tech Support - contacting someone is pretty quick and easy. Web chat is quite helpful and usually located in the bottom right corner of the portal; typically, I get a response within a few minutes.”
Pricing
Telnyx pricing starts at just $0.004 to send and receive messages via longcode, $0.0055 for toll-free numbers, and $0.007 for shortcodes. However, because they have no direct-to-carrier relationships, you pay an additional $0.0001 - $0.005 depending on the carrier.
Best For
Those looking for a very cheap solution with great support
Messente - best for global reach
Messente is a cloud-based messaging solution that helps businesses communicate with their customers through SMS messaging. It offers a variety of features, including the ability to send and receive messages, schedule messages, and track delivery status.
It offers a pay-as-you-go pricing model, so you only pay for the messages you send.
Messente gives you just 1 euro worth of credit to test their API, so it’s a good idea to familiarize yourself with the documentation and know exactly what you are trying to do before signing up for a free trial.
It costs just $0.02 to send a test SMS, but you are limited to letters only and will have to use the Messente Sender Name, rather than your own.
Once you’ve sent some test SMS and established and verified your account, Messente doesn’t give you much guidance as to what to do next. Unlike Twilio there are no extensive onboarding tutorials, however, the Developers tab reveals documentation, quick-start guides, and some code snippets that can be copied. They also send you a welcome email with some getting started resources.
Overall, the API is more basic and less fully-featured than Twilio’s, and with less extensive support for getting started with the service.
Pros
Easy-to-use API
Pay-as-you-go pricing
Global reach
Cons
Some users have reported that the customer support can be slow at times
Can be expensive for high-volume users
Reviews
"Excellent tool with fair pricing to add SMS functionality to your app or project"
"The API documentation is easy to use and provides clear instructions"
"Cost is one of the main problems, as it's really expensive to send SMS messages, especially if your business includes sending large volumes of SMS like ours"
Pricing
Pay-as-you-go pricing starts at $0.009 per message. Volume discounts are available for high-volume users.
Best for
Businesses that need to send SMS messages to a global audience
Vonage - Best for Reliability and Security
Vonage provides several communications APIs, which are trusted globally by over 100k businesses. In addition to their SMS API, they provide a verification API, plus a data analytics and reports API to track the effectiveness of your messaging campaigns.
Vonage’s SMS API puts privacy and security first, and its adaptive routing technology means it has an edge when it comes to coverage and delivery. You will pay a slight premium for these features, but overall, it is a robust and feature-rich solution.
At first glance, it appears as though Vonage doesn’t offer a free account - the main CTA on their homepage is “Contact Us” implying that you need to talk to a sales rep to get started. However, clicking around through the “Login” screens reveals a signup form for a free account.
Once you get through signup, you are taken through a brief onboarding that establishes what language you’ll be using (Javascript isn’t an option, weirdly) and how you want to use Vonage.
I was presented with a message that there was an issue activating my free number. I’m not sure whether this is a frequent occurrence when signing up for this service. There are code snippets that can be copy-pasted into your code, or you can use the testing sandbox to send a test message. You have 2 euros worth of free credit, and each test SMS costs $0.04.
Pros
- Guaranteed 99.95% uptime
- Numbers available in more locations than any other provider
- Strong emphasis on privacy and security
Cons
- On the upper end of the price scale
- Customer service was reported to be weak
Reviews
“I have been a Vonage customer for many years (probably over 15) and, until the past month I’ve been very satisfied. They offer a great list of features and voice quality has always been good. Until recently, every time I’ve called for support I’ve always gotten an English speaking human being on the phone.”
“Worse customer service.
Untrained unprofessional staff to handle the call.
I used their service more then 10 years.
When I want to switch to another company they gave me very hard time .
It took months for switching.”
“It took me hours to get my VoIP phone up and running. The phone was connected to the ethernet but for some reason it didn’t work. Had to take the phone to my home because I don’t have a PC at the business for them to use remote control. I literally was on the phone with them for over 2 hours.”
Pricing
Vonage’s pricing starts at $0.0068 to send and message and $0.0062 to receive through a virtual phone number. The price is the same for toll-free numbers and shortcodes. Discounts are available if you bundle the SMS service with another of their APIs.
Best For
Those who require little customer support.
AbstractAPI
While not specifically an SMS API, AbstractAPI’s Phone Number Verification API is worth mentioning for its ease of use and competitive pricing. While you won’t be able to automate marketing campaigns, sending SMS messages, or get detailed analytics, you can use the service to verify a phone number.
The API is straightforward, offering a simple REST endpoint that accepts either one request at a time for verification, or can accept a CSV file for bulk phone number verification. The documentation is clear and you can get started for free.
Sign up for a free account with an email and password, and you’ll land on a dashboard with links to documentation, plans, and support. To test the service, you can use the sandbox provided - just enter the phone number you want to verify as a string at the end of the URL under the “Live Test” tab.
Clicking through the tabs at the top of this input reveals copy-pastable code in all the major programming languages, which you can add to your own app to easily start sending requests to the API.
The API returns information in easy-to-parse JSON format, and includes a boolean as to whether the number is valid, as well as information about the number, including carrier and location.
Pros
- Simple to use, easy to get started
- Reasonably priced with monthly plans
- Phone number verification is reasonably accurate
Cons
- Cannot automate sending or receiving SMS
- Phone number validation only
Reviews
“Love the simplicity and the pre-built code snippets.”
“Their customer service is horrendous and our entire platform depends on their APIs. We are hitting our limits and have no way to upgrade due to a bug in their own code. Incredibly frustrating.”
“Easy to get started, and the documentation was clear. I like the blog tutorials that show you different ways to use the product.”
Pricing
AbstractAPI’s pricing structure differs from the rest of the APIs on this list because it is based on a monthly subscription, rather than pay-as-you-go. Plans start at $9/month for 1000 requests at 3 requests per second and range up to $499/month for 100,000 requests at 100 requests per second.
Best For
Those who need phone number validation only.
Bandwidth - Best for Small Businesses
Bandwidth operates its own network (in the US), meaning it can cut out the middleman charge that factors into most other APIs pricing. The company has contracts with big-name players like Google and Microsoft.
The API feature set is pretty standard: automated sending and receiving, group messaging, chatbots, SMS verification, and data analytics.
Pros
- Proprietary network means no middleman fees
- Multimedia message support
Cons
- Proprietary network may be less robust than a standard network
Reviews
“Portal access and able to make changes on the fly, without having to use a back-end ITSP team. Good and honest discussions with account manager. Able to assist in our growth, by opening up new countries/regions.”
“The Voxbone number footprint could be larger. Also the use of Zones could be better defined.”
“We currently utilize Bandwidth among other carriers as a product support out platform. Getting voice traffic in/out as well as text messaging requires a partner. Bandwidth is a great partner.”
Pricing
Bandwidth’s pricing starts at $0.004 per message for outbound SMS and $0.015 for outbound MMS. Toll-free numbers start at $0.0055 for outbound SMS and $0.0185 for outbound MMS. Shortcode outbound messages are $0.006 per message.
Best For
Small businesses who need to operate only within the US.
Clicksend - Best for Uptime
Clicksend is more than an SMS gateway provider - it also offers APIs for email, voice, and more. Their SMS gateway handles text message automation, SMS campaigns, transactional SMS, and two-way messaging.
Their API claims lightning-fast delivery, 100% guaranteed uptime, and 24/7 customer support via chat staffed by actual humans.
Of all the services on this list, only Clicksend included an explicit notification about the rules and regulations regarding privacy when it comes to sending SMS messages. It was included in the brief onboarding flow before I got to my dashboard - for those who value privacy and user protection, that may be something to note.
You get a 14-day free trial to test the service, and you have to purchase a number before you can send any messages. You can send messages only with text (no links) and only from the Clicksend sender name.
To send messages, you can either copy-paste code directly into your app or terminal, or use the handy composer included in their UI under “Quick SMS.” The sender allows you to input text and a phone number and send a single SMS.
Pros
- Excellent customer support
- Easy-to-use integrations and SDKs
Cons
- Very pricey unless you are using in bulk (and even then it is at the top of the list)
Reviews
"Clicksend is super easy to set up and it's so important in our day-to-day communication."
“What I like the least about this software is the pricing and payment method. Their pricing is higher compared to few platforms I have came across and their minimum top-up is $20.”
“We found it easy to upload our teams' numbers and track how many text messages went out. Easy to track billing.”
Pricing
Clicksend’s pricing starts at $0.0234 for outbound SMS when the volume is less than 5k messages for the month. Over 150k messages, which drops to $0.0083 (which is still higher than any other provider on this list.)
Best For
Those willing to pay more for guaranteed 100% uptime and good customer support
SimpleTexting - Best for Customer Support
SimpleTexting promises a simple, easily integrated API solution for all your communication needs. They offer customer support through phone, email, and chat, and their API handles automated sending and receiving, opt-in messages, unsubscribe requests, delivery reports, and data analytics.
Their pricing structure is different from others on this list, offering monthly subscriptions instead of pay-as-you-go solutions.
SimpleTexting may have the easiest signup and onboarding flow of any of the apps. Once you sign up with your email and provide some information about your business, you are given a free number and a big “Get Started” button. That’s it.
They then ask you what you plan to do with the account, and based on that info, create an onboarding tutorial that shows you the relevant places in the UI that you’ll need to visit. You have 50 credits and 14 days to test the service.
You can create campaigns to send out mass SMS to many contacts, and autoresponders to respond to any incoming texts to your free number. Accessing the API is easy once you figure out that it is under “Integrations” rather than its own tab. You have to contact support to request an API key, which is a bit of a pain, but that request can be made through an in-browser chat window, which makes things a little easier.
Pros
- Support is reported to be excellent
- Free trial available
- Easy to schedule and automate messages
Cons
- Different shortcodes for the US and Canada
- The pricing structure means it’s possible to run out of credits and drop messages
Reviews
“Its easy to use and they are ready to help 24/7! The software does everything you need and then some.”
“The app is a bit glitchy, and it does get pretty expensive when you have a decent amount of people on your list since you are charged based on sent messages. Eventually I may be priced out if I keep building.”
“SimpleTexting is simple to use and easy to implement in your marketing and communication toolbox. We use to communicate important upcoming events to our partners. I love that I can import lists and we don't have to use the 555888 sign up feature.”
Pricing
SimpleTexting pricing starts at $29/month for up to 500 messages, with each additional message costing $0.055. For $899/month you get up to 500,000 messages. Paying for plans annually saves you an additional 20%.
Best For
Those willing to pay for excellent customer service
Side By Side Comparison
Conclusion
When it comes to SMS API providers, its important to evaluate your own needs before deciding on an SMS service provider. Do you require dedicated customer support? How about bulk SMS or SMS marketing? Do you simply need to validate phone numbers, or will you need a dedicated message service or phone number lookup?
Once you’ve decided on the SMS functionality you need, look at the SMS API pricing to decide which API integration is right for you. Most of these services provide essentially the same feature set, so it often comes down to a case of pricing and customer support to make your decision.
FAQs
What is the best free SMS sending API?
If all you need is SMS verification, Telesign SMS Verify is a good free option. Other alternatives include D7 Verify, Clicksend, and Inteltech. You’ll get the best results, however, if you pay for a service. Twilio is the most robust solution out there, but Telnyx is probably the cheapest.
Which SMS gateway is best?
In terms of reliability, feature set, and support, Twilio far outstrips the competition. MessageBird runs a close second. However, if you want to pay a little less and can accept a few fewer features and perhaps less-than-stellar support, Plivo, Telnyx, and ClickSend are good choices too. For excellent service at a premium price, check out SimpleTexting.
What is the best SMS API for beginners?
Twilio has extensive documentation and a massive network of developers worldwide who are already using the product. It will be easy to find answers to your questions and quick to get up and running.
