Sinch
- Request
POST https://us.sms.api.sinch.com/xms/v1/{service_plan_id}/batches- Authentication
- Bearer API token (Authorization header)
- Minimum fields
- from, to (array), body
Best SMS API providers for US developers
Sinch and Twilio score highest on our gateway fit score, 10 out of 10: their documentation states all 8 things a developer checks, from SDKs and delivery webhooks to a sandbox and a published uptime SLA. Telnyx is next at 9.38. At 10,000 texts a month, messages cost $83 on Twilio against $35 on Bird (formerly MessageBird), the lowest published rate here.
Alain Grossbard OAM, with Justin Grossbard Updated How we rate Reader supported, we may earn a commission Reader supported. We may earn a commission when you sign up through a link on this page, and it never changes a score. How we make money.
The 15 SMS APIs ranked by gateway fit
Showing all 15 SMS APIs.
Long-code message rate, cheapest published sending number and captured carrier fees. Registration fees excluded.
| # | SMS API | Gateway fit | SDK languages | US numbers | Sandbox | Uptime SLA | Month at 10,000 |
|---|---|---|---|---|---|---|---|
| 1 | SinchOverall score 8.00 | 10.00 | Node.js, Java, .NET, Python | 10DLC, Toll-free, Short code | Yes | Published | $79 not in it: carrier fees (billed on top, amount not published) |
| 2 | TwilioOverall score 7.42 | 10.00 | Node.js, Python, C#, Java, Go, PHP, Ruby | 10DLC, Toll-free, Short code | Yes | Published | $119.15 to $134.15 |
| 3 | TelnyxOverall score 8.08 | 9.38 | Python, JavaScript/Node.js, Ruby, Go, Java, C#/.NET, PHP | 10DLC, Toll-free, Short code | Partly | Published | $40 not in it: carrier fees (passed through at cost) and number rental (not published) |
| 4 | InfobipOverall score 7.25 | 8.75 | PHP, Java, Python, C# | 10DLC, Toll-free, Short code | Partly | Published | $116.80 to $131.80 not in it: number rental (not published) |
| 5 | PlivoOverall score 6.25$1,000 a month minimum (Enterprise plan) | 8.75 | Python, Node.js, Ruby, PHP, Java, .NET, Go | 10DLC, Toll-free, Short code | Not found | Published | $112.50 to $127.50 |
| 6 | ClickSendOverall score 7.58 | 8.13 | PHP, C#, Node.JS, Python, Perl, Ruby, Go, ObjectiveC, Swift | 10DLC, Toll-free, Short code | Partly | Published | $253.57 |
| 7 | BandwidthOverall score 6.83 | 7.50 | PHP, C#, Node.js, Java, Ruby, Python | 10DLC, Toll-free, Short code | Not found | Partly | $95 to $110 not in it: number rental (not published) |
| 8 | Bird (formerly MessageBird)Overall score 5.67 | 6.25 | TypeScript, Python, Go, PHP | 10DLC, Toll-free, Short code | Not found | Not published | $71 to $86 |
| 9 | ClickatellOverall score 5.83 | 6.25 | Not captured | 10DLC, Short code | Yes | Published | $75.10 not in it: carrier fees (not captured) and number rental (not published) |
| 10 | MessenteOverall score 5.58 | 6.25 | Python, Node, PHP, Java, Ruby, .NET | Not stated | Partly | Not published | Not priced in US dollars |
| 11 | SMSGlobalOverall score 6.67 | 5.63 | PHP, .Net, Node | 10DLC | Yes | Not published | $190 not in it: carrier fees (not captured) and number rental (not published) |
| 12 | BulkSMSOverall score 5.17 | 3.13 | Not captured | 10DLC | Not found | Not published | $335 not in it: carrier fees (not captured) and number rental (not published) |
| Kudosity (formerly BurstSMS)Overall score 8.17 | Not assessedofficial sdks, sandbox, test mode or test credentials not read | Not captured | 10DLC, Toll-free, Short code | Not read | Published | $155 | |
| NotifyreOverall score 6.50 | Not assessedsandbox, test mode or test credentials not read | .NET, Node.js | 10DLC | Not read | Published | $216.40 | |
| VonageOverall score 6.58 | Not assessedsandbox, test mode or test credentials not read | Ruby, PHP, Python, .NET, Node.js, Java | 10DLC, Toll-free, Short code | Not read | Published | $112.05 to $137.05 |
Kudosity (formerly BurstSMS), Notifyre, Vonage are not assessed: a criterion was not read from their documentation, and a provider is never scored on part of the method. The 8 criteria and their scoring are on how we rate SMS providers. Ranked by price instead of developer fit, the SMS APIs are compared on the cheapest SMS APIs. A business with no developer sends from a web app instead, and those services are compared on mass texting services.
The send request on each SMS API, side by side
What one text takes on each provider: the endpoint, how the request authenticates, and the fields a minimal send needs, quoted from each provider's own API reference on 21 September 2026.
Twilio
- Request
POST https://api.twilio.com/2010-04-01/Accounts/{AccountSid}/Messages.json- Authentication
- HTTP Basic (Account SID as username, Auth Token as password)
- Minimum fields
- To, From (or MessagingServiceSid), Body (or MediaUrl or ContentSid)
Telnyx
- Request
POST https://api.telnyx.com/v2/messages- Authentication
- Bearer API key (Authorization header)
- Minimum fields
- from, to, text (or media_urls)
Infobip
- Request
POST https://api.infobip.com/sms/3/messages (tutorial host; accounts also have a personal base URL)- Authentication
- API key header: Authorization: App {API_KEY}
- Minimum fields
- messages[].sender, messages[].destinations[].to, messages[].content.text
Plivo
- Request
POST https://api.plivo.com/v1/Account/{auth_id}/Message/- Authentication
- HTTP Basic (Auth ID and Auth Token)
- Minimum fields
- src (or powerpack_uuid), dst, text (listed without a required marker in the page text read)
ClickSend
- Request
POST https://rest.clicksend.com/v3/sms/send- Authentication
- HTTP Basic (API username and API key)
- Minimum fields
- messages[].body, messages[].to (or messages[].list_id)
Bandwidth
- Request
POST https://messaging.bandwidth.com/api/v2/users/{accountId}/messages- Authentication
- HTTP Basic (username and password)
- Minimum fields
- from, to (array), text, applicationId
Bird (formerly MessageBird)
- Request
POST https://{region}.platform.bird.com/v1/sms/messages (region us1 or eu1, carried in the API key prefix)- Authentication
- Bearer API key (Authorization header)
- Minimum fields
- to, from, text, category (transactional, marketing, authentication or service)
Clickatell
- Request
POST https://platform.clickatell.com/v1/message- Authentication
- API key in the Authorization header (no scheme prefix)
- Minimum fields
- messages[] (1 to 100 items), channel, to, content
Messente
- Request
POST https://api.messente.com/v1/omnimessage- Authentication
- HTTP Basic
- Minimum fields
- Not captured: the reference renders its schema in the browser
SMSGlobal
- Request
POST https://api.smsglobal.com/v2/sms- Authentication
- MAC header (API key id, timestamp, nonce, HMAC hash)
- Minimum fields
- Not published on the page read
BulkSMS
- Request
POST https://api.bulksms.com/v1/messages- Authentication
- HTTP Basic with an API token (token ID as username, token secret as password)
- Minimum fields
- to, body
Kudosity (formerly BurstSMS)
- Request
POST https://api.transmitsms.com/send-sms.json- Authentication
- HTTP Basic: base64 of api_key:api_secret
- Minimum fields
- message, to (up to 500 comma-separated numbers)
Notifyre
The send request was not captured from this provider's documentation.
Vonage
- Request
POST https://rest.nexmo.com/sms/:format- Authentication
- HTTP Basic header: Base64 of API key and secret joined by a colon
- Minimum fields
- to, text, and one more required field whose name the page read did not show
SMS pumping and OTP verification
SMS pumping is fraud in which bots trigger one-time passcode or other texts to numbers the fraudster profits from. Vonage calls it Artificially Inflated Traffic and sells Fraud Defender against it. Of the 15 SMS APIs here, 9 publish protection in their own words: Twilio's Fraud Guard is on by default but applies to Twilio Verify only, and Plivo's Fraud Shield is stated at no extra cost. Twilio Verify costs $0.05 per successful verification plus $0.0083 per SMS, Telnyx $0.03 plus SMS pricing, and Vonage Verify $0.06084 per successful verification plus messaging. Plivo charges no verification fee, only the message rate, on its Enterprise plan, which starts at $1,000 a month, and Bird charges no verification fee either. All read on September 28, 2026.
What an SMS API is
An SMS API is the web interface a provider publishes for software to send text messages. In the documentation of 14 of the 15 providers this page ranks, sending one text is one HTTP POST request to the provider's endpoint, carrying the recipient, the sender and the message text, with delivery receipts returning to your server by webhook. We rank the providers with a gateway fit score built from eight criteria of equal weight read from each provider's developer documentation, and the full method names each criterion. To connect an SMS API to the apps your business already runs, start with our integrations guide.
How you choose an SMS API
Check the send request and its authentication
Read the send request in each provider's API reference and match its authentication to what your stack holds. In the documentation of 14 of the 15 providers ranked here, read on 21 September 2026, sending one text is one HTTP POST request. Twilio uses HTTP Basic with its Account SID and Auth Token, Plivo with its Auth ID and Auth Token, and Bandwidth with a username and password. Sinch and Telnyx use a Bearer token, and Infobip puts an API key in the Authorization header with the prefix "App".
Price your monthly volume
Price your monthly volume before you commit, with every fee included. At 10,000 texts a month, message charges run from $35 on Bird and $40 on Telnyx to $83 on Twilio and $86 on Vonage, from each provider's published US rate. Add the sending number and the published carrier fees, and Twilio comes to $119.15 to $134.15 a month and Plivo to $112.50 to $127.50, with a $1,000 a month minimum (Enterprise plan). The cheapest ranking sorts the SMS APIs by price alone.
Match the number type to your throughput
Match the number type to the volume you send, because throughput differs by type. Twilio publishes up to 225 messages per second per campaign on 10DLC and 100 or more on a short code. Sinch publishes up to 75 per second on 10DLC with carrier approval, 500 on a short code and 10 on a toll-free number. Telnyx publishes 20 per second per toll-free number and 1,000 per short code.
Test on a trial before you build
Test on a trial before you write any code. Plivo gives $10 in free credits with no credit card, valid for the first three weeks, and Infobip runs a 60-day free trial. Twilio's free trial includes 100 SMS messages to verified recipients for 30 days with no credit card, read September 9, 2026. Vonage gives free credit with no card, amount not published. Bird gives a free test API key only, with no free SMS allowance, and the Bandwidth self-serve trial covers voice only, not messaging.
Questions people ask about SMS APIs
Which SMS API is the best?
The gateway fit score ranks Sinch and Twilio highest at 10 out of 10, as of 21 September 2026. The score measures eight criteria of equal weight read from each provider's developer documentation, including official SDKs, delivery receipts by webhook, a published uptime SLA and US 10DLC, toll-free and short code numbers. Telnyx follows at 9.38.
Is there a free SMS API?
Every provider on this page charges per message, so a free SMS API in the sense of free sending does not appear here. The trials differ. Twilio offers a free trial account with no credit card, Plivo gives $10 in free credits valid for the first three weeks, Infobip runs a 60-day free trial, and Sinch and Vonage give trial credit on sign-up with no card.
Is Twilio SMS API free?
No. Twilio charges per message, and at 10,000 texts a month the message charges come to $83 from Twilio's published US rate. With the sending number and the published carrier fees added, the monthly cost is $119.15 to $134.15. Twilio's free trial includes 100 SMS messages to verified recipients for 30 days with no credit card, read September 9, 2026.
How to send 1000 SMS at once?
You send to many numbers in one request where the API supports it. Kudosity's (formerly BurstSMS) send endpoint takes up to 500 comma-separated numbers in one request. Clickatell's message request takes 1 to 100 messages. Sinch and Bandwidth take the recipients as an array.
Is B2B texting legal?
A B2B label does not create an exemption. When a marketing text goes to a mobile number by a covered autodialed method, 47 CFR 64.1200(a)(2), checked October 4, 2026, requires prior express written consent, subject to exceptions. Opt-outs must be honored. Number registration is a separate carrier process and does not establish consent. See our SMS compliance guide.