Best SMS API providers for US developers

Compare 15 SMS APIs, 12 ranked by gateway fit

Kudosity (formerly BurstSMS), Notifyre, Vonageare not assessed because 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.

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.

Free trial terms for each SMS API

The table below answers one question for the 15 SMS APIs compared here. Can you send a real text from a new account without paying? 10 do, 4 do not, and 1 gives free credit but its pricing page puts SMS on a paid plan. Each row gives what the trial includes, what it cannot do, and a link to the provider's own page, read on 22 October 2026. Some trials give a dollar credit, some a number of free messages, some a number of days. The limits providers state include sending only to phone numbers you have verified, a notice or prefix added to each trial text, and a daily cap. Twilio's trial guide says A2P 10DLC registration needs a paid account. After the trial, compare price on the cheapest SMS APIs.

Transactional and notification sends

The table below lists the 15 SMS APIs this page compares and shows, for each, whether its own SMS product page names three kinds of send: verification codes (OTP or 2FA), notifications, alerts or updates, and sends it calls "transactional". Of the 15, 9 name verification codes, 14 name notifications, alerts or updates, and 6 use the word "transactional"; these counts overlap. Filter the table by message type to find the APIs that name the sends you run. Each row quotes the words the provider's own page uses, with a link and a read date. We read the product pages on 21 October 2026; where a product page named no message class, the row quotes an earlier dated page from the same provider's site and says so.

A transactional or informational text tells a customer something about an account, an order, an appointment or a login. A marketing text includes an advertisement or constitutes telemarketing. The FCC rule at 47 CFR 64.1200(a)(2) requires prior express written consent for a text that includes an advertisement or constitutes telemarketing sent with an autodialer. The FCC's consumer guide says commercial texts require written consent, and that for informational texts consent may be oral. These distinctions sit inside the wider SMS compliance rules for US senders.

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 compares, 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 12 providers with a gateway fit score built from 8 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 compared 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 commit to an integration. Bandwidth Build includes 30 days of Messaging API access and 3,000 credits shared with Voice API usage, with one US number and no credit card required, read 22 October 2026. Trial texts go only to your verified mobile in the US or Canada, with a trial prefix and a limit of 200 a day. MMS is excluded.

Plivo gives $10 in trial credit for three weeks, but its SMS pricing places SMS on the Enterprise plan with a $1,000 monthly minimum, read 22 September 2026. Trial credit does not establish access to SMS.

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 9 September 2026. Check the trial terms for each SMS API before you build.

Questions people ask about SMS APIs