Free SMS APIs

Check out this list of Free (and Freemium) SMS APIs.
List of Top SMS APIs to Send Text Messages (Updated for 2019)RapidAPI blog
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Free SMS APIs

Best Free SMS APIs and SMS Gateways

APIs in this collection are either Free or have a freemium tier monetization model.

Twilio API Pricing

Twilio has a pay-as-you-go model, but offers a free trial credit to start with.

Telynx API Pricing

Telnyx offers free inbound SMS texts, but charges $0.0045 Per Outbound Message.

Plivo API Pricing

Plivo is another SMS service that has pay as you go pricing, but offers free trial credit.

MessageBird SMS Pricing

Messagebird, like Telynx, offers free inbound SMS texts, but charges for outbound SMS messages.

ClickSend SMS Pricing

ClickSend inbound SMS messages are free, but outbound SMS messages depend on volume.

Estimated MessagePrice/SMS
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Under 2k$0.0095
2k or more$0.0088
10k or more$0.0073
100k or more$0.0067
Over 200kCustom Pricing

What is an SMS Gateway?

An SMS gateway can be set up to handle the connections to the SMSCs. Now the SMS text messaging application only needs to know how to connect to the SMS gateway. To support more SMSCs, you just need to modify the settings of the SMS gateway. No change to the source code of the SMS text messaging application is required. The use of an SMS gateway can greatly shorten the SMS text messaging application's development time. Source: developershome

Install SDK for (Node.js)Unirest

OAuth2 Authentication
Client ID
Client Secret
OAuth2 Authentication