Communication
Services to communicate with others
APIs to send e-mail, text messages, faxes, chat and push notifications from your own software, for example sign-up mails, alerts to your phone or messages to a team channel. Most have a free plan with a monthly limit; webhooks for Slack and Discord are free to use.
Brevo (Sendinblue) email API
Brevo (formerly Sendinblue) offers an API to send transactional e-mail from your application, such as order confirmations and password resets, plus SMS and WhatsApp messages. Use templates with variables, track opens, clicks and ...
Discord webhooks
Discord webhooks are the easiest way to post messages to a Discord channel from your own software: create a webhook in the channel settings and send a POST request with your message to its URL. Messages can contain text, a custom ...
InterFax
The InterFAX web service lets developers send and receive faxes from their own software, in any environment that can call SOAP or REST, such as .NET, Java, PHP or Python. Send documents in many formats (PDF, Word, HTML and more) ...
Mailtrap
Mailtrap is an e-mail platform for developers with two parts. Email Sending is an e-mail API and SMTP service for transactional and bulk e-mails, with delivery tracking and analytics. Email Testing is a sandbox inbox that catches ...
Noteshred
Create a note, assign it a password and then select how and when you would like the note to shred itself. Attach a file to be encrypted if you wish. The note has a unique URL that you can send to a recipient along with a password ...
ntfy
ntfy (pronounced 'notify') lets you send push notifications to your phone or desktop with a simple HTTP request: PUT or POST a message to a topic URL such as ntfy.sh/mytopic, and every device subscribed to that topic gets it. ...
Phaxio
Phaxio lets developers send and receive faxes with a simple REST API. Send a document (PDF, Word, HTML and more) or a URL to one or more fax numbers, and receive incoming faxes as PDF through callbacks to your server; status ...
QConf Conference Calling API
QConf's API lets you add conference calling to your service, site or app. Your users can schedule, update, reschedule or cancel conference calls without software or hardware; participants call a local access number and enter a ...
Resend
Resend is an e-mail API for developers: send transactional e-mails from your own domain with a simple REST call, write templates in React or HTML, and track deliveries, opens, clicks and bounces through webhooks. SDKs are ...
Seanox XMEX
XML-Micro-Exchange is a volatile NoSQL stateless micro datasource for the Internet. It is designed for easy communication and data exchange of web-applications and for IoT or for other Internet-based modules and components. The ...
Slack incoming webhooks
Incoming webhooks are the easiest way to post messages to a Slack channel from your own software: create a webhook in a Slack app and send a POST request with a JSON message to its URL. Messages can use formatting, links, and ...
Telegram Bot API
The Telegram Bot API lets you build bots for the Telegram messenger. A bot can send and receive messages, photos, files and polls, show buttons and custom keyboards, work in groups and channels, and accept payments. You get a bot ...
TheTexting
TheTexting.com offers SMS API services and SMS Gateway services for OTP text messages, notification texts, or even preferred for text marketing via own Text API based solution.
Compare the email, SMS and messaging APIs
| Service | API key | Formats | Free use |
|---|---|---|---|
| Brevo (Sendinblue) email API | – | JSON | The free plan allows 300 e-mails per day; paid plans remove that limit. |
| Discord webhooks | – | JSON | Free; for two-way interaction use the full Discord bot API. |
| InterFax | Needed, free | XML | Paid per page, with a free developer account for testing. |
| Mailtrap | – | JSON | Free plan with 4,000 sent e-mails per month (at most 150 per day, one domain) and a testing sandbox with 50 e-mails per month; paid plans for more. |
| Noteshred | – | JSON | – |
| ntfy | – | – | Free on ntfy.sh, and open source so you can host it yourself. |
| Phaxio | – | JSON | Paid per page, with a free test mode. |
| QConf Conference Calling API | Needed | – | – |
| Resend | – | JSON | The free plan allows 3,000 e-mails per month (at most 100 per day) and up to 3 domains; paid plans offer more. |
| Seanox XMEX | – | – | – |
| Slack incoming webhooks | – | JSON | Free, also on free Slack workspaces. |
| Telegram Bot API | – | JSON | Free. |
| TheTexting | – | JSON | – |
Questions
Are these email, SMS and messaging APIs really free?
The services here can be used without paying, at least on a free plan or free tier, often with limits such as a number of requests per day or non-commercial use only. The table above quotes what each service says about its free use; check the provider's own terms before you rely on it.
How up to date is this list?
The address of every service is checked about once a week, and services that stop working or stop being free are removed. This list last changed on October 31st, 2026.