Kannel

Free plan APILinuxSelf-hosted

What Kannel is

Kannel is an open-source gateway for SMS messaging and WAP services. It connects HTTP-based services with SMS centers and offers an HTTP interface for sending messages and administering the gateway. It handles both SMS messages sent to phones and messages originating from phones, with documented connections to SMS centers over HTTP and SMPP. The project lists support for several SMS protocols, including CIMD, SMPP 3.4, UCP/EMI, SEMA SMS2000 OIS, and AT-protocol modems and phones.

For WAP services, Kannel converts WAP requests to HTTP, compresses WML pages for delivery to phones, and supports WAP Push SI and SL. Its guide also describes SSL for HTTP client and server communication and for SSL-enabled SMPP connections. Kannel is self-hosted and mainly developed on Linux; the project overview describes porting it to other Unix-like systems as fairly easy. The download page identifies version 1.4.5 as the stable release for production systems and version 1.5.0 as a development release. Wapit Ltd. founded the project in June 1999, and members of the Kannel Group coordinate it. The project points users to mailing lists for contact and development discussion.

Who it suits

Kannel suits teams that need to operate their own SMS or WAP gateway and connect HTTP-based services to SMS centers. It is aimed at users comfortable with Linux and self-hosted software, including those who need two-way SMS or WAP Push support.

What it does well

Free and open-source, with source and binary redistribution permitted under license conditions.
Provides an HTTP interface for administration and sending SMS.
Supports mobile-originated and mobile-terminated SMS.
Handles WAP requests, WML compression, and WAP Push SI and SL.
Documents SSL support for HTTP and SSL-enabled SMPP connections.

What to know first

Self-hosted deployment is required.
Main development is on Linux; other Unix-like systems may require porting.
SMSC drivers differ in supported features, and many checklist items are marked not tested.

Plans

Plan	Billed and limits	Price
Kannel	Open-source WAP and SMS gateway · self-hosted	Free

As kannel.org lists them, read 7 Oct 2026. The maker's own page has the final word.

Getting started

Visit the Kannel website.
Choose the stable 1.4.5 release for production systems or the 1.5.0 development release.
Set up a Linux environment for the self-hosted gateway.
Connect services and SMS centers through the documented HTTP or SMPP interfaces.
Use the project mailing lists for contact, development discussion, or patches.

Verdict

Choose Kannel if you need a free, self-hosted gateway for SMS and WAP services, with HTTP access and support for two-way messaging. It is a better fit for teams prepared to run gateway infrastructure on Linux; check the relevant SMSC driver capabilities for the features you need.

Questions

Is Kannel free?

Yes. The listed plan is free, and Kannel is open-source.

Which platforms does it support?

The listed platforms are API, Linux, and self-hosted. It is mainly developed on Linux, and the project overview says porting it to other Unix-like systems should be fairly easy.

Does Kannel support two-way SMS?

Yes. Its guide describes both mobile-originated and mobile-terminated SMS messages.

Which release is intended for production?

The download page identifies version 1.4.5 as the stable release intended for production systems. Version 1.5.0 is the development release.

What should I know about SMSC compatibility?

SMSC drivers do not all support the same features, and many entries in the guide’s compatibility checklist are marked not tested.

Who founded Kannel?

The project site says Wapit Ltd. founded Kannel in June 1999. Members of the Kannel Group coordinate the project.

Facts from Kannel's own pages

Download: The download page identifies version 1.4.5 as the stable release intended for production systems and version 1.5.0 as the development release. · kannel.org, 7 Oct 2026
Founded: 1999 · kannel.org, 28 Sept 2026
Free plan: Yes · kannel.org, 24 Sept 2026
Inbound webhooks: Yes · kannel.org, 24 Sept 2026
Integration: Kannel provides an HTTP interface for administration and sending SMS, and its guide documents HTTP and SMPP SMSC connections. · kannel.org, 7 Oct 2026
License: The Kannel Software License permits redistribution and modification of source and binary forms subject to its stated conditions. · kannel.org, 7 Oct 2026
Messaging: The user guide describes support for mobile-originated and mobile-terminated SMS messages. · kannel.org, 7 Oct 2026
Platform: Kannel is mainly developed on Linux and the overview says it should be fairly easy to port to other Unix-like systems. · kannel.org, 7 Oct 2026
Product: Kannel is an open-source WAP and SMS gateway for mobile internet connectivity, WAP Push, and SMS messaging. · kannel.org, 7 Oct 2026
Project history: The project site says Wapit Ltd. founded Kannel in June 1999 and that the project is coordinated by members of the Kannel Group. · kannel.com, 7 Oct 2026
Security: The user guide documents SSL support for HTTP client and server communication, and SSL-enabled SMPP connections. · kannel.org, 7 Oct 2026
SMSC limits: The user guide cautions that SMSC drivers do not all support the same features and that many checklist entries are marked not tested. · kannel.org, 7 Oct 2026
SMS protocols: The FAQ lists support for CIMD 1.3 and 2.0, SMPP 3.4, UCP/EMI 4.0, SEMA SMS2000 OIS, and AT-protocol modems and phones. · kannel.org, 7 Oct 2026
SMS use: It links HTTP-based services to SMS centers and provides a unified interface for sending SMS messages. · kannel.org, 7 Oct 2026
Support: The project directs users to its mailing lists for contact information and the developer mailing list for development discussion and patches. · kannel.com, 7 Oct 2026
Two-way SMS: Yes · kannel.org, 24 Sept 2026
WAP features: The gateway translates WAP requests to HTTP and compresses WML pages for delivery to phones. · kannel.org, 7 Oct 2026
WAP Push: The user guide lists support for WAP Push SI and SL. · kannel.org, 7 Oct 2026