The best free and open source SMS marketing software
There is no mature open source SMS marketing platform with a hosted free tier, so most free options are really free plans that bill per message. We ranked the five cheapest credible ways to start, plus the one genuinely open source route you can host yourself.
Reviewed by M. HALLORAN·Updated APRIL 2026·How we vet
Tools compared5
Criteria weighted5
Last reviewedJune 2026
Paid placements0
How we ranked the field
Scored on our five core criteria, then reweighted for the lowest standing cost: free to start, cheap per message, and a tool you can run without a budget. Open source and data control break ties. See the full rubric →
Free to start35%
Cost per message25%
Ease of use20%
Features12%
Data control8%
01
RANK
★ Editor’s Choice
Klaviyo SMS
Best for a free plan with SMS
Klaviyo has the most generous starting point: its free plan keeps 150 SMS credits a month at no cost alongside email, with paid email and SMS plans from $35 a month once you outgrow it. It is a full ecommerce marketing suite, not a bare texting tool, so you get more than you pay for to begin.
A free plan to start and prepaid SMS credits that never expire, at roughly a cent per US message. There is no standing free SMS allowance, but the base cost is zero and you only pay for what you actually send, which suits a low volume sender.
Not free to run, but the Launch plan is among the cheapest real plans at $25 a month including a $5 telecom fee, with a free trial to test first. It is simple to learn, which matters when no one is there to administer it for you.
No monthly fee at all, only the credits you spend at about five cents a US text, which fits very low or irregular volume. A bring your own carrier option drops that to about a cent if you wire up a Twilio or Vonage number yourself.
The only genuinely open source pick, free under the GPL and yours to host, with SMS sent through a bundled Twilio gateway. You trade simplicity for control: it needs a server, a database and someone comfortable maintaining both, but the software itself costs nothing.