Pick Attentive if you want a messaging-led platform for SMS, email, RCS and push, with AI journeys and the vendor's help moving your email across. Pick Klaviyo if you'd rather run email, SMS and customer service from one B2C CRM with a bigger integration list. Neither shows a clear overall winner, so put both in front of your own list before you sign.
Start with one decision: do you want a specialist messaging platform, or do you want your texts and emails to live inside your customer database? Answer that and the rest is detail. One of these two sells itself as an AI-powered SMS and email platform. The other now calls itself a B2C CRM, with service, analytics and a data platform sitting on top of the channels.
To keep things readable, I'll call the first one the messaging specialist and the second one the CRM from here on.
Messaging tool or customer database: the real fork
Plenty of write-ups still treat this pair as two SMS tools. That's out of date. Klaviyo has broadened into a CRM with a helpdesk, a Customer Hub and a data platform, so the question has moved from 'which SMS tool' to 'do I want my messaging inside my customer database'.
There's a second thing worth knowing before you read any comparison, including the vendors' own. The messaging specialist publishes its own head-to-head page against the CRM, links to it from its footer, and puts a quote from a customer who switched over on its home page. That's fair game in marketing, but it tells you who that page is written for. Read it as a pitch, not a referee's report.
So if you're on the CRM now and happy, a polished switch story shouldn't be the reason you move. And if you're new to both, the bigger decision is about shape: one tool for messages, or one system that holds the customer record and does messages too.
Side-by-side on the points that matter
| Area | Attentive | Klaviyo |
|---|---|---|
| Product framing | AI-powered SMS and email marketing platform | B2C CRM with marketing, service, analytics and a data platform |
| Channels | SMS, email, RCS for Business and push | Email, SMS, RCS, mobile app, WhatsApp and social |
| AI tools | AgentOS, AI Pro, AI Grow and AI Journeys, plus an MCP for AI assistants | K:AI Composer for flows and campaigns from a prompt, plus a Customer Agent for shoppers |
| Customer service | No helpdesk product on its home page | Service, Helpdesk and Customer Hub listed alongside marketing |
| Integrations | Says 100+ integrations | Says 400+ apps in its directory, plus developer APIs |
| International reach | Says it engages customers in 20+ countries | SMS in over 20 countries, with regional sites for the UK, DE, AU, SG, US, ES, FR and IT |
| Comparison stance | Runs its own head-to-head page and a switcher testimonial | Doesn't lead with a comparison against the other |
What each one does better
The messaging specialist's strengths
Its channel list is tight and focused: SMS, email, RCS for Business and push. On top sits a stack of AI products, which the vendor says includes AI Journeys, AI Pro and AI Grow, plus AgentOS. There's also an MCP connection, so an AI assistant can explore your data and update workflows. If your team already works with AI assistants day to day, that's a practical hook rather than a gimmick. It also has list growth units for building your subscriber base and says it reaches customers in 20+ countries.
The limit, going by its home page, is service: there's no helpdesk product listed. If you want support tickets and marketing in the same place, you'd need another tool alongside it.
The CRM's strengths
Breadth is the headline. It lists email, SMS, RCS, mobile app, WhatsApp and social as channels, and says its app directory holds 400+ apps, with developer APIs for anything else. Its K:AI Composer, the vendor says, builds flows and campaigns from a prompt, and the K:AI Customer Agent chats with shoppers around the clock.
It's also the one that's moved furthest from pure messaging. Service, a Helpdesk and a Customer Hub now sit alongside marketing. That's useful if you want one record per customer, but it's more platform to learn, and some pieces are still settling: Personalised Flows shows as beta on its SMS page.
On reach, the two are close. Both talk about 20+ countries, and the CRM runs regional sites for the UK, Germany, Australia, Singapore, the US, Spain, France and Italy.
My advice for each kind of store
Go with Attentive if messaging is the programme: you live in SMS and email, want AI journeys and sign-up units doing the heavy lifting, and like the idea of the vendor helping you move your email across. Go with Klaviyo if you want email, SMS and customer service under one roof, with your customer data at the centre and the bigger integration directory behind it. Neither shows a clear overall winner, so ask both for a demo using your own list and your own flows.
One more practical point. If you're on the CRM now and only shopping because of a switch story, write down the one thing that's broken first. If you can't name it, you probably don't need to move.
If the CRM is the one you're trying to leave, my roundup of alternatives to the CRM in this comparison covers more options, and the best SMS marketing software list is the place to start if texting is your main channel.
Want AI doing the heavy lifting in your marketing?
I build the systems that handle the boring 80 percent, so you get your week back. Done properly, with the human kept in.
Four more names for the shortlist
Omnisend
Best for: Ecommerce stores moving platforms: it's email and SMS software for online shops, and its home page pitches a team that moves your flows, lists and templates in 5 days.
Postscript
Best for: SMS-first retention for ecommerce, with SMS, RCS and email, an optional in-house strategy service and patented Onsite Opt-in the vendor says captures up to 3x more subscribers.
Mailchimp
Best for: Small teams wanting a familiar email and SMS tool with integrations, a marketing API and a transactional API. Its homepage offers a free 14-day trial.
Twilio
Best for: Developers who'd rather build messaging into their own app: an SMS API alongside WhatsApp, RCS, voice, email and phone numbers, not a marketing interface.
Do you make SMS or email marketing software? Tool makers can ask to be considered for a featured place on this page.
Want your tool on this list? Featured spots and reviews here are paid partnerships. Here's how to partner with me.
Frequently asked questions
Is Attentive or Klaviyo better for SMS?
Neither proves it's better at texting. The messaging specialist is built around SMS, email, RCS and push. The CRM covers SMS too, says it's available in over 20 countries, and adds WhatsApp and social. Pick on whether you want messaging alone or messaging inside a customer database.
Which of the two includes customer service tools?
The CRM. It lists Service, a Helpdesk and a Customer Hub alongside marketing. The messaging specialist's home page lists no helpdesk product, so you'd pair it with a separate support tool.
How many integrations does each one have?
The messaging specialist says 100+ integrations. The CRM says 400+ apps in its directory, plus developer APIs. Counts aren't everything, so check the two or three apps your store can't run without.
Can I use an AI assistant with either platform?
The messaging specialist offers an MCP connection so an AI assistant can explore data and update workflows. The CRM's K:AI Composer builds flows and campaigns from a prompt, and its Customer Agent talks to shoppers. They're different jobs: one lets your assistant work the platform, the other puts AI inside it.
Should I trust the vendor's own comparison page?
Read it, but read it as marketing. The messaging specialist wrote it and pairs it with a switcher testimonial, so it's built to persuade users of the CRM. Ask both for a demo with your own list instead.
