Congratulations on the promotion, by the way, in case nobody actually said it out loud when they handed you three new channels to own.

One month you were the person who owned email. Now, you're in charge of the entire customer journey, which is a wildly different job that just happens to still have your old title stapled to your Slack profile.

You didn't fall out of love with your email service provider (ESP). It's still doing exactly what it's always done, sending the flows you built, landing right where it's supposed to land. But, now you need something that can also carry push, in-app messages, SMS and RCS, and whatever cross-channel journey shows up on the roadmap next quarter.

If that gap makes you feel a little disloyal, like you're about to break up with the tool you once defended in every vendor comparison and every internal Slack argument, you're not imagining it, and you're not the only one. This is what happens when a job outgrows the stack it was hired into. So here's a practical, judgment-free look at what actually changed, and what to do about it.

Jobs grow (and tools don't always keep up)

Klaviyo and Customer.io both started as email-first tools, and for a long time that was the whole story. Klaviyo's own pricing page still opens with “Start Free with Email & SMS,” and its free plan reflects that history: 250 profiles, 500 emails a month, $5 of SMS credits. But both platforms have spent the last couple of years building out from that base, and it's worth being accurate about how far that's come rather than repeating the old story because it's convenient.

Klaviyo now ships mobile push notifications and in-app messaging free with every plan, has RCS in private beta, and has added WhatsApp, all coordinated through what it now calls its omnichannel layer. Customer.io includes unlimited push and in-app messaging starting on its entry-level Essentials plan at $100/month, not gated behind its $1,000/month Premium tier the way it's tempting to assume.

What still doesn't travel with either of them: web push and Live Activities. Neither platform lists those channels anywhere in its current lineup, and that's the real, checkable gap for a role that now owns the full mobile-and-web customer engagement surface. “They only do email” isn't the accurate version of this story anymore.

None of this means either platform is weak. Customer.io says it's trusted by 9,000+ brands, and that's earned. Both are mature, credible platforms doing real work for the teams that chose them. The gap that actually matters when your job expands isn't which channels exist somewhere in the product; it's which channels are core to the platform's architecture and unified user model versus stitched on next to a system built around a single-channel profile. In other words, you outgrew your tools because your job got broader, not because either tool stood still.

Klaviyo vs. Customer.io vs. OneSignal: channels and pricing side by side

Here's how the three platforms line up on the two things that matter most when your scope expands: which channels are native, and where the actual gaps sit.

Full detail on how OneSignal's own channel set and pricing compare is on our OneSignal vs. Customer.io comparison page.

Klaviyo: excellent for eCommerce messaging, still missing web push and Live Activities

Klaviyo is genuinely strong at what it does, and it's worth naming that clearly before looking at where the real gap sits today.

What Klaviyo does well:

• eCommerce-native email and SMS. Deep integrations with online stores and purchase behavior make it a natural fit for retention flows.
• Mobile push and in-app messaging, included free. Every Klaviyo plan now ships unlimited push sends and in-app messaging, plus RCS in private beta and WhatsApp, coordinated through its omnichannel campaign builder.
• A mature, trusted messaging engine that thousands of eCommerce brands rely on daily.

Where it stops for a customer-engagement-scope role:

• Web push and Live Activities aren't part of the product. Neither channel appears anywhere in Klaviyo's lineup, so a team that needs to reach people through the browser or a lock screen still needs a separate tool, regardless of tier.
• The free-plan limits (250 profiles, 500 emails/month, $5 of SMS) still signal the design center: a tool sized for a growing eCommerce list, not a high-volume, cross-channel mobile-and-web program.

Klaviyo alternatives such as OneSignal fit better once the job stops being about email and becomes about the mobile app itself, and that's less a feature gap than a difference in what each platform was actually built to do. Klaviyo grew up as an eCommerce email tool for Shopify-style stores, so channels like push, in-app, and RCS arrived later as extensions of that core.

OneSignal grew up building push infrastructure for mobile apps, so web push, in-app, and Live Activities were never bolt-ons. They're the reason the platform exists in the first place. That's why the gaps show up where they do: web push and Live Activities aren't missing from Klaviyo by accident, they're missing because the product was never designed around a mobile app as the center of gravity. A mobile-first lifecycle role is better served by a platform built for that job from day one.

Customer.io: flexible workflows, with real limits on scale and support at the entry tier

Customer.io earns its reputation among engineering-minded lifecycle teams, and its strengths are real and specific.

Customer.io is strong for teams needing highly flexible, event-driven segmentation and workflow logic, especially those with complex data models. If your product emits a rich stream of custom events and you want to branch on them in intricate ways, this is where Customer.io shines. Push and in-app messaging are included starting at its entry Essentials plan, $100/month for 5,000 profiles and 1 million emails/month, so, credit where it's due, omnichannel isn't gated behind a higher tier the way it can look at first glance.

What the jump from $100 to $1,000 for Premium actually buys you is uncapped profile and email volume, more custom object types, elevated AI agent limits, HIPAA compliance, premium data integrations, and premium support: real things, just not multichannel access itself. Both Essentials and Premium list unlimited API calls on Customer.io's own pricing page, so that's not a lower-tier constraint either. The catch is more about scale: a growing cross-channel program will likely outgrow the Essentials caps and land you in custom Premium pricing sooner than you'd expect, which is worth budgeting for even if it isn't a “channels behind a paywall” story.

On channels, Customer.io still doesn't offer web push or Live Activities at any tier, which matters if your job now owns the full mobile-and-web surface.

And again, this is a mature platform, as its 9,000+ brands standing makes clear.

When is Customer.io still the right call? When you're running complex, engineering-supported product-led-growth journeys built on heavy custom event data, and you have the technical resources to feed and maintain them. In that scenario, its workflow logic is a genuine asset. For teams weighing Customer.io alternatives because they're bumping into the Essentials caps or need web push and Live Activities, the calculation looks different.

Where a full customer engagement platform like OneSignal fits

Once your role's scope has genuinely outgrown an email-first ESP, OneSignal is the logical next step. This isn't a rip-everything-out pitch. It's simply the platform built for the wider channel set your new job now owns.

As the comparison table lays out, OneSignal covers the full channel set explicitly, from mobile and web push through in-app messaging, email, and SMS/RCS to Live Activities, plus Journeys for building automated, omnichannel customer paths. Multi-channel is the starting point here, not an upsell.

The plan structure reflects that, from a Free Plan through the Growth Plan at $19 per month to custom-priced Professional and Enterprise tiers (see the comparison table above). Set that $19 entry point next to what it costs to unlock uncapped volume and premium support on Customer.io, and the difference in how each platform prices growth becomes easier to see.

SMS/RCS on OneSignal is set up directly with the OneSignal team regardless of plan, so pricing scales with your actual usage instead of forcing a tier jump to unlock the channel.

This isn't only a claim we're making in the abstract: OneSignal serves more than 2 million users today, and mobile-first teams keep landing here specifically because push, web push, in-app, email, SMS/RCS, and Live Activities are core parts of one platform rather than separate purchases. If you want the full picture, our customer engagement platform overview lays out how the channels and Journeys work together.

Deciding whether to switch or simply add a channel

Before you touch anything, get clear on whether the job needs a new platform or just a new channel. Both are valid answers, and the right one depends on your stack, not on how you feel about your current tool.

Questions to ask before you touch your stack

Our guide on choosing a platform that fits your actual tech stack frames the evaluation well. Apply each question to your Klaviyo or Customer.io reality:

• What does your data infrastructure look like? If you already route events through Segment, Amplitude, or a similar CDP, a new engagement platform should slot in without a rebuild.
• How much engineering time can you commit? Customer.io's workflow depth assumes engineering support. Be honest about whether you have it.
• What channels do you actually use today, versus own on paper? If your title says lifecycle but you're still only sending email, the gap is your roadmap.
• What's your real budget, including implementation time? Count the hours, not just the license fee. A cheaper plan that takes a quarter to stand up isn't cheaper.

There's also a low-risk answer people forget to consider. You don't always have to replace your email tool to gain new channels. OneSignal's Free Plan can run alongside an existing ESP to cover the channels it doesn't, so you can add push or in-app messaging without a forced rip-and-replace. Test the channels your new role owns before you commit to a full migration.

How to build the case without burning the relationship with your current ESP

When you do decide to make the case internally, the phased approach in our “How to Tell Your CMO” article keeps it professional and blame-free:

• Assess the current tool objectively against real pain points, not vibes. Name the specific channels and volumes it can't cover.
• Build a data-driven business case that quantifies costs and ROI across hard benefits (license and message costs) and soft benefits (team hours, faster launches).
• Present a well-researched comparison, not a single-vendor pitch. Show the options you evaluated and why one fits.
• De-risk the transition with a phased migration plan and buy-in from IT, product, and data teams before anyone signs anything.

Keep the emotional throughline from earlier in mind. This is a scope decision, not a betrayal of the tool that got you here. Focus on the part you can actually control, which channels the job needs, not how loyal you feel to the logo on your login screen.

Here's a clean litmus test to run on yourself: does the job now require channels your current plan doesn't offer, at a price jump that's hard to justify to a CMO? If yes, you're not being disloyal by looking. You're doing your job.

You don't have to rip anything out to find out. Spin up OneSignal's Free Plan, point it at the one channel your current tool can't touch, and see what the rest of your job actually looks like when the stack finally matches it.

Frequently asked questions