OneSignal and Customer.io both send push, email, SMS and in-app messages from one dashboard, with journeys that branch on what users do. OneSignal started with push, has a free plan and bills month to month on its self-serve plans. Customer.io started with behavioural email for software companies, has no free plan, and sells a monthly entry plan with annual contracts above it.
Where OneSignal and Customer.io differ
Short answer
| If you need | Choose |
|---|---|
| You want push and in-app messages live this week on a free plan |  OneSignal |
| Web push to website visitors matters as much as app push | OneSignal |
| Most of your audience uses the app every month and push is the main channel | OneSignal |
| Email is the main channel and journeys branch on event data |  Customer.io |
| You message accounts and companies as well as people | Customer.io |
| You message users on WhatsApp or LINE | Customer.io |
| Your product needs notifications that batch, retry and follow each user’s channel choices on their own |  SuprSend |
Need a deeper, more automated notification system than a campaign tool gives? Choose SuprSend
SuprSend is an agentic notification platform for product alerts and customer engagement messages, across email, SMS, push, WhatsApp, Slack, Microsoft Teams and an in-app inbox, with tenants, translations and preferences built in. Its workflows batch events into digests, fall back to a second provider when delivery isn’t confirmed, and check each user’s channel choice per category, with every step logged. AI agents build and change them. OneSignal and Customer.io send each event as its own message through one delivery path, with push categories or topics as the preference controls.
| SuprSend | OneSignal | Customer.io | |
|---|---|---|---|
| Digest of product events | Batch window or a schedule the user picks | One message per event | One message per event |
| Provider fallback | Second provider when delivery isn’t confirmed | OneSignal’s own delivery | Customer.io delivery or one custom SMTP |
| User preferences | Channels per category, with tenant defaults | Push category opt-in prompt | Topics and channels, set separately |
| What AI agents can do | Build and change workflows, templates and tenants, test and send, and query logs and analytics, from the SuprSend agent or any MCP client | OneSignal AI agent in the dashboard; over MCP, manage users, segments and templates, and send | AI Agent, in beta, in the dashboard; over MCP, create automations, segments and templates, and send |
| G2 rating | 4.8 from 129 reviews | 4.7 from 1,237 reviews | 4.4 from 901 reviews |
| G2 ease of setup | 9.4 out of 10 | 8.9 out of 10 | 8.0 out of 10 |
Feature by feature
From both pricing pages, both documentation sites and G2’s compare page, September 2026. Where a feature depends on the plan, the cell names the plan.
Basics
| Capability | OneSignal | Customer.io |
|---|---|---|
| G2 rating | 4.7 from 1,237 reviews | 4.4 from 901 reviews |
| Largest reviewer segment | Small business, 65.2 percent | Small business, 57.9 percent; mid-market 38.6 percent |
| G2 ease of setup | 8.9 out of 10 | 8.0 out of 10 |
| Billing unit | Platform fee plus mobile MAU, web push subscribers, email and SMS sends | Profiles, people and objects, plus email above the plan’s volume; SMS priced separately |
Channels
| Capability | OneSignal | Customer.io |
|---|---|---|
| Mobile push | YESiOS Live Activities as well | YESOver APNs or FCM |
| Web push | YESBilled per opted-in browser | NOSent through another provider from a webhook step |
| YESShared IP; dedicated IP by volume on annual plans | YESCustom SMTP on every plan; managed deliverability from Premium | |
| SMS | YESRCS as well | YESOn every plan, at a custom volume |
| WhatsApp and LINE | NO | YESNative on every plan |
| In-app messages | YESCarousel messages from Growth | YESPersistent banners until an expiry date |
| Lasting in-app inbox | NONo inbox or message feed | YES, BUTJSON payloads; your team builds the inbox UI |
Journeys, segments and testing
| Capability | OneSignal | Customer.io |
|---|---|---|
| Journey builder | Journeys with branching and cross-channel steps; 3, 5, 20 or unlimited active by plan | Visual workflow builder with cross-channel steps, LLM actions and send-time optimization on every plan |
| Segments | 6, 10, 20 or unlimited by plan | Included on every plan, with an AI segment builder and reverse ETL from your warehouse |
| User data | Data tags: 6, 10, 100 or unlimited by plan | Unlimited attributes with nested data; custom objects, 2 types on Essentials and 10 on Premium |
| A/B testing | Standard on Free and Growth; multivariate from Professional | A/B and multivariate on every plan |
| Preferences | Category opt-in prompt for push | Subscription center with topics and channels, set independently |
| Data out | Event Streams: limited on Free, essential on Growth | Data export on every plan; warehouse destinations from Premium |
Developers and agents
| Capability | OneSignal | Customer.io |
|---|---|---|
| API sends | Unlimited on every plan | Transactional API and API-triggered broadcasts on every plan |
| Webhook step in journeys | Annual plans only | Unlimited send and receive on every plan |
| MCP server | 43 tools on every plan: users, segments, templates, sends, exports; no journey tools | Full Journeys and Data Pipelines API: creates automations, segments, templates and sends; a CLI for coding agents |
| Built-in AI | OneSignal AI agent on every plan | AI Agent, in beta, builds automations from a prompt; scheduled routines by plan |
Pricing
A worked example for an app with 20,000 users, all active on mobile each month, and 40,000 emails a month. OneSignal Growth: $19 platform fee, $240 for mobile MAU and $30 for the 20,000 emails above the included 20,000, is $289 a month. Customer.io Essentials: $100 for 5,000 profiles plus $135 for 15,000 more is $235 a month, with push and in-app included. OneSignal comes out cheaper when stored profiles far outnumber users active in the app each month.
| Capability | OneSignal | Customer.io |
|---|---|---|
| Entry plan | Free: mobile push and in-app up to 1,000 MAU, 10,000 emails a month | No free plan: a 14-day trial, or 12 months free for startups that raised under $10M |
| First paid plan | Growth from $19 a month, month to month | Essentials from $100 a month, month to month; Premium from $1,000 a month, billed yearly |
| Mobile push | $0.012 per MAU on Growth | Unlimited on every plan |
| 20,000 sends a month on Growth, then $1.50 per 1,000 | 1 million sends a month on Essentials, then $0.12 per 1,000 |
FAQ
Is OneSignal better than Customer.io?
OneSignalOneSignal is better for a small team whose users live in the app or on the website, that wants push, web push and in-app messages live quickly on a free plan and month-to-month pricing.
Customer.ioCustomer.io is better for a lifecycle team that runs email-led journeys on event data, models accounts and orders alongside people, or messages users on WhatsApp or LINE, and can take on a steeper learning curve.
Which is cheaper, OneSignal or Customer.io?
They bill on different units. OneSignal charges a platform fee plus $0.012 per mobile monthly active user on Growth, with email and web push priced by send and subscriber. Customer.io charges by stored profile, $0.009 each above the 5,000 in Essentials, with push and in-app unlimited. Below 1,000 active app users OneSignal is free. Above that, Customer.io is cheaper when most stored profiles open the app every month, and OneSignal is cheaper when they do not.
Can I use OneSignal and Customer.io together?
Yes. Customer.io’s documentation shows a webhook step that sends web push through OneSignal, which covers the channel Customer.io lacks. Each tool keeps its own users and opt-outs, so an unsubscribe in one does not reach the other unless you sync them.
What moves when switching from OneSignal to Customer.io?
Users move as a CSV export from OneSignal without push tokens, and devices register again when the app with the Customer.io SDK identifies each user. Data tags become attributes, segments and journeys are rebuilt, and templates are copied over. Web push stays on OneSignal or another provider. Customer.io’s push migration guide covers the steps.
What if we need more than a campaign tool gives?
SuprSend, which publishes this page, runs product alerts and customer engagement messages from workflows that batch events into digests, fall back between providers and follow each user’s channel choices, with every step logged.