One API for every customer conversation
WhatsApp, Instagram and Facebook DMs, SMS and iMessage in one inbox you build yourself. Let an AI agent answer first, and step in when it matters.
- SOC 2
- GDPR compliant
- 99.97% uptime
Join 200,000+ of the world's most ambitious developers and builders
Why Zernio?
A stack of vendors, or one API
A telecom vendor, a WhatsApp provider and an inbox tool
Three vendors for one conversation
Separate contracts, bills and logins for each channel.
Customers split across tools
The same person is a stranger on every channel.
Inbox tools priced per seat
Adding a teammate raises the bill.
A closed inbox
You get their screens, not something to build on.
Customer messaging on Zernio
Every channel behind one API
WhatsApp, social DMs, SMS and iMessage in the same inbox.
Your own flow
Messages arrive as webhooks, and replies go out from your app.
An agent can answer
Connect your AI agent and hand over to a person when needed.
No markup on Meta's fees
WhatsApp templates are billed by Meta directly.
From first number to first reply in three steps
SMS, iMessage, WhatsApp
Connect a channel, or buy a number
Bring your own WhatsApp number and social accounts, or buy a number and turn on SMS and iMessage on it.
Every message arrives the same way
A DM, a WhatsApp message or a text reaches your app as one webhook, in one format, with the conversation it belongs to.
Reply from code, a person or an agent
One request sends the reply on whichever channel the customer used. Your team and your agent share the same thread.
Customer communication that fits your business, not a tool's idea of it
Priya N. · WhatsApp
Can I move my session to Friday?
Dana R. · Instagram DM
Do you take new clients?
Tom Becker · SMS
Running 10 minutes late
Leah Marx · Messenger
What are your prices?
One inbox inside your own app
Put every channel in the CRM or tool your team already works in, with the history in one thread per customer.
An AI agent that answers first
Your agent reads each message and replies in seconds, then hands the thread to a person when the question needs one.
Broadcasts and sequences
Send WhatsApp templates to a contact list, or a timed series of follow-ups.
Comment-to-DM
Answer a keyword comment on Instagram or Facebook with a private message.
iMessage
Reach customers in blue bubbles, with replies, voice notes and effects, and SMS as the fallback.
“That was a very big part that I wanted to have, and it wasn't possible before with the other WhatsApp service I used. But now I can build scheduling and communication flows with one Zernio API.”
6 hours a week saved on client feedbackA webhook in, a request out
Every channel uses the same two calls. Numbers, WhatsApp setup, delivery receipts and platform rules are handled on our side.
message.received
# what your app receives { "event": "message.received", "message": { "platform": "whatsapp", "text": "Can I move my session to Friday?" } } # how you answer, on any channel curl -X POST .../v1/inbox/conversations/{id}/messages \ -d '{ "accountId": "...", "message": "Friday at 16:30 is free." }'
Or put an agent on the line
Connect your AI agent to the inbox over MCP or webhooks.
your agent
message.received · whatsapp · Priya N. > "Can I move my session to Friday?" check calendar · 2 slots free call_tool · send message · whatsapp done · "Friday has 10:00 and 16:30 free." message.received · whatsapp · Priya N. > "16:30. My knee is still sore." handoff · thread passed to Leon
One inbox. One billing
Each channel you connect is one account. Phone numbers have a monthly fee, and calls and texts are billed by use.
Your first 2 accounts
$0
per month
Phone numbers with SMS
from $3 a month
Messages
first 10,000 a month free
WhatsApp templates
billed by Meta, no markup
Calls and SMS
from $0.010 a minute, $0.008 a text
Frequently Asked Questions
Answer every customer from one place
Connect a channel, receive the first message, send the first reply.
- SOC 2
- GDPR compliant
- 99.97% uptime