What is the difference between Sendblue and Zernio?

Sendblue supports 58 of the 77 features compared here, and Zernio supports 57. Sendblue adds iMessage apps, live app cards, FaceTime calls, iMessage availability check and line pooling. Zernio adds edit and unsend, stickers, formatted text, WhatsApp and Telegram.

How much do Sendblue and Zernio cost?

Sendblue: A free sandbox for testing, the AI Agent plan at $100 per line per month for inbound-first use, and custom Enterprise pricing for outbound and volume. Zernio: An iMessage sender costs $200 a month plus Zernio's per-account fee, with a free sandbox; SMS, calls and outbound messages past 10,000 a month are metered.

Does Zernio support iMessage apps?

Zernio does not list iMessage apps on its site or in its docs.

Does Zernio support live app cards?

Zernio does not list live app cards on its site or in its docs.

Does Zernio support FaceTime calls?

Zernio does not list FaceTime calls on its site or in its docs.

Sendblue vs Zernio: Features, Pricing and Differences

Feature comparison

Feature	Sendblue	Zernio
iMessage messaging
iMessage	Supported	Supported
Group chats	BetaGroup API is in beta on select plans. AI Agent plan can only reply in existing groups.	SupportedGroups on ordered senders: reply, create, rename, photo, members. Not on the sandbox line.
Group management	BetaAdd and remove participants in iMessage groups via the beta groups API.	SupportedStart a group from a sender and add or remove participants; applied asynchronously.
Group name and photo	SupportedRename groups and set group photos on supported lines.	SupportedRename a group or change its photo, one change per call.
Mentions	Not listed	Not listed
Tapbacks	PartialSend classic tapbacks or any emoji. No inbound reaction events documented.	SupportedSix Apple tapbacks plus custom emoji (iOS 18+). Inbound reactions arrive by webhook.
Threaded replies	Supportedreply_to on V2 iMessage lines, in direct and group chats.	SupportedreplyTo on sends; inbound messages carry the reply thread id.
Typing indicators	SupportedSend and receive. iMessage 1:1 only, not in groups.	PartialSend only, 1:1 chats, about 15 seconds, after a recent two-way exchange.
Read receipts	PartialCan mark chats read (1:1). Outbound statuses stop at DELIVERED, with no read status.	PartialMark a chat read inside an active two-way chat. Webhook docs list message.read for other platforms only.
Edit and unsend	Not supportedDocs say editing is not supported via API and delete does not unsend.	SupportedEdit text within 15 minutes; unsend within 2 minutes removes the bubble for the recipient.
Message effects	Supported13 send_style values.	Supported13 screen and bubble effects, such as slam, invisibleInk, confetti and fireworks.
Animated text effects	Not listed	Not listed
Stickers	Not listed	PartialInbound stickers are typed as sticker. Sending stickers is not documented.
Formatted text	Not listed	SupportedInline bold, _italic_, __underline__ and ~strikethrough~ markup renders as rich text.
Attachments	SupportedUp to 100MB on iMessage, 5MB on SMS.	SupportedUp to 10 per message, each a public https URL of at most 256 characters.
Live Photos	Not listed	Not listed
Rich link previews	PartialDocs say links expand only after the recipient saves your contact.	SupportedOn by default; linkPreview: false sends links as plain text.
Voice messages	SupportedSend .caf files to render as inline voice notes.	SupportedvoiceNote: true on an audio file. Inbound voice messages come with a transcript.
Contact cards	SupportedSend .vcf files via media_url.	PartialcontactCard shares the sender's own card only.
Polls	Not listed	Not listed
Chat backgrounds	Not listed	Not listed
Location sharing	SupportedFind My request, read and live watch. Dedicated iMessage lines only.	PartialStatic location pins only. Inbound shared locations arrive without coordinates.
iMessage apps	SupportedApp Cards for your own Messages extension. V2 lines, not on the free plan.	Not listed
Live app cards	PartialUpdates go out as new messages in the same App Card session; Sendblue says the original is not edited.	Not listed
Sender name and photo	SupportedName and Photo Sharing profile per line, shared into direct iMessage chats.	PartialSets the name and photo on the sender's contact card, which recipients see when they save it.
FaceTime calls	PartialOutbound FaceTime audio over WebRTC (Agora). Needs a purchased FaceTime line.	Not listedInbound FaceTime attempts show in the thread as call-typed messages. No calling documented.
Delivery status	SupportedStatus callbacks from REGISTERED through SENT or DELIVERED.	Supportedmessage.delivered and message.failed webhooks; sends deferred for pacing show as queued.
iMessage availability check	SupportedLookup API checks a phone number or email for iMessage.	Not listed
Focus and Notify Anyway	Not listed	Not listed
Numbers and delivery
Managed lines	Supported	SupportedZernio orders numbers on its delivery provider's Apple-registered infrastructure.
Dedicated numbers	Supported	SupportedUS or UK numbers, some active instantly; email-handle senders through the API.
Shared numbers	SupportedFree sandbox uses a shared number with verified contacts only.	SupportedFree shared sandbox line for testing: contact writes first, 5 contacts, 50 messages a day.
Bring your own number	PartialOnly by porting the number in, which adds 3 to 5 days.	PartialiMessage cannot run on a number you own. A sender held with the provider can be registered.
Line pooling	SupportedNumber pooling with sticky sending. Automatic line selection needs account enablement.	Not listedOne sender per profile; docs suggest spreading contacts across senders by hand.
SMS fallback	Supported	SupportedSMS or RCS from the same number when the contact is not on iMessage.
RCS fallback	SupportediMessage, then RCS, then SMS. RCS on V2 lines.	SupportedSMS or RCS from the same number; the provider picks per contact.
Outbound-first messaging	SupportedFull outbound on Enterprise or Blue Ocean; Free and AI Agent plans are inbound-first	SupportedOne new chat per 15 minutes per sender, warm-up from 2 to 50 a day, no links in openers.
Calls on the iMessage number	SupportedDashboard calls and FaceTime from the texting number; API calls via your Twilio caller ID.	PartialOrdered numbers include call forwarding. Placing calls from the iMessage number is not documented.
Other channels
SMS	Supported	Supported
RCS	SupportedV2 lines.	Supported
WhatsApp	Not supportedNot offered	Supported
Telegram	Not supported	Supported
Slack	Not listed	Supported
Email	Not supportedNot offered. iMessage can be sent to Apple ID email addresses.	Not supportedNot offered as a channel. iMessage senders can use an email handle.
Phone calls	PartialNo native calling API. Dashboard calls, outbound via your Twilio caller ID, inbound forwarding.	SupportedInbound and outbound PSTN calls, SIP trunks, browser softphone, recording and transcription.
Apple Messages for Business	Not supportedNot offered	Not supportedNot offered
Unified channel API	SupportedOne API for iMessage, RCS and SMS, the only channels offered.	SupportedSame inbox send call and webhooks for iMessage, SMS, WhatsApp, Telegram, Slack and social DMs.
Developer tools
REST API	Supported	Supported
TypeScript SDK	Supportedsendblue on npm.	Supported@zernio/node
Python SDK	Supportedsendblue on PyPI.	Supportedzernio-sdk
Other SDKs	PartialGo, Rust and Ruby packages, listed as community packages.	SupportedGo, Ruby, Java, PHP, .NET and Rust.
CLI	Supported@sendblue/cli: signup, messaging, contacts and webhooks.	SupportedZernio CLI, including iMessage inbox sends and reactions.
Webhooks	Supported	Supported
Signed webhooks	PartialSends your shared secret in an sb-signing-secret header. No HMAC signature.	SupportedHMAC-SHA256 of the raw body in X-Zernio-Signature, keyed by your secret.
MCP server	Supportedsendblue-api-mcp via npx.	SupportedHosted at mcp.zernio.com/mcp, with OAuth sign-in or an API key.
Open source	PartialSDKs and CLI are MIT or Apache-2.0 on GitHub. The messaging platform is closed.	PartialSDKs, CLI, n8n node and Chat SDK adapter are MIT or Apache-2.0. The platform is closed.
Self-hosting	Not listedSold as a hosted service on Sendblue's Apple devices; self-hosting is not mentioned.	Not supportedHosted cloud service only
Local testing	Not listed	Not listedThe free sandbox still needs your own phone or Apple ID.
Custom channel providers	Not listed	Not listed
Event replay	PartialNo replay. Docs say to repair gaps by listing messages updated since a timestamp.	Supported7 attempts over about 51 hours, then dead-letter; any past event can be redelivered.
OpenTelemetry	Not listed	Not listed
No-code integrations	SupportedZapier, Make and GoHighLevel. Docs FAQ says n8n resources are coming soon.	Partialn8n, Make and Zapier guides cover posting; Make's API call module reaches any endpoint.
CRM integrations	SupportedGoHighLevel, HubSpot, Salesforce, Close and Monday.com.	SupportedHubSpot: inbox contacts and messages sync to HubSpot timelines.
Built for AI agents
Agent framework	PartialNo own framework. Maintains a Vercel Chat SDK adapter.	PartialWorkflow engine with AI and handoff nodes; the workflow docs do not list iMessage.
Agent framework integrations	SupportedSendblue-maintained Vercel Chat SDK adapter.	PartialVercel Chat SDK adapter (iMessage not listed) and an OpenClaw skill.
Streaming replies	Not supportedDocs say message editing is not supported via the API.	PartialChat SDK adapter streams by editing on Telegram only.
Agent group chats	BetaA line can add another of your own dedicated lines to a group, via the beta groups API.	Not listed
Human handoff	SupportedShared team inboxes with assignment, and agents that escalate to a rep.	PartialDashboard inbox and workflow handoff nodes; no iMessage-specific handoff documented.
Audit logs	PartialSecurity page says all API requests are logged. No customer-facing audit log documented.	SupportedAppend-only log of team-management actions; Enterprise adds broader audit logs.
Message history API	Supported	Supported
Plans and compliance
Free plan	SupportedFree sandbox: shared number, up to 10 verified contacts, no webhooks.	SupportedFirst 2 connected accounts free; free iMessage sandbox (5 contacts, 50 messages a day).
Public pricing	SupportedAI Agent plan at $100/mo per line. Enterprise is custom.	Supported$200 per iMessage sender per month, plus the connected-account fee.
No per-message fees	Supported	PartialiMessage pages say no per-message fee; an outbound meter of $1 per 10,000 after 10,000 starts Oct 2026.
Uptime SLA	Supported99.99% uptime SLA on the Enterprise plan	Not listedSite states 99.97% uptime; no contractual SLA found.
Isolated infrastructure	SupportedA dedicated HIPAA instance for HIPAA customers	Not listed
SOC 2 Type II	SupportedSOC 2 Type II, report on request.	SupportedSOC 2 Type II report in the trust portal, by access request.
GDPR	SupportedPrivacy policy says Sendblue adheres to GDPR. DPAs on request.	SupportedGDPR documentation in the trust portal; public DPA.

Feature

Sendblue

Zernio

iMessage messaging

iMessage

Group chats

BetaGroup API is in beta on select plans. AI Agent plan can only reply in existing groups.

Groups on ordered senders: reply, create, rename, photo, members. Not on the sandbox line.

Group management

BetaAdd and remove participants in iMessage groups via the beta groups API.

Start a group from a sender and add or remove participants; applied asynchronously.

Group name and photo

Rename groups and set group photos on supported lines.

Rename a group or change its photo, one change per call.

Mentions

Not listed

Tapbacks

PartialSend classic tapbacks or any emoji. No inbound reaction events documented.

Six Apple tapbacks plus custom emoji (iOS 18+). Inbound reactions arrive by webhook.

Threaded replies

reply_to on V2 iMessage lines, in direct and group chats.

replyTo on sends; inbound messages carry the reply thread id.

Typing indicators

Send and receive. iMessage 1:1 only, not in groups.

PartialSend only, 1:1 chats, about 15 seconds, after a recent two-way exchange.

Read receipts

PartialCan mark chats read (1:1). Outbound statuses stop at DELIVERED, with no read status.

PartialMark a chat read inside an active two-way chat. Webhook docs list message.read for other platforms only.

Edit and unsend

Not supportedDocs say editing is not supported via API and delete does not unsend.

Edit text within 15 minutes; unsend within 2 minutes removes the bubble for the recipient.

Message effects

13 send_style values.

13 screen and bubble effects, such as slam, invisibleInk, confetti and fireworks.

Animated text effects

Not listed

Stickers

Not listed

PartialInbound stickers are typed as sticker. Sending stickers is not documented.

Formatted text

Not listed

Inline *bold*, _italic_, __underline__ and ~strikethrough~ markup renders as rich text.

Attachments

Up to 100MB on iMessage, 5MB on SMS.

Up to 10 per message, each a public https URL of at most 256 characters.

Live Photos

Not listed

Rich link previews

PartialDocs say links expand only after the recipient saves your contact.

On by default; linkPreview: false sends links as plain text.

Voice messages

Send .caf files to render as inline voice notes.

voiceNote: true on an audio file. Inbound voice messages come with a transcript.

Contact cards

Send .vcf files via media_url.

PartialcontactCard shares the sender's own card only.

Polls

Not listed

Chat backgrounds

Not listed

Location sharing

Find My request, read and live watch. Dedicated iMessage lines only.

PartialStatic location pins only. Inbound shared locations arrive without coordinates.

iMessage apps

App Cards for your own Messages extension. V2 lines, not on the free plan.

Not listed

Live app cards

PartialUpdates go out as new messages in the same App Card session; Sendblue says the original is not edited.

Not listed

Sender name and photo

Name and Photo Sharing profile per line, shared into direct iMessage chats.

PartialSets the name and photo on the sender's contact card, which recipients see when they save it.

FaceTime calls

PartialOutbound FaceTime audio over WebRTC (Agora). Needs a purchased FaceTime line.

Not listedInbound FaceTime attempts show in the thread as call-typed messages. No calling documented.

Delivery status

Status callbacks from REGISTERED through SENT or DELIVERED.

message.delivered and message.failed webhooks; sends deferred for pacing show as queued.

iMessage availability check

Lookup API checks a phone number or email for iMessage.

Not listed

Focus and Notify Anyway

Not listed

Numbers and delivery

Managed lines

Zernio orders numbers on its delivery provider's Apple-registered infrastructure.

Dedicated numbers

US or UK numbers, some active instantly; email-handle senders through the API.

Shared numbers

Free sandbox uses a shared number with verified contacts only.

Free shared sandbox line for testing: contact writes first, 5 contacts, 50 messages a day.

Bring your own number

PartialOnly by porting the number in, which adds 3 to 5 days.

PartialiMessage cannot run on a number you own. A sender held with the provider can be registered.

Line pooling

Number pooling with sticky sending. Automatic line selection needs account enablement.

Not listedOne sender per profile; docs suggest spreading contacts across senders by hand.

SMS fallback

SMS or RCS from the same number when the contact is not on iMessage.

RCS fallback

iMessage, then RCS, then SMS. RCS on V2 lines.

SMS or RCS from the same number; the provider picks per contact.

Outbound-first messaging

Full outbound on Enterprise or Blue Ocean; Free and AI Agent plans are inbound-first

One new chat per 15 minutes per sender, warm-up from 2 to 50 a day, no links in openers.

Calls on the iMessage number

Dashboard calls and FaceTime from the texting number; API calls via your Twilio caller ID.

PartialOrdered numbers include call forwarding. Placing calls from the iMessage number is not documented.

Other channels

SMS

RCS

V2 lines.

Not supportedNot offered

Not supported

Slack

Not listed

Not supportedNot offered. iMessage can be sent to Apple ID email addresses.

Not supportedNot offered as a channel. iMessage senders can use an email handle.

Phone calls

PartialNo native calling API. Dashboard calls, outbound via your Twilio caller ID, inbound forwarding.

Inbound and outbound PSTN calls, SIP trunks, browser softphone, recording and transcription.

Apple Messages for Business

Not supportedNot offered

Unified channel API

One API for iMessage, RCS and SMS, the only channels offered.

Same inbox send call and webhooks for iMessage, SMS, WhatsApp, Telegram, Slack and social DMs.

Developer tools

REST API

TypeScript SDK

sendblue on npm.

@zernio/node

Python SDK

sendblue on PyPI.

zernio-sdk

Other SDKs

PartialGo, Rust and Ruby packages, listed as community packages.

Go, Ruby, Java, PHP, .NET and Rust.

CLI

@sendblue/cli: signup, messaging, contacts and webhooks.

Zernio CLI, including iMessage inbox sends and reactions.

Webhooks

Signed webhooks

PartialSends your shared secret in an sb-signing-secret header. No HMAC signature.

HMAC-SHA256 of the raw body in X-Zernio-Signature, keyed by your secret.

MCP server

sendblue-api-mcp via npx.

Hosted at mcp.zernio.com/mcp, with OAuth sign-in or an API key.

Open source

PartialSDKs and CLI are MIT or Apache-2.0 on GitHub. The messaging platform is closed.

PartialSDKs, CLI, n8n node and Chat SDK adapter are MIT or Apache-2.0. The platform is closed.

Self-hosting

Not listedSold as a hosted service on Sendblue's Apple devices; self-hosting is not mentioned.

Not supportedHosted cloud service only

Local testing

Not listed

Not listedThe free sandbox still needs your own phone or Apple ID.

Custom channel providers

Not listed

Event replay

PartialNo replay. Docs say to repair gaps by listing messages updated since a timestamp.

7 attempts over about 51 hours, then dead-letter; any past event can be redelivered.

OpenTelemetry

Not listed

No-code integrations

Zapier, Make and GoHighLevel. Docs FAQ says n8n resources are coming soon.

Partialn8n, Make and Zapier guides cover posting; Make's API call module reaches any endpoint.

CRM integrations

GoHighLevel, HubSpot, Salesforce, Close and Monday.com.

HubSpot: inbox contacts and messages sync to HubSpot timelines.

Built for AI agents

Agent framework

PartialNo own framework. Maintains a Vercel Chat SDK adapter.

PartialWorkflow engine with AI and handoff nodes; the workflow docs do not list iMessage.

Agent framework integrations

Sendblue-maintained Vercel Chat SDK adapter.

PartialVercel Chat SDK adapter (iMessage not listed) and an OpenClaw skill.

Streaming replies

Not supportedDocs say message editing is not supported via the API.

PartialChat SDK adapter streams by editing on Telegram only.

Agent group chats

BetaA line can add another of your own dedicated lines to a group, via the beta groups API.

Not listed

Human handoff

Shared team inboxes with assignment, and agents that escalate to a rep.

PartialDashboard inbox and workflow handoff nodes; no iMessage-specific handoff documented.

Audit logs

PartialSecurity page says all API requests are logged. No customer-facing audit log documented.

Append-only log of team-management actions; Enterprise adds broader audit logs.

Message history API

Plans and compliance

Free plan

Free sandbox: shared number, up to 10 verified contacts, no webhooks.

First 2 connected accounts free; free iMessage sandbox (5 contacts, 50 messages a day).

Public pricing

AI Agent plan at $100/mo per line. Enterprise is custom.

$200 per iMessage sender per month, plus the connected-account fee.

No per-message fees

PartialiMessage pages say no per-message fee; an outbound meter of $1 per 10,000 after 10,000 starts Oct 2026.

Uptime SLA

99.99% uptime SLA on the Enterprise plan

Not listedSite states 99.97% uptime; no contractual SLA found.

Isolated infrastructure

A dedicated HIPAA instance for HIPAA customers

Not listed

SOC 2 Type II

SOC 2 Type II, report on request.

SOC 2 Type II report in the trust portal, by access request.

GDPR

GDPR documentation in the trust portal; public DPA.

Checked on each provider's own site and docs on 2026-10-25. “Not listed” means the provider does not mention it.

Sendblue vs Zernio

Compare Sendblue and Zernio side by side: iMessage features, channels, developer tools, pricing and compliance, checked on each provider's own site.

Sendblue

Zernio

Where Sendblue is ahead

Where Zernio is ahead

Feature comparison

Pricing

Sendblue

Zernio

Which should you choose?

Frequently asked questions

More Sendblue comparisons

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