Slack messaging API · live on Free

Post to Slack the same way you send an email.

Connect your Slack workspace with OAuth, then post text to channel or user IDs through the same /v1/send endpoint used by every Senddio channel. Verified inbound Slack events stream into Logs.

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POST /v1/send · channel: slack

202 Accepted

curl https://api.senddio.com/v1/send \
  -H "Authorization: Bearer sdo_live_…" \
  -H "Content-Type: application/json" \
  -d '{
    "channel": "slack",
    "to":      "C0123456789",
    "body":    "Anomaly detected: bounce rate ↑ 3.4× on acme.dev"
  }'

Channel

Slack

Slack OAuth + Web API

Free plan

100/mo

sampler limit

Same endpoint

/v1/send

POST · Bearer auth

Acceptance

202

queued, not delivered

How it works

Slack, like another channel.

Connect Slack once, then use the same endpoint and Logs as your email and SMS. Keep your installation permissions current.

Step 01

You click “install”.

OAuth runs. The Senddio bot joins your workspace with the smallest set of permissions that does the job.

Step 02

You write a message.

Use a Slack channel ID or user ID and supply a plain text body. Block Kit mode can be enabled on the channel connection.

Step 03

It queues your message.

Like a teammate did it. Signed by your app. Audited end-to-end. The legacy webhooks you used to maintain quietly stop mattering.

Step 04

Replies flow back to you.

Verified inbound events appear in Logs and can be forwarded to your application through MESSAGE_RECEIVED webhooks.

One endpoint, one key, one bill. That is all.

The shift

Replace eight one-off Slack webhooks with one line.

Keep Slack credentials in a configured channel connection.
Review installation permissions when your integration changes.
No more wondering which old script just woke up the team.
No more “let me check the old integration” in every incident.

The room gets quieter. The signal gets sharper.

Beyond the obvious

Whatever your team can imagine, this endpoint will send.

Real teams ship slack on Senddio for everything from order receipts to late-night customer apologies. Here are a few of the things they have built — and the kinds of things your team will dream up next month.

Anomaly alert with a chart linkAgent shift report at end of dayCustomer signup ping with the plan sizeOn-call escalation when SMS got ignoredDeploy notification with the diff linkPR merged to main, by who, how bigPayment received over $10k, with confettiRefund issued, with the reason in the threadCustomer churned, with the last-touch sessionSentiment digest from yesterday’s supportAI weekly summary every Monday 8amAnomaly alert with a chart linkAgent shift report at end of dayCustomer signup ping with the plan sizeOn-call escalation when SMS got ignoredDeploy notification with the diff linkPR merged to main, by who, how bigPayment received over $10k, with confettiRefund issued, with the reason in the threadCustomer churned, with the last-touch sessionSentiment digest from yesterday’s supportAI weekly summary every Monday 8am

Support escalation with the agent’s notesSecurity audit alert with the IP and countrySystem status update on every state changeCalendar reminder for the standupOKR check-in nudge at end of quarterRetro digest with the action itemsAI standup compiler from yesterday’s PRsPostmortem notes with an incident linkHiring pipeline update by stageBirthday reminder to your manager onlyNew-hire welcome with the right channels listedSupport escalation with the agent’s notesSecurity audit alert with the IP and countrySystem status update on every state changeCalendar reminder for the standupOKR check-in nudge at end of quarterRetro digest with the action itemsAI standup compiler from yesterday’s PRsPostmortem notes with an incident linkHiring pipeline update by stageBirthday reminder to your manager onlyNew-hire welcome with the right channels listed

The thing you'll build next month

If you can describe it in one sentence, you can ship it on /v1/send.

Read the docs

What you get

Production-ready slack, on day one.

The boring infrastructure — signing, retries, suppressions, webhook verification, audit — is done. Your code is one POST.

Slack OAuth installation flow
Send text to channel IDs or user IDs
Optional Block Kit mode configured per connection
Inbound Slack events streamed into Logs
Provider failures classified for safe retries
Per-recipient suppression handling
Agent-tagged sends visible in dashboard

Compared to your alternatives

Senddio Slack vs. building with the Slack SDK

FeatureSenddioDoing it yourself

OAuth installationHostedYours

Webhook signature verificationVerified for youYours

Unified Logs + retry queueSame as emailBuild it

Channel fallbackUse /v1/notifyYou wire it

Block Kit modeJSON body when enabledNative

Your next 30 days

What changes once you ship Slack on Senddio.

Day 1

OAuth installed, first message in #engineering

Day 3

Block Kit alerts replacing your legacy webhook pile

Monitor

Verified inbound events visible in Logs

Maintain

Review permissions and provider errors

FAQ

Slack — FAQ

How do I connect Senddio to my Slack workspace?

Go to Channels, then Slack, then Install in your Senddio dashboard. You are redirected to Slack's standard authorisation screen, which asks for the minimum permissions Senddio needs to read channel names and post messages. Tokens are encrypted at rest and only shown as masked secrets.

Can Senddio post to private Slack channels?

Yes, after the Senddio bot is invited to the private channel — that is a Slack rule, not a Senddio limitation. Public channels work the moment your workspace is connected.

Does Senddio support Slack Block Kit messages?

A Slack connection can enable Block Kit mode. In that mode, body must contain a JSON-encoded blocks array; the public request still uses the body field rather than a top-level blocks field.

How does Senddio handle inbound Slack events?

Slack's Events API delivers events to a Senddio webhook. Senddio verifies the signing secret and stores supported inbound messages in Logs for your application to consume.

Can my Claude or ChatGPT agent post Slack messages?

Yes, and it is one of the most popular patterns Senddio sees. Give the agent its own key, restrict it to Slack, and it can post the same way a human would. Every send is labelled with the agent name so you can audit AI traffic separately.

Other channels

Ship slack in 5 minutes.

Free forever — on the same plan as all 5 other channels, plus AI credits.

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● 300 emails/day · All 6 channels · AI credits · No card