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Slack messaging API · live on Free

Post to Slack the same way you send an email.

Connect your Slack workspace once with a single click, then post to channels, direct messages or threads using the same /v1/send endpoint that sends your email. Rich Block Kit formatting is supported, and inbound Slack events stream straight into your Logs.

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● Free forever · No card · All 6 channels · AI credits
POST /v1/send · channel: slack
200 OK · 38ms
curl https://api.senddio.com/v1/send \
  -H "Authorization: Bearer sdo_live_…" \
  -H "Content-Type: application/json" \
  -d '{
    "channel": "slack",
    "to":      "#ops-alerts",
    "blocks": [
      { "type": "header", "text": "Anomaly detected" },
      { "type": "section",
        "text": "Bounce rate ↑ 3.4× on @acme.dev",
        "fields": [{"type":"mrkdwn","text":"Window: last 6h"}] }
    ]
  }'
Channel
Slack
Slack OAuth + Web API
Free plan
100/mo
sampler limit
Same endpoint
/v1/send
POST · Bearer auth
Latency
<50ms
queue accept · p99
How it works

Slack, like another channel.

Same endpoint as your email and SMS. No tokens to rotate. No webhooks to babysit. Just messages where your team already lives.

01
Step 01
You click “install”.
OAuth runs. The Senddio bot joins your workspace with the smallest set of permissions that does the job.
02
Step 02
You write a message.
Channel, DM, or thread. Block Kit pass-through if you want it. Plain string if you don't.
03
Step 03
It posts instantly.
Like a teammate did it. Signed by your app. Audited end-to-end. The legacy webhooks you used to maintain quietly stop mattering.
04
Step 04
Replies flow back to you.
Threads stay threaded. Conversations stay continuous. Your agent or bot can keep the thread going without you.

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

The shift

Replace eight one-off Slack webhooks with one line.

  • No more rotating Slack tokens at midnight.
  • No more reinstalling apps when permissions drift.
  • 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 the chart attachedAgent 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 the chart attachedAgent 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 auto-threaded under the incidentHiring 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 auto-threaded under the incidentHiring 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 to channels, DMs, threads, or by user ID
  • Block Kit blocks + attachments supported
  • Inbound Slack events streamed into Logs
  • Reply-in-thread for back-and-forth flows
  • Per-workspace channel allow-list
  • Agent-tagged sends visible in dashboard
From teams who switched

You're in good company on Slack.

Composite quotes from interviews with current Senddio customers shipping slack in production.

We removed three internal Slack notifier services in one afternoon. Nobody noticed except the operations team, and they sent thank-you messages all week.
Kai L.
Site reliability engineer · series-C SaaS
Senddio passes Slack Block Kit through unchanged. Our existing message builders kept working. The migration was one find-and-replace and a coffee.
Riya V.
Platform engineer · adtech
Anomaly detection finally has the right place to land. Our operations channel is busy in the best possible way.
Théo B.
Engineering manager · infrastructure team
Compared to your alternatives

Senddio Slack vs. building with the Slack SDK

FeatureSenddioDoing it yourself
OAuth flow + token refreshHostedYours
Webhook signature verificationVerified for youYours
Unified Logs + retry queueSame as emailBuild it
Channel fallbackSlack → email cascadeYou wire it
Block Kit supportPass-throughNative
Your next 30 days

What changes once you ship Slack on Senddio.

01
Day 1
OAuth installed, first message in #engineering
02
Day 3
Block Kit alerts replacing your legacy webhook pile
03
Week 1
Inbound events threading under outbound sends
04
Day 30
One integration, zero token rotations — forever
●Every milestone above ships on the Free plan. No card, no upgrade gate.
FAQ

Slack — FAQ

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.

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.

Yes. Block Kit messages pass through unchanged to Slack. Senddio does not wrap or re-flow your blocks, so anything that works in Slack works in Senddio.

Slack's Events API delivers events to a Senddio webhook. Senddio verifies the signing secret, threads the event under the related outbound message when possible, and surfaces it in your Logs feed for routing.

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
Email
Transactional email API
SMS
Programmable SMS API
WhatsApp
WhatsApp Business API
Push
Push notification API
Telegram
Telegram bot messaging

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