What it is
Sooner or later your list needs to talk to something else: a CRM, a Discord bot, a spreadsheet, the app you're building on the side.
Kōlea sends a signed message to any URL you give it when someone subscribes, unsubscribes, bounces, or buys, and when you publish a post. If your end is down, it tries again later and keeps a log.
01 Webhooks
Five events, signed
Pick the events you care about and paste a URL. You get a signing secret once, with a snippet showing how to check it.
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An HMAC-SHA256 signature on every request, with a timestamp and a five-minute window, so you know it came from Kōlea and nobody replayed it.
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The same bytes on every retry, because the payload is frozen when the event happens. Your handler can safely dedupe on the event id.
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Rotate the secret whenever you like, the old one stops working straight away.
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Bulk imports don't fire anything, so moving 20,000 people over from Kit doesn't flood your CRM with 20,000 "subscribed" events.
Down for a bit? No problem
If your server doesn't answer, Kōlea waits and tries again: after 30 seconds, then 2 minutes, then 8, and so on up to 8 attempts over about 15 hours.
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A delivery log per endpoint, every attempt with its status code, the error, and how long it took, so you can see exactly what went wrong.
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It switches itself off after 15 failures in a row, and tells you why, instead of hammering a dead URL forever.
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Public https URLs only, checked every time, so nobody can point a webhook at your private network.
The short version
- Signed messages when someone subscribes, unsubscribes, bounces, or buys, and when you publish.
- If your app is down, Kōlea tries again later, and there's a log so you can see what happened.
Try it on your own list
Free for your first 500 subscribers, no credit card needed. We'll help you move your list over.