Alerts with attachments
Everything below rests on one rule: a channel asks, and the phone decides. What arrives is guaranteed; how loudly it arrives is not, and any page that told you otherwise was selling.
A picture, a sound or a document, when words are not enough
A diverted bus route is a map. A boil-water notice is a paragraph of instructions people will re-read. An alert can carry an image, a sound file or a document alongside the text. Documents are stored exactly as written and re-rendered from a sanitised copy rather than being run as markup, so an attachment cannot turn into a script on somebody’s lock screen. The bytes are uploaded once and attached by reference, which keeps a send cheap however large the audience.
Draft, schedule, send — and what cancelling cannot undo
Composing and sending are deliberately different permissions, so the person or script that writes an alert can be forbidden from publishing it. A scheduled alert becomes visible at its time without anything having to run at that minute, which means a server that was briefly down delivers late rather than never. Cancelling is honest about its limits: it stops an alert reaching phones that have not fetched it yet and does nothing at all to the phones that already have it. An alert cannot be unsent.
Questions, answered plainly
Can I attach a map or a PDF?
You can attach an image, a sound file or a document. A document is stored exactly as submitted and rendered from a sanitised copy, so it can never execute anything on a subscriber’s phone.
Can I unsend an alert?
No. Cancelling stops it reaching phones that have not fetched it yet, and does nothing to the ones that already have it. Compose as a draft and read it back before you send; that habit is worth more than any undo button we could offer.
Do subscribers need an account?
No. They install the app, subscribe to a handle, and that is the whole of it. Only the person running the channel signs up for anything.
How do people find my channel?
From the handle you give them: on a poster, in an enrolment email, on a QR code, in a footer. Public channels also appear in the app’s discover list. Sealed ones appear nowhere at all, by design.
Say it once. Every subscribed phone gets it.
Free up to 100 subscribers, no card to start, and the handle is yours permanently.
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