Sending images

Send images to Telegram, Discord, Slack, Mastodon, ntfy and Bluesky. Pass a url or raw bytes, and the upload, the size limits and spoilers are handled for you.

Some services fetch a url for you. Some refuse urls and want the file itself. One turns the file into the message. You write the same thing for all of them.

Copy this

server/api/screenshot.post.ts

export default defineEventHandler(async () => {
  await telegram.send('The failing step', {
    media: [{ url: 'https://example.com/shot.png', alt: 'The failing step' }],
  })

  return { ok: true }
})

That runs. Telegram hands the url on and fetches it itself. Mastodon and Bluesky cannot do that, so for them the module downloads it and uploads it for you. You do not choose, and you do not have to know which.

Two shapes, and only two

{ url: 'https://…/shot.png', alt: 'A screenshot', filename: 'shot.png' }
{ data: bytes,                alt: 'A screenshot', filename: 'shot.png', type: 'image/png' }

data takes a Blob, a Uint8Array or an ArrayBuffer. Everything else is optional.

No file paths, and no bare base64. A path would pull node:fs into the module, and that does not exist on Cloudflare Workers. Reading the file is two lines you write, and then it is bytes like everything else.

const data = await readFile('shot.png')
await telegram.send('Look', { media: [{ data }] })

Why both shapes exist everywhere

A url only version would force you to publish a private screenshot on the internet so that we can download it again. That is absurd, and in some places it is a data protection problem.

A bytes only version would drop Discord spoilers, which work exclusively on real attachments.

So both work everywhere, and each channel picks the cheaper route:

Channel	A url	Bytes
Telegram	handed over untouched, Telegram fetches it	multipart
ntfy	handed over as `attach`, ntfy fetches it	`PUT`, the body is the file
Discord	we fetch it, an attachment takes no url	multipart
Mastodon	we fetch it, `/api/v2/media` takes a file only	native
Bluesky	we fetch it, `uploadBlob` wants raw bytes	native
Slack	we fetch it, three step upload	native

Limits, and they are not close to each other

Channel	Per file	How many
Discord	10 MB	10
Bluesky	about 1 MB	4
Mastodon	instance decides, often 10 MB	4, instance decides
Telegram	Telegram's own, generous	one album

Bluesky's 1 MB is the one that will hit you. A normal screenshot is three to five times that. Official clients quietly resize before uploading, and this module does not: resizing is a decision about your content and would mean a dependency. You get the real number in the refusal instead, before anything is sent.

What will cost you an hour

Telegram's caption limit is 1024, not 4096. Adding an image lowers the limit of the text you already wrote.
A Discord spoiler only works on an attachment, through a SPOILER_ filename prefix. On an embed.image.url it is ignored, no error, just not hidden.
Mastodon answers 202 while it is still processing a large upload, and posting before it finishes is refused. The module waits for you.
Slack needs the bot in the channel to upload. chat:write.public covers messages but not files, so /invite it once.
A Slack upload has no message timestamp. The file becomes the message and Slack answers without a ts, so it can be deleted but never edited.

Changing and removing - including what happens to attachments on an edit
Bluesky - link cards, and why one post holds one embed
Discord - embeds and spoilers

Sending text

Send text to Telegram, Discord, Slack, ntfy, Mastodon and Bluesky with one verb. Formatting differs per service, and every limit is checked before sending.

Changing and removing

Edit and delete messages you already sent on Telegram, Discord, Slack, ntfy and Mastodon. The result of send is the handle, and the types say who cannot.