Upload media

To send an image, a PDF or any other file, upload it first. You get back a med_ id, and that id is what you send — not the bytes. Upload once, send it to a thousand people.

Upload

const media = await msg.media.upload(file, "invoice.pdf");
// media.id -> "med_7c1d2e3f..."

The file is stored and registered with WhatsApp in the same call, so the id works immediately — there is nothing to wait for and no second step.

What comes back

Field	What it is
`id`	The `med_` id. This is what you send with.
`filename`	The name you uploaded it under.
`mimeType`	The type we normalised to, which may differ from the one you declared.
`sizeBytes`	Size of the stored file.

Size limits

WhatsApp caps each kind of file, and we check before storing anything, so an oversized file is refused at upload rather than at send.

Kind	Cap
Image	5 MB
Video, audio	16 MB
Document	100 MB
Sticker	500 KB

Keep the id. Uploading the same file again gives you a second copy and a second id.

A test key uploads for real — see Test keys and the sandbox.

Then send it

Pass the id as mediaId — see Send a message.