instax-web

Print to a Fujifilm INSTAX Link printer from the browser, over Web Bluetooth. No runtime dependencies, no server.

Supports mini, square, and wide film.

npm install instax-web

Credits

Extracted and rewritten from linssenste/instax-link-web (MIT). The protocol itself was reverse-engineered by Jasper van Loenen in javl/InstaxBLE.

Not affiliated with or endorsed by Fujifilm. INSTAX is a trademark of Fujifilm.

Usage

import { InstaxPrinter, prepareImage } from 'instax-web'

// Must run inside a user gesture — browsers block the device chooser otherwise.
button.addEventListener('click', async () => {
  const printer = await InstaxPrinter.request()
  const status = await printer.getStatus()

  const jpeg = await prepareImage(file, { variant: status.film ?? 'mini' })
  await printer.print(jpeg)

  await printer.disconnect()
})

prepareImage is the part that makes this work: the printer only accepts a JPEG at the film's exact pixel dimensions and under 60 KB, so quality is bisected until the output fits.

Progress and abort

const controller = new AbortController()

printer.on('progress', ({ phase, ratio }) => {
  bar.value = ratio // phase is 'uploading' or 'printing'
})

await printer.print(jpeg, { copies: 2, signal: controller.signal })

Aborting mid-upload sends the printer a cancel and rejects with code: 'aborted'.

Errors

Every failure is an InstaxError with a code you can branch on, so a dismissed chooser doesn't look like a hardware fault:

import { isInstaxError } from 'instax-web'

try {
  await InstaxPrinter.request()
} catch (error) {
  if (isInstaxError(error, 'cancelled')) return // user closed the picker
  if (isInstaxError(error, 'unsupported')) showBrowserWarning()
  throw error
}

Codes: unsupported, cancelled, disconnected, not-connected, timeout, invalid-packet, printer-error, image-too-large, aborted, not-ready.

API

| | | |---|---| | InstaxPrinter.isSupported() | Web Bluetooth available in this context | | InstaxPrinter.request(options?) | Show the chooser, connect, resolve a printer | | printer.getStatus() | Film size, battery, shots remaining | | printer.getIdentity() | Manufacturer, model id, serial | | printer.print(image, options?) | Upload and print. { copies, variant, signal, onProgress } | | printer.upload(image, options?) / printer.printLoaded(copies?) | Same, split in two | | printer.setLed(colors, options?) | Ring LED colour or animation | | printer.ejectFilmCover() | Eject a fresh pack's cover sheet. Ejects a real sheet — see below | | printer.shutdown() / printer.disconnect() | | | printer.on(event, listener) | connect, disconnect, progress, status. Returns an unsubscribe | | prepareImage(input, options) | { variant, fit, crop, rotate, background, maxBytes } → JPEG bytes |

print accepts a Blob, Uint8Array, ArrayBuffer, data URL, or base64 string. prepareImage accepts a Blob/File, ImageBitmap, HTMLImageElement, HTMLCanvasElement, or URL.

The protocol layer is exported too — encodePacket, decodePacket, Opcode, BleTransport — if you want to drive the printer directly. Pass your own transport to run without hardware; test/fake-printer.ts is a working example.

Browser support

Needs Web Bluetooth and a secure context (HTTPS or localhost): Chrome, Edge, and Opera on desktop and Android. Safari and Firefox do not support it, on any platform. Check InstaxPrinter.isSupported() before offering the feature.

Notes

• A freshly loaded pack has a black cover sheet on top. Until it is out, print fails with printer-error and status 0xb2. Call ejectFilmCover() once — but only then, since it ejects a sheet and burns a real shot if the cover is already gone. The cover does not decrement the shot counter.
• Only one image is held by the printer at a time; print uploads then prints.
• There is no "ejection finished" notification in the protocol. print waits a fixed 15 s per copy — tune with ejectDelay.
• A refused transfer is retried with a slower fragment cadence before failing.
• Unverified on hardware beyond INSTAX mini Link. Reports for square and wide welcome.

Development

npm install
npm test          # 94 unit tests against a fake printer, no hardware needed
npm run typecheck
npm run build
npm run example   # demo app at localhost:5174, needs a real printer

License

MIT — see LICENSE.