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kv file upload

…upload some binary files, or some cute cat and dog images and photos.

Take file, save it as an arrayBuffer and put the mime type into Cloudflare Worker's KV metadata field.

the example below takes a GET request with the query string image to retrieve the data from KV (including the metadata as content-type) and takes a POST request against the /upload path. you can upload files like so with curl:

curl -F file=@image.png

and fetch it like so then in your browser:

async function handleRequest(request, env) {
  const { searchParams, pathname } = new URL(request.url)
  let image = searchParams.get('image')

  if (image) {
    const img = await env.images.getWithMetadata(image, { type: 'arrayBuffer' })
    return new Response(img.value, { headers: { 'content-type': img.metadata.filetype } })

  if (pathname === '/upload' && request.method === 'POST') {
    const formData = await request.formData()
    const file = formData.get('file')
    await env.images.put(, await file.arrayBuffer(), { metadata: { filetype: file.type } })
    return new Response(JSON.stringify({ name:, type: file.type, size: file.size }))

export default {
  async fetch(request, env) {
    try {
      return await handleRequest(request, env)
    } catch (e) {
      return new Response(e.message)

large file upload

here's an example function to upload large bits of files, the whole body without running into a timeout or anything like that. Keep in mind that the maximum file size is still limited by whatever MB/GB is set to your account.

export async function putFile(request: Request, env: any): Promise<Response> {
  const contentType = request.headers.get('content-type')
  const filename = crypto.randomUUID()

  if (request.method === 'POST') {
    try {
      await env.bucket.put(filename, request.body, {
        httpMetadata: {
          contentType: contentType,
      return new Response(JSON.stringify({ success: true, filename: filename }))
    } catch (error) {
      return new Response(JSON.stringify({ success: false, message: 'could not upload file', error: error }))

how to upload this with curl then, the important bit is the Transfer-Encoding: chunked, and for large files or low-memory systems you need to use -T for uploading since --data-binary would load the whole file into memory. Also, set the content-type or get it through other means from your code:

curl -H "Transfer-Encoding: chunked" -H "content-type: video/mp4" --data-binary @example.mp4
curl -H "Transfer-Encoding: chunked" -H "content-type: video/mp4" -T example.mp4 https://example.comv/r2/upload