Upload one part of a chunked upload

curl --request PUT \
  --url 'https://blob.squarecloud.app/v1/objects/chunked?upload=UPLOAD_TOKEN&part=1' \
  --header 'Authorization: YOUR_API_KEY' \
  --header 'Content-Type: application/octet-stream' \
  --data-binary '@./chunk-1.bin'

const PART_SIZE = 16 * 1024 * 1024;
const total = Math.ceil(file.size / PART_SIZE);

async function sendPart(n) {
  const body = file.slice((n - 1) * PART_SIZE, n * PART_SIZE);
  const params = new URLSearchParams({ upload: uploadToken, part: String(n) });
  const res = await fetch(`https://blob.squarecloud.app/v1/objects/chunked?${params}`, {
    method: 'PUT',
    headers: { Authorization: 'YOUR_API_KEY', 'Content-Type': 'application/octet-stream' },
    body,
  });
  if (res.status === 429 || res.status >= 500) return sendPart(n); // add a backoff in production
  if (!res.ok) throw new Error((await res.json()).code);
}

// 6 workers, each taking the next part number
let next = 1;
await Promise.all(Array.from({ length: 6 }, async () => {
  while (next <= total) await sendPart(next++);
}));

import requests

with open('./bigfile.bin', 'rb') as f:
    chunk = f.read(16 * 1024 * 1024)

response = requests.put(
    'https://blob.squarecloud.app/v1/objects/chunked',
    headers={'Authorization': 'YOUR_API_KEY', 'Content-Type': 'application/octet-stream'},
    params={'upload': upload_token, 'part': 1},
    data=chunk,
)

{
  "status": "success",
  "response": {
    "part": 1,
    "size": 16777216,
    "etag": "\"9bb58f26192e4ba00f01e2e7b136bbd8\""
  }
}

string

required

The API key for your account. You can find this in your account settings.

Chunked Part sends one part of an upload opened with Chunked Init. The body is the raw bytes of the part, not multipart/form-data. Part numbers run from 1 to 2048 and may be sent in any order. Re-sending a part with the same number replaces it, so a failed part can simply be retried. Every part except the last must have from 5 MB to 32 MB; the last one may be smaller. Send at most 6 parts in parallel per account: a seventh answers TOO_MANY_CONCURRENT_CHUNKS, and you retry that part once another finishes. With 6 in flight, 16 MB parts are a good default for a browser. This route has its own limit of 60 parts per 10 seconds and doesn’t consume the account-wide API budget, so a long upload can’t exhaust your API quota for the rest of the platform. Requires the blob:write scope, or the upload token that opened the upload, and an active plan.

Parameters

string

required

The upload token returned by Chunked Init.

number

required

The part number, from 1 to 2048.

binary

required

The raw part bytes (Content-Type: application/octet-stream).

Response

string

“success” if successful, “error” if not.

object

Show Toggle object

number

The part number stored.

number

The size of the part, in bytes.

string

The ETag of the part. Informational: Chunked Complete reads the part list on the server, so you never send it back.

curl --request PUT \
  --url 'https://blob.squarecloud.app/v1/objects/chunked?upload=UPLOAD_TOKEN&part=1' \
  --header 'Authorization: YOUR_API_KEY' \
  --header 'Content-Type: application/octet-stream' \
  --data-binary '@./chunk-1.bin'

const PART_SIZE = 16 * 1024 * 1024;
const total = Math.ceil(file.size / PART_SIZE);

async function sendPart(n) {
  const body = file.slice((n - 1) * PART_SIZE, n * PART_SIZE);
  const params = new URLSearchParams({ upload: uploadToken, part: String(n) });
  const res = await fetch(`https://blob.squarecloud.app/v1/objects/chunked?${params}`, {
    method: 'PUT',
    headers: { Authorization: 'YOUR_API_KEY', 'Content-Type': 'application/octet-stream' },
    body,
  });
  if (res.status === 429 || res.status >= 500) return sendPart(n); // add a backoff in production
  if (!res.ok) throw new Error((await res.json()).code);
}

// 6 workers, each taking the next part number
let next = 1;
await Promise.all(Array.from({ length: 6 }, async () => {
  while (next <= total) await sendPart(next++);
}));

import requests

with open('./bigfile.bin', 'rb') as f:
    chunk = f.read(16 * 1024 * 1024)

response = requests.put(
    'https://blob.squarecloud.app/v1/objects/chunked',
    headers={'Authorization': 'YOUR_API_KEY', 'Content-Type': 'application/octet-stream'},
    params={'upload': upload_token, 'part': 1},
    data=chunk,
)

{
  "status": "success",
  "response": {
    "part": 1,
    "size": 16777216,
    "etag": "\"9bb58f26192e4ba00f01e2e7b136bbd8\""
  }
}

Errors

Code	HTTP	When
`INVALID_UPLOAD_TOKEN`	400	The `upload` token is missing, malformed or not yours.
`INVALID_CHUNK_PART`	400	`part` is not an integer from 1 to 2048.
`EMPTY_CHUNK`	400	The body is empty.
`PERMISSION_DENIED`	401	The account has no active plan.
`UPLOAD_NOT_FOUND`	404	The upload was completed, aborted or expired.
`CHUNK_TOO_LARGE`	413	The part has more than 32 MB.
`FILE_TOO_LARGE`	413	With this part, the upload passes its size limit.
`TOO_MANY_CONCURRENT_CHUNKS`	429	6 parts are already in flight. Retry this part when one finishes.
`RATE_LIMITED`	429	More than 60 parts in 10 seconds.
`UPLOAD_FAILED`	500	The part failed. Retry it.

Blob SDK: blob.put() runs the whole chunked flow for files above 90 MiB

curl --request PUT \
  --url 'https://blob.squarecloud.app/v1/objects/chunked?upload=UPLOAD_TOKEN&part=1' \
  --header 'Authorization: YOUR_API_KEY' \
  --header 'Content-Type: application/octet-stream' \
  --data-binary '@./chunk-1.bin'

const PART_SIZE = 16 * 1024 * 1024;
const total = Math.ceil(file.size / PART_SIZE);

async function sendPart(n) {
  const body = file.slice((n - 1) * PART_SIZE, n * PART_SIZE);
  const params = new URLSearchParams({ upload: uploadToken, part: String(n) });
  const res = await fetch(`https://blob.squarecloud.app/v1/objects/chunked?${params}`, {
    method: 'PUT',
    headers: { Authorization: 'YOUR_API_KEY', 'Content-Type': 'application/octet-stream' },
    body,
  });
  if (res.status === 429 || res.status >= 500) return sendPart(n); // add a backoff in production
  if (!res.ok) throw new Error((await res.json()).code);
}

// 6 workers, each taking the next part number
let next = 1;
await Promise.all(Array.from({ length: 6 }, async () => {
  while (next <= total) await sendPart(next++);
}));

import requests

with open('./bigfile.bin', 'rb') as f:
    chunk = f.read(16 * 1024 * 1024)

response = requests.put(
    'https://blob.squarecloud.app/v1/objects/chunked',
    headers={'Authorization': 'YOUR_API_KEY', 'Content-Type': 'application/octet-stream'},
    params={'upload': upload_token, 'part': 1},
    data=chunk,
)

{
  "status": "success",
  "response": {
    "part": 1,
    "size": 16777216,
    "etag": "\"9bb58f26192e4ba00f01e2e7b136bbd8\""
  }
}

Get started

Objects

Chunked uploads

Account

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S3

Upload one part of a chunked upload

Parameters

Response

Errors

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​Errors

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Parameters

Response

Errors

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