presigned-uploads

Presigned uploads

For files larger than about 50 MB, skip the base64-in-JSON body of

POST /v1/extract and use the three-step presigned-upload flow instead.

The client uploads bytes directly to object storage, then tells the API to

start processing.

When to reach for this

• Single file > 50 MB.
• Batch with aggregate body size > 100 MB.
• Bandwidth-constrained environments where double-encoding (base64 + TLS
• worker) wastes throughput.
• File already lives in S3 / GCS and you can stream rather than buffer.

The three steps

1. POST /v1/uploads/presign  → batch_id + per-file presigned PUT URLs
2. PUT <upload_url>          → upload each file's bytes directly
3. POST /v1/uploads/confirm  → start extraction, returns job_ids

Step 1 returns one upload_url per document. Step 3 cannot run until

every PUT in step 2 succeeds.

Step 1 — presign

curl -X POST https://api.kreuzberg.dev/v1/uploads/presign \
  -H "Authorization: Bearer $KREUZBERG_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "documents": [
      {"filename": "scan.pdf", "mime_type": "application/pdf"},
      {"filename": "report.docx", "mime_type": "application/vnd.openxmlformats-officedocument.wordprocessingml.document"}
    ],
    "config": {"output_format": "markdown"},
    "webhook": {"url": "https://hooks.example.com/x"}
  }'

Response

{
  "batch_id": "batch_550e8400-e29b-41d4-a716",
  "uploads": [
    {
      "job_id": "550e8400-...",
      "upload_url": "https://storage.googleapis.com/kreuzberg-dev-uploads/...",
      "object_key": "projects/abc123/uploads/550e8400-...",
      "method": "PUT",
      "expires_in_secs": 3600
    },
    {
      "job_id": "660e9400-...",
      "upload_url": "https://storage.googleapis.com/kreuzberg-dev-uploads/...",
      "object_key": "projects/abc123/uploads/660e9400-...",
      "method": "PUT",
      "expires_in_secs": 3600
    }
  ]
}

Keep the batch_id — you need it for step 3. URLs expire in 3600 seconds

(1 hour); upload before then.

Step 2 — PUT to each upload URL

The presigned URL is signed by Google Cloud Storage; PUT directly to it,

without an Authorization header. Set Content-Type to match the

mime_type declared in step 1:

curl -X PUT "<upload_url>" \
  -H "Content-Type: application/pdf" \
  --data-binary @scan.pdf

A successful upload returns 200 OK with no body. Do this for every

entry in uploads before moving on.

Step 3 — confirm

curl -X POST https://api.kreuzberg.dev/v1/uploads/confirm \
  -H "Authorization: Bearer $KREUZBERG_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"batch_id": "batch_550e8400-e29b-41d4-a716"}'

Response (202)

{
  "job_ids": ["550e8400-...", "660e9400-..."],
  "status": "processing"
}

These are the same job_id values returned in step 1's uploads array.

From here, the flow is identical to offloading-extraction — poll

GET /v1/jobs/{id} or wait for the webhook.

End-to-end curl example

#!/usr/bin/env bash
set -euo pipefail
API="https://api.kreuzberg.dev"
KEY="$KREUZBERG_API_KEY"
FILE="scan.pdf"

# 1. Presign
resp=$(curl -fsS -X POST "$API/v1/uploads/presign" \
  -H "Authorization: Bearer $KEY" \
  -H "Content-Type: application/json" \
  -d '{"documents":[{"filename":"'"$FILE"'","mime_type":"application/pdf"}]}')

batch_id=$(echo "$resp" | jq -r .batch_id)
upload_url=$(echo "$resp" | jq -r '.uploads[0].upload_url')

# 2. PUT
curl -fsS -X PUT "$upload_url" \
  -H "Content-Type: application/pdf" \
  --data-binary "@$FILE"

# 3. Confirm
curl -fsS -X POST "$API/v1/uploads/confirm" \
  -H "Authorization: Bearer $KEY" \
  -H "Content-Type: application/json" \
  -d '{"batch_id":"'"$batch_id"'"}' | jq .

Errors

| Status | Where | Cause |

|---|---|---|

| 400 | presign | Empty documents, bad MIME, missing filename. |

| 403 | PUT | URL expired (>1h since presign) or Content-Type mismatch. |

| 400 | confirm | One or more uploads missing in storage. |

| 401 | presign/confirm | Bad Bearer token. |

If confirm returns 400 complaining about a missing upload, retry the

PUT for that specific object_key — confirmation requires every file to

be present in storage first.

When not to use this

For files under ~5 MB, the JSON data field is simpler and lower-latency

(one round trip instead of three). See the offloading-extraction skill.