Upload media or NFC data

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/v1/sessions/{id}/media

Uploads an image file or collected NFC data for a specific session ID

When to use this endpoint

  • Use this endpoint to programmatically upload images to a verification session when using the API-based integration (not SDK)
  • Use this endpoint to upload previously collected NFC data for sessions where epassport has been used
  • If using the Veriff SDK, media upload is handled automatically within the SDK flow and this endpoint is not needed.

Common scenarios include:

  • Uploading document photos captured via your own interface
  • Submitting selfie images for face verification
  • Providing proof of address document images
  • Uploading generic documents for verification
  • Uploading collected NFC data for session verification

Request body content

Image upload
  • The image file is defined as base64 encoded image string inside a JSON body object
  • To avoid issues with upload, keep the file smaller than:
    • Image files: 24MB in base64 encoding (approx 17MB in image files format)
    • PDFs: 20 MB in pdf format
    • Make sure the longer side of the uploaded image is max 1920px

The request must include an image object containing:

  • context: what type of image is being uploaded (e.g., document-front, document-back, selfie). See Context types article for more info.
  • content: base64-encoded image data with data URI scheme
  • timestamp: when the image was captured (optional)

Supported image formats:

  • .jpg
  • .jpeg
  • .png
  • .heif
  • .heic
  • .webp
  • .pdf
NFC data upload
  • The NFC data object must contain com, sod, dg1 and dg2 data as base64-encoded strings in the request body.

Response data

  • Successful uploads return metadata about the uploaded media including:

    • Unique media ID for reference
    • Media type and context
    • File size and mimetype (format of the media file, see here for more info)
    • Download URL for accessing the uploaded image
    • sessionId the media belongs to
  • The timestamp field in the response is deprecated and always returns null.

Implementation notes

  • Only one image/data file can be uploaded with one request
  • Make sure that you upload all the images/NFC data before setting the status to "submitted" using the PATCH /sessions/ endpoint. If you try to upload media/data after you have submitted the session, you may encounter the 409 - conflict error.
  • For image uploads:
    • the same context can be uploaded multiple times (e.g., for retries)
    • base64 content should include the data URI scheme prefix (e.g., data:image/jpeg;base64,)
    • Maximum file size limits may apply depending on integration configuration
  • This endpoint requires session-level HMAC signature authentication
  • Always ensure that you use the correct API URL to send requests. See the API URL section for more info.
  • The order of parameters in the real API response can differ from the order you see in this documentation. This is expected and part of the Backwards compatible changes requirements.

Additional info

Improved fraud detection (image uploads)
  • Veriff strongly recommends you upload several images per context (e.g. face, document-front, document-back), to indicate liveness and improve fraud detection
  • Each image must be uploaded using a separate request
PDF support is not enabled by default (image uploads)
  • Veriff supports PDF file uploads for Identity and Document Verification (IDV) documents and Proof of Address (PoA) documents
  • Contact your Solutions Engineer before starting to upload PDF files
Identity and Document Verification feature (image uploads)
  • In IDV, document images can be uploaded in following configurations:
    • Two PDF files, where one file contains document front image and the other file contains document back image
    • Single PDF file, which has both document sides on different pages
    • Single PDF file, which has both document sides on single page
    • Veriff processes first 5 pages of uploaded PDF file. System removes empty pages from the PDF.
Proof of Address Verification (image uploads)
  • The file that is uploaded for Proof of Address flow must contain only one PoA document
  • Max document size is 20MB
Header parameters
x-auth-client
stringRequired

Your integration's API key (occasionally referred to as the "Token", "API public key" or "Publishable key"). Required for all API requests.

You can find your API key in the Veriff Customer Portal > Settings > API keys.

Exampleyour-api-key
x-hmac-signature
stringRequired

Request body signed with the shared secret key. Required to authenticate the request sender.

Examplea1b2c3d4e5f6g7h8i9j0k1l2m3n4o5p6q7r8s9t0u1v2w3x4y5z6
Content-Type
stringRequired

Content type of the request body

Valid values[ "application/json" ]
Exampleapplication/json
Path parameters
id
string (uuid) Required

Verification session ID.

Examplef04bdb47-d3be-4b28-b028-a652feb060b5
Body parameters
media_document_front

Standard document front side upload with base64-encoded JPEG image

{
  "image": {
    "context": "document-front",
    "content": "data:image/jpeg;base64,/9j/4AAQSkZJRgABAQEAYABgAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQNDAsLDBkSEw8UHRofHh0aHBwgJC4nICIsIxwcKDcpLDAxNDQ0Hyc5PTgyPC4zNDL/2wBDAQkJCQwLDBgNDRgyIRwhMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjL/wAARCAABAAEDASIAAhEBAxEB/8QAFQABAQAAAAAAAAAAAAAAAAAAAAv/xAAUEAEAAAAAAAAAAAAAAAAAAAAA/8QAFQEBAQAAAAAAAAAAAAAAAAAAAAX/xAAUEQEAAAAAAAAAAAAAAAAAAAAA/9oADAMBAAIRAxEAPwA/AAAA",
    "timestamp": "2025-01-01T10:00:00Z"
  }
}
media_document_back

Document back side upload with base64-encoded PNG format

{
  "image": {
    "context": "document-back",
    "content": "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNk+M9QDwADhgGAWjR9awAAAABJRU5ErkJggg==",
    "timestamp": "2025-01-01T10:00:15Z"
  }
}
media_selfie_face

Face verification selfie upload, base64-encoded JPEG file

{
  "image": {
    "context": "face",
    "content": "data:image/jpeg;base64,/9j/4AAQSkZJRgABAQEAYABgAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQNDAsLDBkSEw8UHRofHh0aHBwgJC4nICIsIxwcKDcpLDAxNDQ0Hyc5PTgyPC4zNDL/2wBDAQkJCQwLDBgNDRgyIRwhMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjL/wAARCAABAAEDASIAAhEBAxEB/8QAFQABAQAAAAAAAAAAAAAAAAAAAAv/xAAUEAEAAAAAAAAAAAAAAAAAAAAA/8QAFQEBAQAAAAAAAAAAAAAAAAAAAAX/xAAUEQEAAAAAAAAAAAAAAAAAAAAA/9oADAMBAAIRAxEAPwA/AAAA",
    "timestamp": "2025-01-01T10:01:00Z"
  }
}
media_proof_of_address

Proof of address document upload (utility bill, bank statement, etc.), base64-encoded JPEG file

{
  "image": {
    "context": "address-front",
    "content": "data:image/jpeg;base64,/9j/4AAQSkZJRgABAQEAYABgAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQNDAsLDBkSEw8UHRofHh0aHBwgJC4nICIsIxwcKDcpLDAxNDQ0Hyc5PTgyPC4zNDL/2wBDAQkJCQwLDBgNDRgyIRwhMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjL/wAARCAABAAEDASIAAhEBAxEB/8QAFQABAQAAAAAAAAAAAAAAAAAAAAv/xAAUEAEAAAAAAAAAAAAAAAAAAAAA/8QAFQEBAQAAAAAAAAAAAAAAAAAAAAX/xAAUEQEAAAAAAAAAAAAAAAAAAAAA/9oADAMBAAIRAxEAPwA/AAAA",
    "timestamp": "2025-01-01T10:05:00Z"
  }
}
media_without_timestamp

Media upload without optional timestamp field

{
  "image": {
    "context": "document-front",
    "content": "data:image/jpeg;base64,/9j/4AAQSkZJRgABAQEAYABgAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQNDAsLDBkSEw8UHRofHh0aHBwgJC4nICIsIxwcKDcpLDAxNDQ0Hyc5PTgyPC4zNDL/2wBDAQkJCQwLDBgNDRgyIRwhMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjIyMjL/wAARCAABAAEDASIAAhEBAxEB/8QAFQABAQAAAAAAAAAAAAAAAAAAAAv/xAAUEAEAAAAAAAAAAAAAAAAAAAAA/8QAFQEBAQAAAAAAAAAAAAAAAAAAAAX/xAAUEQEAAAAAAAAAAAAAAAAAAAAA/9oADAMBAAIRAxEAPwA/AAAA"
  }
}
nfcDocuments_data_upload

NFC data upload with base64-encoded strings for com, sod, dg1 and dg2 fields

{
  "nfcDocuments": {
    "com": "SGVsbG8sIHRoaXMgaXMgY29tIGRhdGEgZm9yIE5GQyB1cGxvYWQu...",
    "sod": "VGhpcyBpc24ndCBhIHJlYWwgbmZjIHN0cmluZyBidXQgcmF0aGVyIGEgc2ltdWxhdGlvbi4=...",
    "dg1": "RGF0YSBmb3IgZGcxIGZpZWxkIGluIEVQYXNz...",
    "dg2": "dRGF0YSBmb3IgZGcyIGZpZWxkIGluIEVQYXNz..."
  }
}
Expand All
OneOf
MediaUploadRequest
object (MediaUploadRequest)
image
object (MediaUploadImage)
context
string Required

Context of the uploaded media, i.e., what the uploaded image was taken of.

Veriff captures multiple images, therefore the image with the -pre suffix is the first one, and the one without is the second image.

See Context types article for more info.

Exampledocument-front
content
string (base64) Required

The media file to be uploaded, as base64 encoded image (.jpg, .jpeg, .png, .heif, .heic, .webp and .pdf formats are supported).

Exampledata:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAA+.../9fgAEAKcxisFjVfn0AAAAASUVORK5CYII=
timestamp
string (YYYY-MM-DDTHH:MM:SS+Z)

Timestamp of the upload as combined ISO 8601 date and time in UTC, YYYY-MM-DDTHH:MM:SS+Timezone Offset.

Example2020-01-01T00:00:00.000Z
NfcDocumentsUploadRequest
object (NfcDocumentsUploadRequest)
nfcDocuments
object (NfcDocuments) Required
com
string (base64) Required

Base64 encoded content of the COM file retrieved from the NFC chip of the document.

COM file contains info about the version of the data structure and a list of which Data Groups (DGs) are actually available on that specific document.

ExampleSGVsbG8sIHRoaXMgaXMgY29tIGRhdGEgZm9yIE5GQyB1cGxvYWQu...
sod
string (base64) Required

Base64 encoded content of the SOD file retrieved from the NFC chip of the document.

SOD file contains the digital signature of the data read from the NFC chip, ensuring its authenticity and integrity.

ExampleVGhpcyBpc24ndCBhIHJlYWwgbmZjIHN0cmluZyBidXQgcmF0aGVyIGEgc2ltdWxhdGlvbi4=...
dg1
string (base64) Required

Base64 encoded content of the DG1 file retrieved from the NFC chip of the document.

DG1 file contains info found in the physical Machine Readable Zone (MRZ) of the documen, typically including the personal data of the document holder, such as name, date of birth, and document number.

ExampleRGF0YSBmb3IgZGcxIGZpZWxkIGluIEVQYXNz...
dg2
string (base64) Required

Base64 encoded content of the DG2 file retrieved from the NFC chip of the document.

DG2 file contains the biometric data of the document holder, such as their facial image.

ExampleRGF0YSBmb3IgZGcyIGZpZWxkIGluIEVQYXNz...
Responses
200

Media uploaded successfully.

Headers
Content-Type
string
Response content type.
Valid values[ "application/json" ]
x-auth-client
string
API key echoed back in response.
x-hmac-signature
string
Response body signed with the shared secret key. Required to authenticate the response sender.
document_front_success

Document front uploaded successfully

{
  "status": "success",
  "image": {
    "id": "d69a07cf-4434-4d36-be6c-d22af7dc01fb",
    "name": "document-front",
    "context": "document-front",
    "timestamp": null,
    "size": 245678,
    "mimetype": "image/jpeg",
    "url": "https://exampleURL.com/v1/media/d69a07cf-4434-4d36-be6c-d22af7dc01fb",
    "sessionId": "f04bdb47-d3be-4b28-b028-a652feb060b5"
  }
}
face_upload_success

Selfie uploaded successfully

{
  "status": "success",
  "image": {
    "id": "a1b2c3d4-e5f6-4g7h-8i9j-0k1l2m3n4o5p",
    "name": "face",
    "context": "face",
    "timestamp": null,
    "size": 189234,
    "mimetype": "image/jpeg",
    "url": "https://exampleURL.com/v1/media/a1b2c3d4-e5f6-4g7h-8i9j-0k1l2m3n4o5p",
    "sessionId": "f04bdb47-d3be-4b28-b028-a652feb060b5"
  }
}
proof_of_address_success

Proof of Address document uploaded successfully

{
  "status": "success",
  "image": {
    "id": "6q7r8s9t-0u1v-4w3x-4y5z-6a1b2c3d4e5f",
    "name": "address-front",
    "context": "address-front",
    "timestamp": null,
    "size": 512890,
    "mimetype": "image/jpeg",
    "url": "https://exampleURL.com/v1/media/6q7r8s9t-0u1v-4w3x-4y5z-6a1b2c3d4e5f",
    "sessionId": "f04bdb47-d3be-4b28-b028-a652feb060b5"
  }
}
nfc_data_upload_success

NFC data uploaded successfully

{
  "status": "success",
  "nfcDocument": {
    "id": "908d041f-e66e-47de-9664-0950a201fd85",
    "name": "document-nfc",
    "context": "document-nfc",
    "timestamp": null,
    "size": 29584,
    "mimetype": "application/octet-stream",
    "url": "https://exampleURL.com/v1/media/908d041f-e66e-47de-9664-0950a201fd85",
    "sessionId": "86c71df5-c163-4022-9c94-1fb6dc903a98"
  }
}
Expand All
OneOf
ImageUploadResponse
object (ImageUploadResponse)
status
string

Upload status.

Examplesuccess
image
object (VerificationSessionImageUpload)
id
string (uuid)

UUID v4 which identifies the uploaded media.

Exampled69a07cf-4434-4d36-be6c-d22af7dc01fb
name
string

Name which identifies the uploaded media.

Valid values[ "address-front", "document-and-face", "document-and-face-pre", "document-back", "document-back-barcode", "document-back-barcode-pre", "document-back-pre", "document-back-qrcode", "document-back-qrcode-pre", "document-front", "document-front-face-cropped", "document-front-pre", "document-front-qrcode", "document-front-qrcode-pre", "face", "face-cropped", "face-nfc", "face-pre", "face-reference", "registry-face" ]
Exampledocument-front
context
string

Context type of the uploaded media.

See Context types article for more info.

Valid values[ "address-front", "document-and-face", "document-and-face-pre", "document-back", "document-back-barcode", "document-back-barcode-pre", "document-back-pre", "document-back-qrcode", "document-back-qrcode-pre", "document-front", "document-front-face-cropped", "document-front-pre", "document-front-qrcode", "document-front-qrcode-pre", "face", "face-cropped", "face-nfc", "face-pre", "face-reference", "registry-face" ]
Exampledocument-front
timestamp
string Deprecated

Always returns None/null.

Example
size
number

Size of the uploaded media, in bytes.

Example12345.0
mimetype
string

File type of the uploaded media.

See Media file mimetypes article for more info.

Valid values[ "image/jpeg", "image/jpg", "image/png", "image/heif", "image/heic", "image/webp", "application/pdf" ]
Exampleimage/jpeg
url
string

Download URL of the media.

Examplehttps://exmpleURL.com/v1/media/d69a07cf-4434-4d36-be6c-d22af7dc01fb
sessionId
string

UUID v4 of the verification session the uploaded media belongs to.

Exampled69a07cf-4434-4d36-be6c-d22af7dc01fb
NfcUploadResponse
object (NfcUploadResponse)
status
string

Upload status.

Examplesuccess
nfcDocuments
object (NfcDocumentsUpload)
id
string (uuid)

UUID v4 which identifies the uploaded NFC data.

Example89e42557-0ac6-4307-a645-3c14aedfef1f
name
string

Name which identifies the uploaded NFC data.

Valid values[ "document-nfc" ]
Exampledocument-nfc
context
string

Context type of the uploaded NFC data.

Valid values[ "document-nfc" ]
Exampledocument-nfc
timestamp
string | null Deprecated

Always returns null.

Example
size
integer

Size of the uploaded NFC data, in bytes.

Example29584
mimetype
string

File type of the uploaded NFC data.

Exampleapplication/octet-stream
sessionId
string (uuid)

UUID v4 of the verification session the uploaded NFC data belongs to.

Example504c4d55-aa1e-47d1-a4e3-06ad0a51e564
url
string

Download URL of the NFC data.

Examplehttps://exampleURL.com/v1/media/89e42557-0ac6-4307-a645-3c14aedfef1f
400

Bad request

Headers
Content-Type
string
Response content type.
Valid values[ "application/json" ]
x-auth-client
string
API key echoed back in response.
x-hmac-signature
string
Response body signed with the shared secret key. Required to authenticate the response sender.
bad_request

Request failed

{
  "status": "fail",
  "code": "1101",
  "message": "Validation failed"
}
invalid_nfc_data

Invalid NFC format

The request is missing required data groups or the base64 format is incorrect.

{
  "status": "fail",
  "code": "1410",
  "error": "NFC data format is invalid or missing required fields"
}
object
status
string
Valid values[ "fail" ]
Examplefail
code
string
Example1101
message
string
ExampleValidation failed
401

Unauthorized

Headers
Content-Type
string
Response content type.
Valid values[ "application/json" ]
x-auth-client
string
API key echoed back in response.
missing_api_key

Missing API key

Request failed because x-auth-client header is missing

{
  "status": "fail",
  "code": "1101",
  "message": "Mandatory X-AUTH-CLIENT header containing the API key is missing from the request."
}
object
status
string
Valid values[ "fail" ]
Examplefail
code
string
Example1101
message
string
ExampleMandatory X-AUTH-CLIENT header containing the API key is missing from the request.
404

Session not found

Headers
Content-Type
string
Response content type.
Valid values[ "application/json" ]
x-auth-client
string
API key echoed back in response.
x-hmac-signature
string
Response body signed with the shared secret key. Required to authenticate the response sender.
session_not_found

Request failed because session does not exist

{
  "status": "fail",
  "code": "1101",
  "message": "Resource not found"
}
object
status
string
Valid values[ "fail" ]
Examplefail
code
string
Example1101
message
string
ExampleResource not found
413

Bad request

Headers
Content-Type
string
Response content type.
Valid values[ "application/json" ]
x-auth-client
string
API key echoed back in response.
x-hmac-signature
string
Response body signed with the shared secret key. Required to authenticate the response sender.
nfc_payload_too_large

Payload size exceeded

The combined NFC data exceeds the 500KB limit.

{
  "status": "fail",
  "code": "1412",
  "error": "NFC payload too large. Maximum size is 500KB"
}
object
status
string
Valid values[ "fail" ]
Examplefail
code
string

Veriff-specific error code for NFC failures.

Example1410
error
string

Detailed error message.

ExampleNFC data format is invalid or missing required fields
500

Internal server error

Headers
Content-Type
string
Response content type.
Valid values[ "application/json" ]
x-auth-client
string
API key echoed back in response.
x-hmac-signature
string
Response body signed with the shared secret key. Required to authenticate the response sender.
server_error

Internal server error

Request failed due to an internal server error

{
  "status": "fail",
  "code": "1101",
  "message": "Something went wrong"
}
object
status
string
Valid values[ "fail" ]
Examplefail
code
string
Example1101
message
string
ExampleSomething went wrong

Media compression support info

This endpoint accepts compressed request bodies with Content-Encoding: gzip or Content-Encoding: deflate. Because media uploads carry base64-encoded images inside JSON, compression typically reduces payload size by 25–35%, lowering bandwidth usage and upload latency.

Request-body compression is a transport optimization, it does not change the signing contract. Your signature is always computed over the uncompressed JSON body. The server decompresses the payload before validating the signature.

No configuration changes are required for the integration to start using this feature. To use compression, include exactly one of these Content-Encoding values in your request:

  • gzip (recommended)
  • deflate

Combined values such as gzip, deflate or deflate, gzip are not supported. br is not supported on this endpoint.

 Operation order

Getting the order right is critical. The signature must cover the uncompressed payload, and the compressed payload must decompress back to the exact bytes that were signed.

  1. Build the JSON payload (same as today)
  2. Serialize the JSON to bytes
  3. Compute the signature over the serialized bytes ← sign BEFORE compressing
  4. Compress the serialized bytes (gzip or deflate)
  5. Send the compressed bytes with the matching Content-Encoding value

If you compress first and then sign the compressed bytes, signature validation will fail.

Request headers

  • x-auth-client = your API key
  • x-hmac-signature = Lowercase hex HMAC-SHA256 (64 chars, no prefix) of the uncompressed JSON body
  • Content-type = application/json
  • Content-Encoding = gzip (recommended) or deflate

Code examples

The examples below use gzip. If you use deflate, keep the same signing flow and set Content-Encoding: deflate with deflate-compressed bytes.

Python Code Example

Python

Text
import base64
import gzip
import hashlib
import hmac
import json
import requests

API_KEY = "your-api-key"
SHARED_SECRET = "your-shared-secret"
SESSION_ID = "your-session-id"
BASE_URL = "https://stationapi.veriff.com"

# Read and encode image
with open("document_front.jpg", "rb") as f:
    image_bytes = f.read()
b64_content = base64.b64encode(image_bytes).decode("utf-8")

# Step 1–2: Build and serialize the JSON payload
payload = {
    "image": {
        "context": "document-front",
        "content": f"data:image/jpeg;base64,{b64_content}",
    }
}
payload_bytes = json.dumps(payload, separators=(",", ":")).encode("utf-8")

# Step 3: Sign the UNCOMPRESSED payload
signature = hmac.new(
    SHARED_SECRET.encode("utf-8"),
    payload_bytes,
    hashlib.sha256,
).hexdigest()

# Step 4: Compress
compressed = gzip.compress(payload_bytes)

# Step 5: Send with Content-Encoding: gzip
response = requests.post(
    f"{BASE_URL}/v1/sessions/{SESSION_ID}/media",
    data=compressed,                        # raw bytes, not json=
    headers={
        "X-AUTH-CLIENT": API_KEY,
        "X-HMAC-SIGNATURE": signature,
        "Content-Type": "application/json",
        "Content-Encoding": "gzip",
    },
)
print(response.status_code, response.json())

Node Code Example

Node.js

Text
const crypto = require('crypto');
const fs = require('fs');
const zlib = require('zlib');
const https = require('https');

const API_KEY = 'your-api-key';
const SHARED_SECRET = 'your-shared-secret';
const SESSION_ID = 'your-session-id';
const BASE_URL = 'stationapi.veriff.com';

// Read and encode image
const imageBytes = fs.readFileSync('document_front.jpg');
const b64Content = imageBytes.toString('base64');

// Step 1–2: Build and serialize the JSON payload
const payload = {
  image: {
    context: 'document-front',
    content: `data:image/jpeg;base64,${b64Content}`,
  },
};
const payloadBytes = Buffer.from(JSON.stringify(payload));

// Step 3: Sign the UNCOMPRESSED payload
const signature = crypto
  .createHmac('sha256', SHARED_SECRET)
  .update(payloadBytes)
  .digest('hex');

// Step 4: Compress
const compressed = zlib.gzipSync(payloadBytes);

// Step 5: Send with Content-Encoding: gzip
const req = https.request(
  {
    hostname: BASE_URL,
    path: `/v1/sessions/${SESSION_ID}/media`,
    method: 'POST',
    headers: {
      'X-AUTH-CLIENT': API_KEY,
      'X-HMAC-SIGNATURE': signature,
      'Content-Type': 'application/json',
      'Content-Encoding': 'gzip',
      'Content-Length': compressed.length,
    },
  },
  (res) => {
    let body = '';
    res.on('data', (chunk) => (body += chunk));
    res.on('end', () => console.log(res.statusCode, body));
  }
);
req.write(compressed);
req.end();

Common mistakes

Signing the compressed bytes. The most common integration error. If you compress first and then compute the HMAC over the compressed output, the server will reject the request with a 401. Always sign the uncompressed JSON body.

Encoding/header mismatch. If you send Content-Encoding: gzip or Content-Encoding: deflate but the body is not encoded accordingly, the request fails with a 400. If you are not compressing, omit the Content-Encoding header.

Using json= in your HTTP library with compressed bytes. When sending compressed data, pass compressed bytes as a raw body (data= in Python requests, content= in httpx), not as a JSON parameter. Setting json= causes the HTTP library to re-serialize the payload, which defeats compression and breaks the signature.

Double compression. Do not set Content-Encoding if your HTTP client or proxy is already compressing the request transparently. If in doubt, check the outbound request body and Content-Encoding header.

Using unsupported or combined encodings. Supported values are exactly gzip or deflate. Combined values (for example, gzip, deflate) and other encodings (for example, br) fail with a 415 http error.




Document Versioning

Changelog

Date

Description

Mar 24, 2026

"Media compression support info" section added

Mar 20, 2026

NFC data upload info and examples added

Mar 9, 2026

Documentation updated: parent categories rearranged, intro section expanded, request and response examples added

Nov 26, 2025

Added the "Note about improved fraud detection" section

Oct 2, 2025

vrf- headers removed from response headers

Aug 6, 2025

Response headers added

May 2, 2025

Updated the info about PDF files support for Proof of Address Verification flow to match the logic of Proof of Address Verification solution

Note about multiple PDF uploads for PoA solution moved to the legacy Proof of Address Extraction documentation as it is only applicable for that flow.

Apr 21, 2025

Added a note about the max length of the longer side of an image

Mar 12, 2025

Documentation published