Uploading supporting documents using Pre-signed URLs

This guide explains how to request and use pre-signed URLs to upload supporting documents during corporate onboarding.

Document uploads apply to:

Corporate (onboarding-level) documents

Individual associate documents

Parent entity documents

Parent entity associate documents

All uploads follow the same two-stage process:

Request pre-signed URLs

Upload files directly using those URLs

1. Request pre-signed URLs

Sokin provides separate APIs depending on what type of document you are uploading. Each endpoint requires a specific identifier and returns pre-signed URLs tailored to that entity.

A) Corporate (Onboarding-Level) Documents

Endpoint
POST /corporates/documents

Use this endpoint to request upload URLs for corporate documents required during onboarding.

Typical document types

Certificate of Incorporation

Articles of Association

Due Diligence Bundle

Response structure

The response returns:

A list of pre-signed URLs (urls)

One URL per file requested

Each URL:

Is valid for 10 minutes

Allows one file upload

Accepts files up to 20 MB

B) Associate Documents (Individual)

Endpoint
POST /corporates/associates/documents

Use this endpoint to request upload URLs for associate identity and address verification documents.

Required inputs

associateId
The ID returned when the associate was created

idType
Valid values:

Passport

Driver’s License

Identity Card

SSN

Residence Permit

idContentType
application/pdf, pdf, or image

Optional fields may include:

idNumber

issuedCountry

idExpiryDate

addressType

addressContentType

documentName

Response structure

The response includes:

status

success

message

presignedResponse (contains upload details)

The system generates URLs based on the selected idType and addressType.

For example:

If idType = Passport, only a front image upload URL is generated.

Address proof URLs are generated only if addressType is provided and required.

Each URL:

Is valid for 10 minutes

Allows one upload

Accepts PDF or image files up to 20 MB

All files must be linked to a valid associateId.

C) Parent Entity Documents

Endpoint
POST /corporates/parent-entities/documents

Use this endpoint to request upload URLs for Parent Entity (corporate associate) documents.

Accepted document types

Certificate of Incorporation

Articles of Association

List of Directors

Structure Chart

Required inputs

corporateAssociateId
The ID returned when the Parent Entity was created

corporateExternalReference
To ensure correct linkage to the onboarding session

documentType

noOfDocuments (1–5 files)

contentType (application/pdf, pdf, or image)

Response structure

The response includes:

A list of pre-signed URLs (urls)

One URL per file requested

Each URL:

Is valid for 10 minutes

Allows one upload

Accepts files up to 20 MB

All files must be linked to a valid corporateAssociateId.

2. Upload files using pre-signed URLs

After receiving the pre-signed URLs, you must upload files directly to the storage service using those URLs.

For each URL:

Perform a POST request directly to the provided URL

Include all fields and parameters exactly as returned in the response

Attach the file to the file field

Ensure the file meets size and format requirements

Each URL:

Can only be used once

Will overwrite the previous file if reused

Expires after 10 minutes

A 204 No Content response indicates a successful upload.
A 400 Bad Request typically indicates the URL has expired.

If a URL expires, you must request a new one.

File requirements

All uploads must:

Be under 20 MB

Match the declared content type

Match the declared document type

Supported formats:

PDF

PNG

JPG

JPEG

ZIP (Due Diligence Bundle only)

Important considerations

Uploading files does not finalise onboarding.

All required documents must be uploaded before submission.

Missing or incorrectly uploaded documents may delay review and approval.

Document requirements vary based on the assigned due diligence model and ownership structure.

After document upload

Once all required documents are successfully uploaded:

Review onboarding completeness

Finalise the onboarding request

Monitor status updates during review

Refer to:

Finalise onboarding guide

Uploading supporting documents using Pre-signed URLs

1. Request pre-signed URLs#

A) Corporate (Onboarding-Level) Documents#

Response structure#

B) Associate Documents (Individual)#

Response structure#

C) Parent Entity Documents#

Response structure#

2. Upload files using pre-signed URLs#

File requirements#

Important considerations#

After document upload#

1. Request pre-signed URLs

A) Corporate (Onboarding-Level) Documents

Response structure

B) Associate Documents (Individual)

Response structure

C) Parent Entity Documents

Response structure

2. Upload files using pre-signed URLs

File requirements

Important considerations

After document upload