How to upload chunked files in MFT using Powershell and REST API

Overview

This article explains how to upload files to OPSWAT MetaDefender Managed File Transfer using PowerShell and the REST API with chunked upload.

It covers:

• Authentication

• Transfer group creation

• File initialization

• Chunked upload

• Transfer finalization

✅ Prerequisites

• Access to MetaDefender MFT API endpoint

• Valid username and password

• PowerShell 5.1+ or PowerShell 7+

• Network access to:

📂 File Preparation

Ensure the file exists locally:

🔐 Credentials File Format

Create a file named:

With content:

🔄 Workflow Summary

The upload process follows this sequence:

1. Authenticate → token

2. Create transfer group → group_id

3. Initialize file → file_id

4. Upload file in chunks

5. Close file transfer

6. Close group transfer

💻 PowerShell Script

(Place your cleaned-up version here — remove debug clutter and fix issues before publishing)

👉 Important: Include only:

• final working version

• comments explaining each step

⚙️ Key Configuration Parameters

📦 Chunk Upload Logic Explained

• File is read in fixed-size buffers

• Each chunk is sent with:

  • file_id

  • group_id

  • chunk_offset

• Offset increases after each upload

This prevents:

• Memory issues

• File corruption

• Large upload failures

✅ Validation

After execution, you should see:

❗ Troubleshooting

🔴 Authentication fails

• Verify credentials format

• Confirm encoding method (CRLF vs username:password)

🔴 File transfer fails on close

• Check file_checksum

• Ensure hash matches server expectation:

🔴 Chunk upload errors

• Verify:

  • chunk_offset correctness

  • chunk size (try reducing to 4MB)

• Check network stability

🔴 File corruption

Ensure buffer is trimmed:

🔐 Security Considerations

• Do not store plaintext passwords in production

• Use:

  • Windows Credential Manager

  • Secure vault solutions

• Always use HTTPS

🚀 Best Practices

• Use retry logic for chunk uploads

• Log all API responses

• Validate checksum after upload

• Tune chunk size based on network

Download: MFT-chunkupload