How To Choose The Right File Uploader For Your Marketplace

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A file uploader is an essential component of any online marketplace platform. It allows sellers to easily upload product images, documents, videos, and other files to list their items for sale. Choosing the right file uploader can have a big impact on the usability and security of your marketplace. Here’s how to select the best file uploader for your needs.

Key features to look for in a file uploader

You cannot just select a CDN provider randomly. You need to consider whether it is offering what you need or not. When evaluating file uploaders, there are several key features you should consider. Here are they:

File size limits

The file uploader for marketplaces should support common image sizes like 5-10MB for product photos. For documents, aim for around 50MB, while video files tend to be much larger at 100MB+. Setting appropriate size limits prevents performance issues when uploading and downloading files.

max file size

It's important to do research on the types of files your users will need to upload for your particular marketplace. Analyze competitors and similar sites to see what file sizes they support. You can also survey potential users directly to understand their requirements.

Set realistic limits based on expected usage patterns. Images for e-commerce products generally don't need to be larger than 10MB. But for high resolution photos, bump the limit to 20-30MB. Similarly, increase the document limit to 100MB or more if users need to upload large presentations, manuals, etc.

Supported file types

At a minimum, the file uploader should handle common image formats like JPG, PNG and GIF. It should also support PDFs for documents and MP4 for videos. Additional types like DOCX/XLSX for Microsoft Office files can be useful too. Restricting allowed formats reduces security risks.

Research the primary file types your users will need to upload and ensure full support for those. For images, also include high resolution formats like TIFF and RAW. Enable Photoshop PSDs if your users are graphic designers. For documents, add ODT, DOC and other word processing formats based on research.

However, balance openness with security. Obscure, proprietary or executable file types increase the risk of malware uploads. Either disallow those outright or scan them thoroughly before allowing access.

Drag and drop support

An uploader with drag and drop allows sellers to simply drag files from their desktop and drop onto the upload widget, saving clicks. This makes the process more user-friendly compared to needing to browse and select files to upload.

Drag and drop upload dramatically improves user experience on desktop devices by reducing the number of steps needed. Users can grab any file easily and quickly drop it for uploading without having to navigate folder structures.

file uploader drag and drop

Make the drag and drop target zone clearly visible on the page. As the user drags the file over it, change the style to indicate they can drop. Display a message like "Drop file here" for confirmation. So, an ideal file uploader needs to be reliable and fast with drag and drop support.

Progress bars

Large files can take significant time to upload, so showing progress bars keeps the user informed if the upload is proceeding smoothly. It also indicates how long they may need to wait for it to complete.

Progress indicators are vital for large file uploads exceeding 50MB. Without them, users may abandon the process if it seems stuck with no confirmation.

Implement progress bars using either determinate ones with percentages or indeterminate loading spinners for unknown durations. Show progress immediately to indicate the upload has started.

Image editing tools

On-the-fly image editing tools like cropping, resizing and filters allow sellers to optimize their images before uploading. This enables them to prepare listings faster.

Integrated image editing empowers marketplace sellers to easily improve their product photos. Offer user-friendly tools without needing desktop software skills.

Provide cropping to remove unnecessary parts of images like backgrounds. A resize option creates multiple sizes for thumbnails and previews. Basic filters alter brightness, contrast and saturation.

Multiple file uploads

Allowing multiple files to be selected and uploaded together speeds up the uploading process for sellers. This capability streamlines adding all assets associated with a product listing in one go.

Multiple file selection simplifies workflows for sellers listing products requiring several images or documents. Avoid needing to upload one file at a time.

Implement a multiple attribute on the file input element to permit selecting several files. Display the number of files chosen to confirm for the user. When users add files, show thumbnail previews of each selected file. Give an option to remove specific files from the selection.

Cloud storage integrations

Integration with cloud storage services like Google Drive and Dropbox enables users to select files directly from those sources. This provides flexibility to upload files from various locations.

Integrating with widely used cloud storage platforms avoids requiring users to download files to their local devices before uploading. Streamline the process with direct selection from cloud accounts.

Follow the OAuth protocol to request restricted access to the user's cloud storage instead of full account permissions. Scopes should be limited to reading files only.

Security considerations for file uploaders

Since sensitive information is often exchanged on online marketplaces, you need to check if a CDN provider you consider fulfills network and security checkbox:

Encrypted transfers

Uploaded files should be transferred over secure HTTPS connections to prevent interception or tampering of data. Unencrypted HTTP should not be allowed under any circumstances.

SSL certification

Use HTTPS with TLS 1.2 or higher for all connections throughout the application, not just the uploader. HTTP provides no protection of data from intermediaries.

Redirect HTTP access attempts to HTTPS. Register an HTTPS certificate from a trusted commercial CA like DigiCert or Let’s Encrypt. Enforce security headers like HTTP Strict Transport Security (HSTS) to mandate HTTPS usage at all times when possible. This prevents accidental HTTP usage.

File scanning

Scan files for malware before making them available for download. This step is essential to protect user devices from infection via tainted files. Use antivirus software or sandboxing techniques.

Integrate with security services like VirusTotal to scan files and check for any known threats flagged by multiple engines. Automate submission and analysis of results.

Access controls

Implement access controls so users can only access their own uploaded files. Set permissions to prevent unauthorized access to other's files. This maintains privacy and security.

Store files associated with the user IDs which uploaded them. Verify the accessing user ID matches before allowing downloads or edits. Use expiring pre-signed URLs for sharing files instead of public links. These grant time-limited access to files which cannot be easily propagated further.

Secure configuration

Securely configure the libraries/services used for file uploads according to best practices. Keep them updated regularly to incorporate latest security patches. Closely follow vendor security guidelines for whichever file storage service you utilize like Amazon S3, Azure Blob Storage, etc.

For open source libraries, check sites like for known vulnerabilities and patch appropriately or switch affected versions immediately. Disable insecure default configurations in libraries/services and enable recommended security features compatible with your stack.

Ease of integration

To ensure a smooth rollout, the file uploading widget should:

Work across frameworks

Easily integrate with common web frameworks like React, Angular, Vue.js etc. Write platform-agnostic code to support multiple frontend stacks.


Structure code in a modular fashion without extensive dependencies on specific frameworks. Stick to vanilla JavaScript for core uploading functionality.

Provide adapters for integrating with different frameworks like React components, Angular directives etc rather than duplicating code.

Provide client libraries

Include API client libraries for languages like Python, Java, JavaScript to simplify integration on the backend. Reduce dev time and effort.

In addition to frontend uploading widgets, provide corresponding client libraries for server-side integration.

Have a modular layered architecture separating core file management logic from platform-specific adapters for each language/framework.

Enable customizations

Allow styling tweaks via CSS and customization of behavior through events/callbacks. This helps match the file uploader to your marketplace's look. Make component markup semantic and standards-compliant to enable easy styling. Provide CSS hooks like classes and data attributes for common tweaks.

Responsive design

The widget should work smoothly across desktop and mobile devices to maintain consistency. Mobile usage is increasing so mobile-friendliness is a must. Use relative units like rem, em for element dimensions so they scale appropriately on different viewport sizes. Avoid fixed pixels.

Web development

Implement fluid layouts via Flexbox, CSS Grid and other modern techniques for flexible resizing and wrapping. Support responsive breakpoints. Listen for orientation change and resize events. Reactively adapt UI and web design for optimum usability as the available screen area changes.


By keeping these features and considerations in mind when evaluating file uploaders for your online marketplace platform, you can make the right choice for your needs.

Focus on usability, security and ease of integration during your assessment process. This will lead to a seamless experience for sellers and buyers during the critical file uploading and downloading workflows.

About the author 

Peter Keszegh

Most people write this part in the third person but I won't. You're at the right place if you want to start or grow your online business. When I'm not busy scaling up my own or other people' businesses, you'll find me trying out new things and discovering new places. Connect with me on Facebook, just let me know how I can help.

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