How to Test Multipart File Uploads & Cloud Storage CDN in React Without an S3 Bucket

Building drag-and-drop file upload interfaces in React often hits a major hurdle during development: where do the files actually go?

Setting up AWS S3 pre-signed URLs or Cloudinary credentials just to test if your progress bar animates or if image thumbnails render properly is tedious. Worse, when you need to test edge cases—like uploading a 15MB file over a slow 3G connection, or handling unsupported file types (415 Unsupported Media Type)—mocking FormData requests in client-side code feels impossible.

Playground API provides a dedicated Multipart File Upload & Cloud Storage Sandbox (POST /api/v1/uploads and POST /api/v1/uploads/bulk) with simulated upload latency and CDN media URLs!

1. Uploading a Single File with FormData

Send standard multipart/form-data requests:

JSON Response:

2. Simulating Upload Latency & Progress Bars

To test your UI progress bars and loading spinners under real-world conditions, pass the _delay query parameter or X-Simulate-Delay header:

Playground API holds the connection and streams progress events before completing with the CDN asset metadata.

3. Bulk Uploads & Multi-File Validation

Need to test multi-file upload zones? Use POST /api/v1/uploads/bulk:

4. Live Interactive Upload Studio

Test drag-and-drop uploads, inspect CDN response URLs, and preview image thumbnails directly inside the docs:

👉 https://playground.nileslabs.com/docs/uploads

Conclusion

Say goodbye to dummy file upload mocks. Test real FormData requests, simulated bandwidth, and CDN responses with Playground API today!