How to Test File Uploads: Practical Checklist
A practical guide to file upload testing, including formats, size limits, errors, progress indicators and security checks.
Start with successful uploads
Upload a supported format below the size limit. Verify the file name, MIME type, extension, size and server response. Download the uploaded result and compare its contents with the original.
Test boundaries and failures
Try files just below, at and above your application's configured upload limit. Check empty files, unsupported extensions, duplicate names, canceled requests, interrupted connections and slow uploads. Make sure error messages explain what happened.
Check security and accessibility
Validate file types on the server rather than trusting the browser extension. Limit upload size and access permissions. Test keyboard navigation, accessible labels and clear progress announcements. Never run unknown uploaded content directly on your server.
Repeat across sizes
Use 1 MB and 2 MB files for fast checks, 5 MB and 10 MB for common workflows, and 20 MB and 50 MB for stress and timeout scenarios. These sizes are useful benchmarks, not substitutes for realistic content validation.
Download sample files by format
Browse available test files in six sizes from 1 to 50 MB.