Allowlisting Bytescale for Corporate Networks
If uploads work on personal devices or home networks but fail on work computers, the most likely cause is a corporate firewall, proxy, VPN, browser policy, or endpoint security tool blocking one of the required Bytescale requests.
We strive to ensure Bytescale is correctly categorized and remains allowlisted across major corporate proxies and security platforms — if you experience an issue that appears to be caused by corporate proxy rules or network filtering, please contact Bytescale Support with details about the corporate proxy or firewall you use, and we will do our best to help resolve it where possible.
Domains to Allowlist
Ask your IT team to allow outbound HTTPS traffic on port 443 to the following domains:
| Domain | Purpose |
|---|---|
https://api.bytescale.com |
Bytescale API requests, including upload setup and completion requests |
https://upload-prod-files.s3.dualstack.us-east-1.amazonaws.com |
Pre-signed upload URLs used for browser/client-side file uploads |
https://upcdn.io |
Bytescale CDN file delivery, previews, downloads, and transformations |
https://js.bytescale.com |
Bytescale SDK or Upload Widget script files, if loaded via a script tag |
If your application uses a custom CDN domain or custom CNAME for file delivery, allowlist that domain as well.
Required HTTP Methods
For uploads to work correctly, the network must allow:
| Method | Used For |
|---|---|
POST |
Creating or starting uploads via the Bytescale API |
PUT |
Uploading file bytes to pre-signed upload URLs |
GET |
Loading delivered files, previews, SDK scripts, widgets, or upload-related metadata |
Common Symptoms
This issue often appears as one of the following browser errors:
Failed to fetchFailure to fetchNetworkError- A request that appears as
(blocked)or(failed)in browser DevTools - Uploads working on personal devices but failing only on company-managed computers
- Uploads working on a mobile hotspot but failing on the corporate network
Recommended Checks
If allowlisting the domains above does not resolve the issue, collect the following from an affected work computer:
- Open the browser's Developer Tools.
- Go to the Network tab.
- Retry the upload.
- Find the failed request.
- Capture the request URL, HTTP method, status/error, and any visible console error.
- Ask your IT team which corporate firewall, anti-malware browser extension, and/or VPN your workstation uses.
Please share this information with Bytescale Support or your vendor.