Client-server transfer
Upload once, share a link, and let the recipient download whenever they're ready - even after you close the tab. Every file is encrypted on your device before it leaves it.
In client-server mode - the classic way most transfer tools work - your files are uploaded to Transferify's storage first, then handed to the recipient through a download link. Because the file lives on our servers, the transfer is asynchronous: you and the recipient never have to be online at the same time.
That's the key difference from a live peer-to-peer transfer. Hosted links cost you an upload wait up front, but once it's done the link keeps working on its own - the recipient can grab the file minutes or days later, from any device, long after your tab is closed.
How a hosted transfer works
- Your files are encrypted on your device with AES-256-GCM before a single byte leaves it - the server only ever sees ciphertext.
- The encrypted data is split into ~8 MiB chunks and sent straight to storage as an S3 multipart upload, so a large file goes up as many independent parts instead of one fragile stream.
- Any part that fails is retried automatically with exponential backoff, and its upload URL is re-signed on every attempt - so a brief network drop doesn't cost you the whole upload.
- Once the upload finishes, your share link goes live. The recipient opens it and the file streams down in ~8 MiB windows, decrypted on the fly in their browser - no account, nothing to install.
Built for big files and shaky networks
Holding the file server-side is what makes this mode dependable:
- Chunked, multipart upload - A large file is sliced into ~8 MiB parts and uploaded independently, so throughput stays high and a single dropped part never restarts the whole transfer.
- Automatic retries - Each part gets up to three attempts with exponential backoff and a freshly signed URL, so a multi-hour upload over unreliable Wi-Fi still finishes.
- Large files - Send up to 3 GB free, 50 GB on Plus and unlimited on Premium - the multipart engine carries the size.
- Streamed, memory-safe downloads - The recipient's browser pulls the file in ~8 MiB windows and writes it straight to disk, so even huge files never have to fit in memory - and the download can be re-run any time before the link expires.
Still end-to-end encrypted
Hosted doesn't mean exposed. Your files are encrypted on your device with AES-256-GCM before they're uploaded and stay encrypted at rest - Transferify's servers only ever handle ciphertext, never your plaintext. Each ~8 MiB chunk is sealed separately, so the download fails hard if a single byte is tampered with.
By default we escrow the encryption key, wrapped in AWS KMS, so a lost link is still recoverable; switch on Zero-Knowledge mode and the key never reaches us at all. See how zero-knowledge encryption works.
Client-server vs peer-to-peer
Two ways to send the same file. Client-server stores it so it can wait; peer-to-peer streams it live, device to device, and stores nothing.
| Aspect | Client-server | Peer-to-peer |
|---|---|---|
| When the link works | As soon as the upload finishes | Instantly, before any upload |
| Path the file takes | Device → server → device | Device → device, directly |
| Recipient | Downloads anytime, even days later | Must be online while you send |
| When you close your tab | Link stays online | Transfer ends |
| Where the file lives | Encrypted on our servers until it expires | Nowhere - never stored |
| File size | 3 GB free · 50 GB Plus · ∞ Premium | Unlimited |
Which should you use?
Choose client-server when the recipient may be offline, when you want the link to keep working after you close your tab, or when you need passwords, expiry dates and download limits on the file.
Choose peer-to-peer when you're both online and want the file to stream instantly, at full speed, with nothing ever stored on a server.