What Is File Transfer and How Do You Send Large Files Online?
File transfer online means moving a file from your device to a service that stores it and then hands it to a recipient — usually by email link or a shareable URL. You need a dedicated transfer service rather than a plain email attachment once files get into the multi-gigabyte range, because most email providers cap attachments far below that. On SendBig, for example, the stated free limit is up to 30GB per transfer, and the site describes resumable uploads for logged-in users, so a dropped connection doesn't force you to start over.
The basic send flow
The steps below follow the upload card described on SendBig. Other services use similar wording, so the sequence transfers.
- Choose or drop your files. Select a file, or drag files and folders onto the drop area. The page shows a running total (the example on the site reads "5.00GB Total"), so you can see when you're approaching the limit.
- Add the recipient. Enter your own email in the "Your email" field and the recipient's address in the "Email to" field. You can add more than one address.
- Add a message (optional). The "Email message" field carries a note alongside the download link.
- Set protection and expiry (optional). You can password-protect the transfer, choose an expiry date, and cap the number of downloads.
- Upload. Start the transfer and wait for it to finish. The recipient gets a link; you can also copy a shareable link and post it yourself.
- Confirm delivery. Ask the recipient to open the link before the expiry date. Files are automatically deleted from the servers once the transfer expires.
Expected result: the recipient opens a link, optionally enters the password you gave them separately, and downloads the file.
Why large files need a transfer service
Email attachments are the wrong tool past a certain size — the message bounces or the provider silently strips the attachment. A transfer service solves this by uploading the file once to a server and sending a link instead of the file itself. That also means:
- The recipient doesn't need an account to download, in most setups.
- You can send to many people with one upload.
- You control how long the link lives and who can open it.
Resumable uploads: what to do when your connection drops
This is the single most useful feature for multi-GB files. SendBig describes resumable uploads for logged-in users: you can start an upload today, shut down your computer, and resume it tomorrow from where it stopped.
How it works in practice, per the site's description:
- Log in before uploading. Incomplete uploads are retrieved and shown first inside the upload card the next time you visit while logged in.
- For each incomplete upload, select the same file on your computer and click resume. The upload continues from the last completed point rather than from zero.
Common trap: if you rename, move, or re-export the file between sessions, the service may not match it to the incomplete upload. Keep the file where it was.
Security choices worth making
SendBig states that files are encrypted in transit and at rest using AES-256, that SSL/TLS protects data transfer, and that its servers are ISO 27001 certified. It also states that files are automatically deleted once the transfer expires. On top of those defaults, you can add:
| Control | What it does | When to use it |
|---|---|---|
| Password protection | Adds end-to-end encryption; only you know the password | Anything sensitive — send the password through a separate channel |
| Expiry date | Deletes files from the server after a set time | Anything you don't want lingering |
| Download limit | Caps how many times the transfer can be downloaded | Confidential documents, one-recipient sends |
Common failure points and fixes
- File too large. Check the total against the service's limit before uploading. Split large video exports or use a higher tier if you need more.
- Expired link. The recipient waited too long. Re-upload and send a fresh link, or set a longer expiry next time.
- Wrong recipient address. A typo sends the link to a stranger. Double-check the "Email to" field before uploading, and use a download limit as a backstop.
- Upload interrupted mid-transfer. Log in and resume rather than restarting. If you weren't logged in, you may have to begin again.
- Recipient can't open the file. Usually a password mismatch or an expired link — confirm both before troubleshooting anything else.
Picking between services
Compare on the dimensions that actually affect your send: maximum free file size, whether resumable upload is available on the free tier, encryption defaults, expiry and download-limit controls, and whether the recipient needs an account. SendBig's stated position is a 30GB free limit with resumable uploads for logged-in users and AES-256 encryption; check the current terms on any service before relying on a specific number, since limits and plan details change.