Sending large files: P2P, cloud link or email?
Published
A photo album, a video clip or a project folder rarely fits in an email. People then choose between a cloud link, a direct transfer and tricks such as splitting the file. Each option has a different effect on speed, cost, convenience and privacy. This article compares the three main methods, gives the limits that the providers themselves publish, and offers a simple way to decide.
Option 1: email attachments
An attachment is the easiest method, because the recipient already has an inbox and needs no new account. The catch is the size limit. For personal Gmail accounts Google's help page states a limit of 25 MB; for work and school accounts the administrator sets the limits. When you attach something larger, Gmail removes the attachment and puts a Google Drive link in the message instead, so the recipient receives a link, not a file. Other providers differ and change their limits over time, and Microsoft's own pages show different figures for different kinds of account, so check the current help page of the service you use. Apple's Mail Drop works the same way: at the time of writing, its help page describes attachments up to 5 GB that are kept for a limited period, then removed.
Email has other drawbacks. The message is copied into several mailboxes and backups and stays there for years. The recipient's service may enforce a smaller limit than yours and reject the message. Attachments also grow when they are encoded for transport, so a file close to the limit may fail. Email is a fine choice for small documents that you are happy to leave in an archive, and a poor choice for sensitive or very large files.
Option 2: cloud storage links
A cloud link means you upload the file to a storage service and send the address of the upload. The size limits are much larger than for email and the recipient can download at any time, even if they were offline when you sent the link. Some services keep a link alive for a limited time or let you set a password or an expiry date. The main costs are time and trust.
- You must upload first, then the recipient downloads. The file crosses the internet twice, and your upload speed is often the slowest part.
- The provider stores a copy on its servers and can usually read it unless you encrypt it yourself before uploading. Treat it like any other file on someone else's computer.
- Sharing settings are easy to get wrong. A link that works for anyone who has it can be forwarded, indexed by mistake or opened by a search tool. Choose the narrowest option, such as specific people, and set an expiry.
- Storage can fill up. Free accounts are limited, and a shared file may count against your quota.
- You must delete the file or the link afterwards, or it stays online.
Cloud links are the best choice when the recipient may not be online, when many people need the same file or when the file is very large and must stay available for a while.
Option 3: direct peer-to-peer transfer
In a peer-to-peer (P2P) transfer, your browser sends the file straight to the recipient's browser, using the same WebRTC technology as video calls. There is no upload to a storage service, so no copy is left on a server and no account is needed. Because the file only crosses the internet once, the transfer can be as quick as the slower of the two connections.
- Both people usually have to be online at the same time, and the connection has to be established. If one side closes the tab, the transfer stops.
- Networks can prevent the direct path. Strict firewalls, some VPNs and school or office networks often block it. The article about video calls on work and school networks explains why, and the WebRTC connectivity test on this site shows whether your network allows it.
- Services differ in limits. ChatLite, for example, accepts files up to 100 MB. It sends them directly when the connection works, waits up to 15 seconds for the direct connection to come up, and falls back to its server only for files up to 8 MB. Larger files need the direct connection, and if the other person is offline the file waits in a short-lived queue.
- Browser tabs hold the file in memory while it is transferred, so very large files can fail on weak devices.
- Direct connections are encrypted between the browsers; if a transfer goes through a server instead, it is encrypted on the road but not end to end. See the article on end-to-end encryption.
P2P is the best choice for a one-time handover between two people who are available now, for files you do not want to leave on anyone's server, and for moderate sizes.
Comparison at a glance
- Speed: P2P is usually fastest for two online people. Cloud links need an upload and a download. Email is quick only for small files.
- Size: cloud links allow the largest files. Email is the most restricted. P2P depends on the service and the devices.
- Convenience for the recipient: email and cloud links work whenever they open them. P2P needs them to be present.
- Privacy: P2P leaves no copy on a server. Cloud links and email leave copies with the provider.
- Reliability: email and cloud links are very reliable. P2P depends on both networks.
- Cost: P2P is free of storage costs. Cloud storage may need a paid plan for large amounts.
A simple way to decide
- Is the file small, such as a document or a few photos, and not sensitive? Attach it to an email.
- Is the file large, or does it need to stay available, or are many people involved? Use a cloud link with limited access and an expiry date.
- Is the file for one person who is online now, and would you prefer that no copy stays on a server? Try a direct transfer, and keep a cloud link as a backup if the connection fails.
- Is the file sensitive? Prefer a method where you control the key: encrypt it yourself first, or use a direct transfer, and check what the service stores.
Tips that help with any method
- Compress folders into a single archive, and use a lossless format for documents.
- Reduce the size where quality allows it, for example by exporting a video at a lower resolution.
- Check the file name and contents before sending. Metadata inside photos and documents can include locations and authors.
- Tell the recipient what is coming and ask them to confirm receipt.
- Delete the files and links when the job is done.
- On a shared or public computer, clear the downloads and browser data afterwards.
About ChatLite
ChatLite sends files directly between browsers when it can and gives the limits above in its file transfer guide, so you know in advance what it can and cannot send.
References
Official documentation used to check this article. Pages are maintained by their owners and may change.
Reviewed against ChatLite's current behavior on .