What Is Wormhole? How This Browser File Sender Works

What is Wormhole, in short?

Wormhole is a website for sending files to another person through a link. You open the page, pick or drag in the files you want to share, and the site gives you an address to pass on. There is no account to create, which makes a wormhole link about as simple as file sharing gets. The official page describes it as simple, private file sharing, with end-to-end encryption and a link that expires on its own.

The home page invites you to send up to 10 GB, and it is built around one idea: the people running the service should not be able to read what you send. Files are not kept forever either. According to the vendor's description, they vanish after download or after 24 hours, so a transfer leaves nothing lying around on a shared drive or in someone's inbox.

It runs in an ordinary browser, so it works the same from a phone as from a laptop. That also makes it a handy fit for the Utilities group of web apps, which collects small single-purpose tools like this. If you want a deeper look at the app itself, the Wormhole page in the directory gathers the essentials in one place.

How does a Wormhole transfer work step by step?

Start by opening the site in any browser and choosing the files, either with the select button or by dragging them onto the page. Your browser then encrypts the file locally, before anything leaves your machine. Once that is done you get a link. The decryption key is part of that link, in the portion after the # symbol, known as the fragment, and browsers do not send the fragment to the server.

Send the link to your recipient through a channel you trust, such as a private message. When they open it, their browser uses the key in the fragment to decrypt the file. The service in the middle only ever handles an encrypted blob it cannot open, which is a property of how the link is built rather than a promise written in a privacy policy.

For files under about 5 GB, the transfer can happen peer-to-peer while both tabs are open, which means the file never touches a server at all. The upper limit is 10 GB. Keep your tab open until the recipient has finished, because closing it too early can make the transfer fall back to the server copy or fail.

Is Wormhole encrypted? What the official page says

The Wormhole home page states that it lets you share files with end-to-end encryption and a link that automatically expires. Those are the two claims the vendor makes up front, and they are worth separating. Encryption protects the contents from anyone who handles the file in transit or in storage. Expiry limits how long the file exists at all, so your files do not stay online forever.

The site also links to a security page, a FAQ and a note on why it was built, which are the places to read if you need more detail than the home page gives. The vendor's description adds that there is no account and no tracking. This article does not go beyond what the site itself says about encryption, so for sensitive material such as medical scans, read those pages first.

One practical consequence of the design is that the link itself is the key. Anyone who obtains the full link, fragment included, can download the file while it is still available. Treat it like a password: send it privately, and avoid pasting it into a public thread or a group chat that includes people who should not have the file.

What can't Wormhole do? Size, retention and accounts

On size, the official page says you can send up to 10 GB. That is the figure to plan around, and it is a ceiling set by the service. In practice the device doing the sending matters too. Because encryption happens in the browser, very large files are bounded by the memory of the sender's device, so an old phone will struggle where a laptop will not.

On retention, files disappear after download or after 24 hours. On the free tier that expiry is not adjustable, which makes Wormhole the wrong choice for anything you need to keep available, such as a download that several people will fetch over a few days. If you need a permanent home for a file, use storage designed for that and treat Wormhole as the delivery step.

On accounts, there is nothing to sign up for, either for you or for the recipient, and the vendor says it does not track you. That does not make the link private by itself, because the service cannot tell who is holding it. Peer-to-peer mode also needs both tabs open at once, so it suits a live handover better than leaving a file for someone to pick up later.

When should you use Wormhole instead of email?

Reach for it when the file is large or sensitive. Typical cases are a video edit going to a client who should not have to make a Dropbox account, a database dump or design archive moving between two machines that share no cloud, or a contract, medical scans or press embargo going to someone outside your organisation. In each case the point is that no intermediary needs to be able to read the file.

It is also the least awkward way to get a large file off a phone: open the site, pick the file, send the link. Unlike an attachment that stays in an inbox until someone deletes it, a Wormhole transfer expires on its own, so nothing accumulates. The trade-off is that the recipient must download within the window, so tell them a file is coming.

If the other device is on the same Wi-Fi network, ShareDrop is a different option: its own page describes peer-to-peer WebRTC transfer between devices, with no upload to a server. This guide to a free AirDrop alternative for Android and Windows covers it in more detail. For sending to someone elsewhere, see the Wormhole listing and the official site it points to.

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