threema-web is the browser client for the Threema messenger, mirroring your encrypted chats, contacts, and media onto a desktop computer. You pair it by scanning a QR code with the Threema app on your phone, which stays online as the relay for every message.
threema-web is the browser-based desktop client for Threema, and it puts your full message history, contact list, and shared media into a normal browser tab instead of a separate application. Getting started takes seconds: open the page, let it display a QR code, then scan that code from the Desktop/Web section of the Threema app on your phone. From that point the two devices are linked and every conversation is available on the larger screen, with text, photos, files, emoji, and reactions arriving in real time. Nothing is installed and nothing stays behind afterwards, because the browser throws the synchronized data away the moment the session ends.
The pairing model explains most of the trade offs. Because your phone remains the source of truth and relays traffic, the browser holds no independent copy of your account keys, and the connection is encrypted end to end between the two devices. That design also means the phone has to stay online while you type, and closing the tab or letting the session time out ends the link until you scan again, unless a session password was set in advance. Anyone weighing self hosted or serverless alternatives such as Element will notice the contrast: this client depends on the phone, but it keeps the vendor out of the message path.
The reason to use threema-web is convenience without a second installation or a second identity. Your chats, including the history you already have, appear in the browser with no migration and no re-inviting contacts, so the desktop becomes an extension of the account rather than a parallel inbox you have to maintain. Files can be dragged straight into a conversation, animated GIFs play inline, emoji reactions add a quick acknowledgment, and groups and distribution lists can be managed from the keyboard instead of a thumb. Nothing is written to persistent storage on the computer: end the session and the synchronized messages are deleted, which matters on borrowed or shared machines. Because the pairing channel is end to end encrypted, the message content never becomes readable to a relay server, and Threema's broader design avoids collecting address books and usage metadata. The client is also open source and can be hosted on your own server, so a cautious organization can serve the interface internally while still relying on the phone for keys.
Key capabilities and highlights.
The link between phone and browser is established by scanning a QR code that threema-web displays, using the Desktop/Web section of the Threema app. No password reset, sync token, or email confirmation is involved, and the pairing can be protected with a session password so you do not have to repeat the scan every time you reopen the page.
Every conversation, contact, and media file stored in the mobile app is available on the desktop through threema-web, including history from before the session started. Scrolling back through old threads, opening a photo someone sent last month, or checking a document received in a group works much as it does on the phone, just with a larger screen and a real keyboard.
Send and receive text messages, pictures, videos, and arbitrary documents from the browser, dragging files directly from the desktop into a conversation to attach them. Emoji, animated GIF playback, and emoji reactions round out the everyday messaging experience, so routine replies and quick approvals do not force a trip back to the phone.
Create and manage groups and distribution lists from the desktop instead of tapping through a phone interface. Adding a member, renaming a group, or broadcasting to a saved list can be done while you are already working at the computer, which is faster and less error-prone when coordinating a team across several active conversations at once.
All traffic between the mobile app and the browser is end-to-end encrypted, with the phone acting as the relay rather than a vendor server holding your messages. Content passing through any intermediate connection stays unreadable, and because nothing is persisted in the browser, closing the session leaves no message history on the computer.
Each desktop session can be watched and terminated from the phone, and synchronized content disappears from the browser as soon as the session ends. A session password option keeps the pairing alive across browser restarts for convenience, while inactivity timeouts limit how long a forgotten tab stays connected to an unattended workstation.
The web client is open source and can be served from your own infrastructure, so an organization can control where the interface code comes from instead of trusting a public site to deliver it. That also lets auditors review the client, which matters when messaging is subject to internal security requirements or regulatory scrutiny.
threema-web deliberately leaves calls, voice notes from the desktop, and several mobile-only conveniences to the phone app, and it needs the phone to stay online while you chat. Anyone who wants phone-independent desktop messaging should look at the dedicated desktop application, which shares the same design but keeps working even when the phone is switched off.
Browse historical releases and previous builds.
No old versions have been added yet.
Common questions about threema-web.
It is the browser client for the Threema encrypted messenger. It opens in a desktop browser, displays a QR code, and after you scan that code with the Threema app on your phone, it shows all of your chats, contacts, and media. Nothing is installed, and the browser keeps no copy of the messages once the session ends.
Yes. threema-web is a companion client rather than a standalone account, so the mobile app must exist and stay connected to the internet while you use the browser. If the phone goes offline or the session times out, the desktop view stops working until you pair the two devices again.
Not after the session ends. Messages are synchronized to the browser while the pairing is active and deleted as soon as the session is terminated, which is why the client suits shared or borrowed computers. The authoritative copy of your message history remains on the phone.
Yes. Communication between the threema-web client and the mobile app is end-to-end encrypted, and any relay involved in establishing the connection cannot read message content. Message encryption itself relies on Threema's end-to-end scheme, under which the server discards a message once it has been delivered.
You get full access to contacts, chats, and media, including past conversations, plus sending and receiving text, pictures, files, and emoji, animated GIF playback, emoji reactions, and management of groups and distribution lists. You can also add contacts and set a session password. Voice and video calls are handled by the mobile app rather than the browser client.
Yes. Threema offers a dedicated desktop application built on the same architecture that can keep working when your phone is switched off or offline, which removes the repeated QR scans and session timeouts that come with browser use. The feature set is otherwise closely aligned with threema-web.
Yes. The client source is open, and the project documents hosting it on your own web server, which lets an organization control delivery of the interface code. Keep in mind that self-hosting changes where the page is served from, not the underlying requirement that the paired mobile app holds the account keys.
threema-web is the browser client for the Threema messenger, mirroring your encrypted chats, contacts, and media onto a desktop computer. You pair it by scanning a QR code with the Threema app on your phone, which stays online as the relay for every message.
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