Product data sheet
An email client that runs entirely on your device.
liber connects to the accounts you already have over IMAP, SMTP and POP3. Mail is stored, indexed and searched on the device. No liber server holds any of it.
General description
liber is a mail client, not a mail service. It hosts no mailboxes and issues no accounts. You connect it to the provider you already use.
Everything the client does happens on the device, including the mail protocols, storage, indexing and search. There is no liber server that receives, stores or processes email.
No telemetry, no tracking, no ads, no nonsense. Just email.
Operating principle
The engine is a complete IMAP, SMTP and POP3 implementation compiled to WebAssembly. It runs inside the browser's wasm sandbox, the same isolation the browser puts around an unknown website. TLS to your mail provider begins inside that sandbox, so the stream is ciphertext before anything else on the machine can see it.
The sandbox cannot open a raw network socket, so the ciphertext leaves through a relay. On the web that is a thin forwarding service on the origin that served the client. The desktop and mobile apps have the relay built in. Either way it forwards bytes it cannot read and keeps nothing.
TLS begins inside the engine's sandbox and runs unbroken to the mail provider. Nothing on the path holds a key.
Transport behavior can be verified with a packet capture against any build of the client.
Security properties
| Mail storage | Encrypted at rest on every platform. |
|---|---|
| Credentials | Sealed on the device. Never stored in the clear. |
| Transport | TLS from the engine's sandbox to the mail provider. |
| OpenPGP | Built in. Keys are generated or imported on the device, and mail can be signed and encrypted per message. Encrypted mail stays ciphertext at the provider. |
| Our copy of your mail | None. We run no mail store and no database. |
| Account requirements | None. The one optional account is a liber sync vault, and it holds only sealed data. |
| Analytics | None. No tracking and no advertising. The client sends a service check-in with its version and account count. Never content, credentials or server names. |
Interoperability
| Protocols | IMAP · SMTP · POP3 |
|---|---|
| Providers | Gmail, Google Workspace, Microsoft 365, Fastmail, Zoho and any other server with IMAP, SMTP or POP3 access. |
| Accounts | Several at once, with a unified inbox across them. |
| Mailbox | Conversation threads, folders, labels, filters and flags. |
| Search | Full text, indexed on the device. |
| Contacts | A built in address book. It can connect to your provider's address book over CardDAV. |
General arrangement
Folders on the left, the message list in the middle, the conversation beside it. Web and desktop share the layout. Narrow screens get a compact form.
General arrangement of the client as it ships on desktop and the web.
Sync
liber sync copies your accounts, passwords, settings, rules and keys to all your devices. You approve a new device from one you already have. The service stores only ciphertext it cannot read, and mail never moves through it.
Sync is off until you turn it on, and the client is complete without it. The data sheet has the details. Organizations provision it centrally under the organization plans.
Availability
| Web | mail.liber.sh. The full client in the browser. Nothing to install. |
|---|---|
| Desktop | Installers for Windows, macOS and Linux, plus the common package managers. See ordering information. |
| Mobile | Android, installed directly from the release archive. |
| Editor | An extension for Visual Studio Code, with mail on the activity bar. |
Plans and pricing
| Plan | Description | Price |
|---|---|---|
| liber | The client, on every platform. | Free |
| liber sync | Your setup on every device, hosted by liber.sh. | USD 2.99 / month |
| liber professional | Sync for organizations, hosted by liber.sh. | USD 48 / seat / year |
| liber enterprise | The full deployment on your own infrastructure. | By arrangement |
See the price schedule and the organization brief.
The web app is the full client. Installers for every platform are on the releases page.