Penumbra is a simple, secure, and private note-taking app. It runs entirely in your browser, and your notes are never sent to a server. You can even use it offline.
Encrypt them with a password, and keep them safe on your device.
No servers, no third parties, no subscriptions.
Penumbra uses the Web Crypto API to securely encrypt your notes with a 256 bit AES key derived from your password.
Penumbra runs entirely in your browser - you can even use it offline. There is no server, and nothing leaves your device.
Penumbra is a progressive web app, which means you can install it on your device and use it like a standalone app.
Penumbra uses Slate.js to provide a rich text editor with support for headings, formatting, and more.
In addition to its own encrypted format, Penumbra can export your notes to Markdown, so you can use them in other apps.
Penumbra is entirely open source. You can view the source code on GitHub, and even contribute to the project if you like.
If you have anything else you want to ask, check out the GitHub repo.
The menu in the top-right corner has options to open and save notes. You can save with any file extension you like - the app will know if it's a Penumbra note or not.
The notes never leave your device and they are encrypted with the strongest encryption available. Remember that even the strongest encryption is useless if you can be compelled to give up your password however.
There is no way to recover a lost password. You will have to delete that particular note and start again. Password managers are a good way to avoid this problem.
In addition to saving (which keeps the same password) you can 'save as' which treats your note as though it's being saved for the first time, and will prompt for a password.
In the URL bar of your browser, there will be a button you can click to download the app locally. This will give you an icon in your app drawer and allow you to use Penumbra without opening a browser window.
In the settings, accessed from the menu in the top right, you can adjust the theme, font, and other settings. You can also make these settings document-specific.
Penumbra is currently entirely free. In the future, there may be a paid version with additional features, but there are no immediate plans for this.
Penumbra has an AGPL license, which means you can use it for free for anything, host your own version, or build on it in another non-profit, open app. You may not charge for any tool built from Penumbra however.
You can raise an issue on GitHub, or contact me on Twitter - samirelanduk in both cases. Note that I may not be able to respond immediately to all requests.