Big Tech wants to lock your productivity into their AI platforms and mine your data. I'm building the alternative. Onyx: encrypted notes, Nostr sync, open source, AI skills library. Your data stays yours.

Building Onyx: Why I'm Creating an Open Source Alternative to Big Tech's AI Productivity Tools

Hello all!

I started a new career path at the beginning of this year and immediately felt the need for an AI-powered productivity tool to help manage my daily workflow—an executive assistant of sorts for task management, scheduling and meeting reminders, content writing and social management, general prioritization, and project management.

I had recently started using Obsidian to organize all my notes, so my initial thought was to throw Claude Code at my Obsidian vault and see what would happen. The results were amazing, but I knew I could do better. I started creating skill after skill, refining my workflow with each iteration. I integrated open source tools like Taskwarrior, Khal, and Khard. I pulled down all of my tasks, issues, and merge requests from GitHub and GitLab. The system was becoming genuinely powerful.

Then, in the first week of January, I discovered OpenCode and everything changed.

I decided to build an OpenCode plugin for Obsidian. Being able to accomplish all of this without switching between applications was incredibly productive and powerful. I showed it to a few friends and they were floored. We discussed it at length, and that's when I had my realization: this was the future. This was AI for non-technical people. My friends don't code, but they could all benefit from personal assistants and productivity suites.

But I had doubts. My very technical, command-line-based, Obsidian-centric approach wasn't going to work for most people. And as I dug deeper, I realized I wanted to be truly open source—and Obsidian isn't. I wanted a polished interface for syncing. I wanted a free (or at least cost-effective) and simple method for synchronization that non-technical users could actually set up and use.

I started working on a solution. Then, two days later, Anthropic announced Claude Cowork.

And that's when it truly hit me.

This was the billion-dollar idea—and every major tech company would be racing to implement their own version. They would mine user data and lock users into their platforms. This would be terrible for user choice and freedom. We needed an open source alternative, and we needed it fast.

(And then I had to disappear for a week due to work commitments, but my team did win $25K in an AI Hackathon, so it's not all bad.)

Now that I'm done with the backstory, let's get to the app.

Introducing Onyx

Onyx is a private, encrypted note-taking app with Nostr sync.

Onyx lets you write markdown notes locally and sync them securely across devices using the Nostr protocol. Your notes are encrypted with your Nostr keys before being published to relays, ensuring only you can read them.

This is the foundation of what I'm building—a truly open, user-controlled productivity platform where your data belongs to you and syncs through decentralized infrastructure rather than corporate servers.

GitHub Repository: <https://github.com/derekross/onyx>

Features

Core

Markdown Editor — Write notes with full markdown support and live preview
Local-First — Your notes are stored locally as plain markdown files and work offline
Nostr Sync — Encrypted sync across devices via Nostr relays
Secure Storage — Private keys stored in your OS keyring (Keychain, libsecret, Credential Manager)
Cross-Platform — Linux, macOS, and Windows

Document Sharing

Share with Nostr Users — Send encrypted documents to any Nostr user via npub, NIP-05, or hex pubkey
Notifications Panel — See documents shared with you, with sender profiles and timestamps
Import Shared Docs — Import received documents directly into your vault
Revoke Shares — Remove shared documents you've sent to others

Publishing

Publish as Articles — Post markdown notes as NIP-23 long-form articles
Draft Support — Publish as drafts (kind 30024) or published articles (kind 30023)
Auto-generated Tags — Suggests hashtags based on document content

Privacy & Security

End-to-End Encryption — All synced content encrypted with NIP-44
Block Users — Block bad actors using NIP-51 mute lists
Secure Previews — XSS protection and URL sanitization for shared content
Private Mute Lists — Blocked users stored encrypted so only you can see them

File Management

File Info Dialog — View local file details and Nostr sync status
NIP-19 Addresses — See naddr identifiers for synced files
Sharing Status — See who you've shared each file with

AI Skills Integration

Integrated Skills Library — Browse and install AI skills directly from skills.sh, a curated library of productivity-enhancing capabilities
One-Click Installation — Add new skills to your workflow without any technical setup or configuration
Easy Management — Enable, disable, and update skills from within the app
Community-Driven — Access skills created by the community, from document creation to task automation to specialized workflows
Extensible — Build and share your own skills to help others boost their productivity

How Sync Works

Onyx uses custom Nostr event kinds for encrypted file sync:

Kind	Purpose	Encryption
30800	File content	NIP-44 (self)
30801	Vault index	NIP-44 (self)
30802	Shared documents	NIP-44 (recipient)
30023	Published articles	None (public)
30024	Draft articles	None (public)
10000	Mute list	NIP-44 (self, optional)

All synced content is encrypted using NIP-44 with a conversation key derived from your own public/private key pair. This means only you can decrypt your notes—relays only see encrypted blobs.

Shared documents are encrypted to the recipient's public key, so only they can decrypt them.

Tech Stack

Tauri 2.0 — Rust-based desktop framework
SolidJS — Reactive UI framework
CodeMirror 6 — Text editor
nostr-tools — Nostr protocol library

Installation

Pre-built binaries are available for Linux, macOS, and Windows on the Releases page.

For macOS users: The app isn't currently signed with an Apple Developer certificate. To install, open Terminal and run:

xattr -cr /Applications/Onyx.app

What's Next

This is just the beginning. Onyx represents the foundation of an open source, privacy-first productivity suite that puts users in control of their data. The goal is to prove that we don't need to sacrifice our privacy and freedom to benefit from AI-powered tools.

If you're interested in contributing or following along, check out the repository and give it a star. Let's build the future of open productivity tools together.

License: MIT