Variorum

Variorum was built by one person and thousands of AI agents over the course of four months. I’m Lillian, the human behind this project. I want to take the chance to introduce myself and share a bit about the app, technology, and what it all means to me.

I created Variorum because I’m a software developer, I love writing, and I wanted to build my own perfect writing app. It was only once the whole picture came together that I realized the app philosophy I had designed for my own writing enabled a new way of working with AI.

Let me be clear: providing a new surface for AI to write for you is not the purpose of this app. I do all of my own writing because writing is an invaluable way to refine and develop my thoughts, to push them further than they can go in the limited context window of my own mind. I also enjoy it. Every word you read here was typed by human fingers and I had an AI read over my draft and leave comments. I used an “and” instead of a “but” because I believe that collaboration instead of replacement is not only possible but tragically underserved by current structures and workflows.

Software itself can and should provide features that increase the capacity of people to control how they work with AI. Variorum carves out territory in the no man’s land between “used AI for this” and “didn’t use AI for this”, binary labels that unhelpfully collapse a spectrum of different uses. There are real differences between having an AI leave comments on your original writing, edit it directly, draft text for you to edit, and pull together sources for you. Variorum lets you set your own boundaries with tools instead of writing prompts requesting that they be honored.

There are three key features in Variorum, each built first for my own writing, that together make working with AI more like spinning a dial than flipping a switch. Each addresses a core challenge that the AI world’s ubiquitous default — a folder of markdown files — struggles with: managing what AI can change, reviewing those changes, and controlling what it can see.

The namesake feature of this app is the ability to make different versions of a paragraph — a variorum is defined as a scholarly edition of a text that compiles variant readings. Where most writing apps resemble an improved typewriter, Variorum allows for a new way of organizing information by giving each text block a durable identity. The smooth viewing, editing, and switching between versions of a block (“takes”) seemed obviously useful for drafting, but I soon found it was a more fundamental abstraction. Use takes to make a bilingual book, an architecture document enriched with code snippets, and whatever else you can dream up. Takes allow for fine-tuned control of what an AI can change by enabling a “write new” tier of AI permissions. They maintain a structural moat between you and the AI — its words are not above and below yours, but beside them, intrinsically linked without bloating your document. Sometimes the worst part of working with AI is being drowned out by an ocean of words that are in English, but only technically. Variorum allows lengthy AI comments on a design document to be tucked away and revealed at will.

Version control, purpose-built for writing, is the second guardrail. I took some of the best parts of git, like commits and traceable lineage, and used block identity to sidestep the line-based diffs that make git itself unsuitable for my work. The result is an app where each version of each paragraph has its own complete history, saving a version preserves the full note, and it is easy to compare a particular paragraph to what it used to be. The ease of seeing what changed in the compare view makes it like reviewing a pull request of prose. Variorum automatically commits before and after any AI changes on every take, allowing for easy reversion. My favorite feature is that ⌥⌘Z can always undo the latest AI change.

The final ingredient of the defining trinity is privacy. Each Variorum library is encrypted locally and you can choose between Standard and Castle mode. Standard mode exists because I wanted to be able to give this app to my mom without making it feel like opening a crypto wallet every time — it stores convenience copies of your library key, so Variorum opens on your unlocked Mac. Castle mode exists because I’m disturbed by the fact that simply flying to another country gives the government where I live the right to search all of my personal devices, including forcing the use of biometrics. In Castle, Variorum doesn’t open even on an unlocked Mac without your passphrase or twelve words, with Touch ID optional. Conveniently, being stored in ciphertext on disk prevents a rogue AI with filesystem access from reading your work, unlike a folder of unencrypted markdown files.

Variorum is also built with the principle that AI should always be opt-in, rather than opt-out. I hope that even those who don’t want to use AI at all reach for Variorum for its capabilities as a writing editor, with full confidence that their work is private not because of terms and conditions but because of keys and encryptions. For those who do connect an MCP client, it makes every access grant visual, clear, and easy to revoke. Unlike the obfuscated reality of the command line, where you can’t easily tell if you’ve allowed an AI agent into a particular folder and it’s hard to know what a motivated agent could access, Variorum shows an icon on every item that has been shared with AI. You can also make notes and books private, which supersedes any general access grant and conceals their existence. Work with confidence knowing that AI access is visible always, impossible when not granted, and absent entirely when it is unwanted.

There are some other elements of Variorum that I hope will bring delight. I’ve always thought that notes apps should allow for book views to be composed from different notes at will, so I built that. With Variorum, the days where each note is its own file and there’s no way to read through them together have ended. Build books and gatherings by hand, by tag inclusion, by tag exclusion, or by whatever combination pleases you. The full-text search is fast: its cost scales with the number of matches, not the size of your library. Notes still edit smoothly at more than 10k words, while books can have more than a hundred thousand words without stuttering. Test it out by restoring “The Adventures of Sherlock Holmes” under the Help menu and scrolling through. Paragraphs you delete automatically move whole into the trash, so you can easily see what you got rid of. I love keyboard shortcuts, so almost everything has one. I’m grateful that an amazing writing editor was my first goal and that I achieved it before connecting it to AI because of the focus on quality it gave me.

I made Variorum 100% free to use locally because I don’t believe in renting possession of your own writing and because I wanted to give something back to the world. I really mean that you own your work — it is locally stored in an open format and you can easily AirDrop your library to another computer if you’d like to. When I release the mobile version there will be a paid sync option only because syncing is itself an ongoing cost. I’m deeply grateful to the open source coding community — Variorum only came into existence by standing on the shoulders of giants. I’m also grateful to the fanfiction community for having brought me so much joy and entertainment over the years. At a time when it feels like the whole world has been commoditized, people who share their creativity and passion freely online make the internet somewhere I want to spend time. In that spirit, I want Variorum to not only be the free option but the best one.

Being able to build and offer an app like Variorum — opinionated, personal, and creative — is one of the best parts of living in our AI era. That a single individual could make this app is also what lets me offer it for free. I’m a single human being, not a corporation, and my expenses are the same as everyone’s: shelter, food, and fun. I can support myself and all of my agents with my job — frontier AI isn’t cheap, but it is still a fraction of what it would’ve cost to hire software developers to build this app. Equally, knowing myself, I would not have taken the years that it would’ve required before AI to build this native macOS app in my spare time. I can’t measure the productivity gain in a percentage because the app simply wouldn’t have existed. In only four months, I’m amazed at how far this app has come, and it’s been fun to make. That’s what working with AI is like in 2026 — if you can dream it and you know what you’re doing, you can build it.

“If you know what you’re doing” is carrying a lot of weight in the previous paragraph, but I passionately believe that AI doesn’t have to be synonymous with slop and low-effort projects. Variorum is an ambitious effort that feels like a real accomplishment for both me and AI — it’s amazing what a single developer and a stochastic parrot can accomplish together. I want to work towards a version of the future where instead of AI replacing people, people are accomplishing more with AI.

As I developed this app I found that it was an immensely joyful experience to not just build but invent, to see something new solve real problems of mine. Variorum has become a facet of my daily life that encourages me to write, an editor that works with how I think. I can’t put a price on how I find myself journaling and writing more; I just know that life feels richer now. On a more personal note, I lost my beloved dog Chai in June. Even when the sun had gone cold in my life, focusing on building this app kept me excited for new days. Variorum is dedicated to her, even though she couldn’t read.

Now, finally releasing Variorum into the world, I can proudly say that what I consider the best feature isn’t a feature at all but instead the sense that there’s a single person who really cares behind the app’s design, execution, and experience. I hope that you like it. I would love to hear any of your thoughts, issues (yes, really, I want to fix them), and feature requests.

Thank you for trying Variorum,

Lillian