Why I stopped renting my financial tools and built LockMargin
One evening, I opened my banking app and added up what I was paying for software. Invoicing, time tracking, basic project management. It was over $25 a month. Nearly $300 a year.
And for what? My clients' financial data, bank details, and project histories were sitting on servers I had zero control over. I was paying a "privacy tax" to companies whose primary goal was to extract recurring revenue from me, not to protect my business.
At some point, I got tired of complaining about it and started writing code. I decided I'd rather build the tool than keep renting it.
The Constraint That Shaped Everything
From day one, there was one thing I refused to compromise on: no cloud. I don't trust it, and neither should you. If the internet goes down, your business shouldn't stop.
I specifically avoided building another heavy Electron wrapper. I chose Rust and Tauri 2.0. Rust lets me sleep better because whole categories of memory bugs simply disappear. Tauri keeps the installer tiny. Your data never leaves your machine unless you explicitly decide it should.
The Reality of Getting Security Right
Pretty screens are nice. Getting security right took much longer.
Somewhere around migration number 47, I started wondering whether building my own finance software had been a terrible idea. Every new feature touched three other systems. Security requirements kept expanding. The invoicing logic wasn't the hard part anymore — protecting the data was.
I didn't roll my own crypto. That would be stupid. LockMargin uses AES-256-GCM. The encryption key is derived using PBKDF2-HMAC-SHA256 and stored exclusively in the Windows Credential Manager. If somebody walks away with your laptop, opening the database won't be enough to read your financial data. A stolen laptop shouldn't automatically mean a data breach.
No Subscriptions. No Double-Entry Hell.
Most software companies want another monthly payment. I refuse to be one of them. LockMargin is a one-time payment ($59 Standard, $149 Agency). You buy it. You own it. No login screen phoning home.
I also left out a lot of accounting features on purpose. I kept asking myself: would a freelancer actually use this every day? The answer was no to double-entry bookkeeping. Yes to time tracking that doesn't make you hate yourself, and reactive recurring invoices that actually work without complex cron jobs.
What's Next
The core pieces are finally working the way I wanted them to. The encryption is audited, and the command palette (Cmd+K) is ready to speed up your workflow.
If it helps you spend less time fighting software and more time doing actual work, I'll consider it a success.
Built independently. From Ukraine.