Offline-First Invoicing App for Freelancers
What does LockMargin do? LockMargin is a local Financial OS for freelancers: time tracking, invoices, clients, projects and expenses in one encrypted SQLite file on your machine.
LockMargin is a local Financial OS for freelancers — meaning it is the software layer between you and your money. Your data stays on your machine. No cloud. No subscription. No account required.
Key Terms Explained
Offline-First
Application architecture that works without internet connection. Your data is stored locally and syncs only when you choose to.
AES-256-GCM
Advanced Encryption Standard with 256-bit key and Galois/Counter Mode. Authenticated encryption that keeps your client data unreadable without your password.
Partial Payments
Accept installment payments on invoices. Clients can pay in parts — set minimum amounts, track remaining balances, and auto-mark invoices as paid when settled.
Multi-Currency
Create invoices and track expenses in any currency. LockMargin handles conversions, formatting, and reporting across multiple currencies simultaneously.
Health Score
Real-time metric showing your business financial health. Combines paid vs. outstanding invoices, project profitability, and cash flow trends.
Client Portal
Dedicated interface where clients can view invoices, payment history, and outstanding balances without needing access to your full LockMargin workspace.
Get Paid Faster
I sent an invoice at 2 AM once because I forgot earlier. LockMargin generated the PDF in 3 seconds. Client paid on time. Never knew how close they came to getting two invoices (recurring bug, fixed at 2:15 AM). Compare with manual invoicing: LockMargin vs Excel/Google Sheets
Quick Invoicing
Full invoicing with status tracking, discounts, partial payments, and templates. Generate PDFs, draft .eml emails, and send with one click.
PDF + EmailRecurring Invoices
Reactive recurring engine — no cron jobs needed. Handles both invoices and expenses automatically when due.
No Cron NeededStripe Payment Links
Generate Stripe payment links directly from invoices. Clients pay in one click. No terminal, no extra fees.
1-Click PayTrack Every Minute
One of my clients uses expense categories in a way I still don't understand. But it works. I don't touch it. The Health Score tells you if you're actually profitable or just busy.
Time Tracking
Active session timer with start/stop, duration tracking, and billing status. Categorized entries with unbilled filters.
Active SessionsProjects
Track budgets, hourly rates, health scores, and color-coded status. Flexible billing — fixed fee, retainer, or hourly.
Health ScoreExpenses
Track expenses by category, attach receipts, set recurring items. Billable vs non-billable flags on every entry.
Receipt ReadyLedger
Full double-entry ledger view. Every transaction tracked, categorized, and reconciled automatically.
Full Audit TrailKnow Your Numbers
See your business clearly. Real Hourly Rate, Business Runway, Tax Shield, Profit Pulse, and client profitability ranking.
Real Hourly Rate (RHR)
Revenue per hour worked — track your true earning efficiency and make smarter pricing decisions.
RHR MetricBusiness Runway
Calculates months of operation based on current balance vs monthly burn. Know your financial runway at a glance.
Financial RunwayProfit Pulse + Tax Shield
Live margin tracking, cash flow visualization, and client profitability ranking. Tax rate definitions per country.
Live MarginDashboard v8
Your entire business, one screen. 8 KPI metrics, drag-and-drop widgets, real-time updates every 30 seconds.
Drag & Drop26 Financial Reports
From cash flow to tax readiness. Export to CSV or PDF. Profit & Loss, Client Profitability, Tax summaries, and 23 more.
CSV + PDFSleep Better
Your financial data is safer than in a bank vault. AES-256-GCM encryption, offline-first architecture, encrypted backups. If your laptop gets stolen, the thief gets a SQLite file full of garbage without your password.
AES-256-GCM Encryption
Field-level encryption with Argon2id key derivation. Keys stored in your system keychain.
Keyring StorageOffline-First Architecture
Your data lives on your machine by default. Not because we are against the cloud — because we believe you should choose. No telemetry. No forced cloud endpoints.
100% LocalBackups + Soft Delete
Auto-backups, full restore support, and soft delete on all entities. Accidentally deleted something? Undo in one click.
Undo FriendlyStealth Mode
Working in a coffee shop? One click hides all sensitive data. Your numbers, your privacy.
Privacy ShieldWork at Speed
Cmd+K opens 21 actions. No menu hunting. The app starts in under a second because I got tired of waiting for Electron apps to load. Rust-powered. No bloat.
Command Palette
Cmd+K opens 21 actions in 4 categories. Create, navigate, settings, help. No menu hunting required.
Ctrl+K / Cmd+KKeyboard Shortcuts
Every action has a keyboard shortcut. Advanced mode adjusts the UI density and visible complexity.
Advanced ModeRust-Powered Speed
Built with Rust. Opens in milliseconds. No bloat, no lag, no waiting for cloud sync.
Instant StartupDark / Light Theme
Automatic theme switching or manual override. Your eyes, your preference, your productivity.
Theme SwitchReal-Time Updates
Dashboard auto-refreshes every 30 seconds. No manual reload. Always see the latest numbers.
30s RefreshThe Integrity Engine — Invoicing you can defend in court
I once had a client ask me to "adjust" an invoice after sending it. The Immutability Guard prevented it. The client wasn't happy, but I slept fine. Every invoice is anchored to its source data. No silent edits, no "oops I changed the rate" after the fact.
Snapshot Billing
Snapshot Billing freezes your time data when an invoice is generated. Edit entries later? The sent invoice stays exactly as issued. Zero billing disputes.
Freeze on SendImmutability Guard
Sent invoices are sealed and cannot be silently altered. Ensures legal integrity of every document you send to clients.
Sealed DocumentsTraceability
Every invoice line item traces back to its source time or expense record. A full, always-available audit trail for your peace of mind.
Full Audit TrailTry Before You Buy
Explore LockMargin with realistic sample data. No account, no commitment.
Pre-filled Database
5 clients, 5 projects per 30 days, realistic invoices — all sample data to explore every feature.
All Features Visible
See the full Standard tier experience. Every report, every template, every tooltip.
Switch Anytime
Toggle between Demo and your real data in one click. No import/export needed.
Frequently Asked Questions
Can I create invoices without internet?
Yes. LockMargin works 100% offline. Create, edit, and export invoices without any internet connection. Perfect for travel, remote locations, or privacy-conscious workflows.
How does AES-256-GCM encryption work?
AES-256-GCM is authenticated encryption. LockMargin encrypts every field in your database with a key derived from your password using Argon2id key derivation. Even if someone steals your laptop, they cannot read your data without your password.
Can I export my data?
Yes, anytime. Export to CSV, PDF, or JSON with one click. No vendor lock-in, no export fees, no permission required. Your data belongs to you.
Do I need to pay monthly?
No. LockMargin Standard is a one-time $49 payment. Use it forever. No monthly fees, no annual renewals, no forced upgrades. Free updates for v1.x included.
Can I use LockMargin on multiple devices?
Standard license includes 1 device. Need more? Additional device licenses are available. Each device has its own encrypted database — no cloud sync required.
What happens if I stop using LockMargin?
Your data stays on your computer forever. Export anytime to standard formats (CSV, PDF, JSON). No account to delete, no subscription to cancel, no data held hostage.
Is there a refund policy?
Yes — the details live on the pricing page. Either way, your data stays on your machine and exports to CSV, PDF, or JSON. You are never locked in.
Ready to take control of your invoicing?
LockMargin is built for freelancers who want their data on their own machine. Pay once, own forever.
No subscription · No account required · Your data stays yours forever