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Open Source SaaS

Independent Contractor Invoicing Platform

Built an open-source SaaS invoicing solution for freelancers, emphasizing simplicity, privacy, and zero-cost operation with modern web technologies.

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This project demonstrates the power of radical product focus and user-centric design. Rather than competing with feature-rich accounting platforms, the invoicing application identifies a specific, underserved user need—freelancers who need to generate professional invoices quickly without unnecessary complexity. Built with Next.js, React, and Supabase, the platform prioritizes speed, simplicity, and privacy while maintaining a completely free, no-subscription model.

Skills

Next.js 14+React 19TypeScriptTailwind CSS v4SupabasePostgreSQLReact PDFshadcn/ui

Key Deliverables

  • Core invoicing with professional PDF generation
  • Client management and invoice tracking
  • Supabase authentication and row-level security
  • Payment status tracking for cash flow management
  • Privacy-first architecture with user data control
  • Vercel deployment optimization

The Problem

Invoicing friction in the freelance economy

Independent contractors and freelancers face unique challenges managing their billing processes. The market is saturated with invoicing solutions, but they fall into two categories: expensive enterprise tools designed for accounting departments, or feature-limited free tiers engineered to drive premium subscriptions.

This creates a gap for freelancers who need professional invoicing without complexity or recurring costs. They struggle with late payment management, administrative overhead consuming billable time, overwhelming feature sets they don't need, cost barriers impacting margins, and privacy concerns about storing sensitive data with third-party services.

Core Pain Points

  • Manual invoice creation consuming billable time
  • No simple way to track payment status
  • Existing solutions too complex for core needs
  • Monthly subscriptions impacting freelancer margins
  • Data privacy concerns with third-party platforms

Target User Needs

  • Generate professional invoices quickly
  • Maintain simple client database
  • Track payment status for cash flow
  • Export invoices as PDFs for delivery
  • Operate with minimal software overhead

Product Philosophy

Lightweight by design: Simplicity as a feature

Focused Feature Set

The application delivers exactly six core capabilities: simple invoice creation, client management, PDF generation, payment tracking, minimal interface, and privacy-first architecture. This restraint is deliberate. The application excludes time tracking, expense management, multi-currency support, recurring invoices, payment integration, and tax reporting—features that add complexity but don't serve the core user need.

Free Forever

No subscriptions, no hidden fees, completely free. This removes cost barriers and positions the tool as a public good rather than a profit center.

Privacy First

User data stays under their control, leveraging Supabase's open-source backend. Self-hosting option available for users requiring complete ownership.

Modern Stack

Built on proven technologies that enable rapid development and long-term maintainability without unnecessary complexity.

Technical Architecture

Modern simplicity: Proven tools without unnecessary complexity

Frontend Architecture

  • Next.js 14+ with App Router for SSR and code splitting
  • React 19 with component-driven architecture
  • Tailwind CSS v4 for rapid UI development
  • shadcn/ui for accessible, customizable components
  • Lucide React for lightweight icon system

Backend & Data

  • Supabase PostgreSQL for robust relational data
  • Row-level security (RLS) ensuring user data isolation
  • Supabase Auth for email/OAuth authentication
  • Version-controlled database migrations
  • React PDF for client-side PDF generation

Deployment & Infrastructure

Vercel optimization eliminates infrastructure complexity. One-click deployment from GitHub, automatic HTTPS, CDN distribution, and serverless function hosting. Zero-config production builds align with the lightweight philosophy—no complex server management or DevOps overhead.

Key User Flows

Streamlined workflows enabling quick success

Onboarding

  1. 1. Create account via email or OAuth
  2. 2. Enter contractor details
  3. 3. Optionally add first client
  4. 4. Create first invoice
  5. ~5 minutes to value

Invoice Creation

  1. 1. Navigate to "New Invoice"
  2. 2. Select or create client
  3. 3. Add line items
  4. 4. Preview and download PDF
  5. Friction-free workflow

Client Management

  1. 1. View all clients in dedicated page
  2. 2. Add/edit client information
  3. 3. View invoice history per client
  4. 4. Create invoices with pre-filled data
  5. Simple, focused

Security & Privacy Architecture

Data control at the foundation

Authentication

  • Supabase Auth managed
  • Email/OAuth providers
  • Secure session management

Authorization

  • Row-level security policies
  • Database-level access control
  • Users access only own data

Data Control

  • Open-source transparency
  • Self-hosting capability
  • HTTPS and encrypted transit

Market Positioning

Differentiation through radical simplicity

Competitive Advantages

  • Only invoicing—no feature bloat
  • True 'free forever'—no hidden upsells
  • Modern, maintainable tech stack
  • Open source—full code transparency
  • Privacy by design—user data control
  • Zero learning curve—immediate productivity

Ideal User Profile

Perfect for new freelancers needing their first invoicing solution, experienced contractors tired of bloated software, privacy-conscious professionals, developers wanting to self-host or customize, and anyone seeking a "no BS" approach.

Positioning

"The simplest invoicing tool for freelancers who just need to send invoices."

Key Lessons & Best Practices

Feature Restraint is a Feature

Saying 'no' to features creates focus and usability. Most freelancers need to send invoices, not manage a full accounting system.

Free Can Be Sustainable

Not every project needs monetization if it serves the creator's needs while building reputation and community goodwill.

Privacy as Positioning

Data control is increasingly valuable to users. Open-source transparency and self-hosting capabilities build trust.

Modern Defaults as Standard

Using current best practices (Next.js, React, shadcn/ui) provides long-term maintainability and developer satisfaction.

BaaS Acceleration

Supabase handles auth, database, and hosting concerns, enabling rapid development without infrastructure overhead.

Deployment Simplicity

Vercel + Supabase eliminates infrastructure management, allowing focus on product rather than DevOps.

Impact & Outcomes

Open Source

MIT licensed, enabling auditing, customization, and community contribution.

Community Impact

Serves freelancer community as a public good without paywalls or upsell pressure.

Portfolio Value

Demonstrates full-stack expertise, product thinking, and sustainable SaaS development.

Simplicity as Innovation

This project demonstrates that innovation doesn't always mean adding features—sometimes it means removing everything that doesn't serve the core user need. In a market dominated by feature-rich platforms competing for enterprise clients, this tool stakes out a defensible position: the simplest, fastest, most private way for freelancers to create invoices.

The technical implementation validates modern web development best practices, while the product philosophy validates user-centric design. For anyone building SaaS applications, this project offers a masterclass in scope management, technology selection, and product positioning.

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Contact Information

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Location

San Francisco, California, USA

Select a Date

October 2025

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