Custom Invoices & Quotations App
Cloud-based invoicing app for custom PDF invoices with automated emails.
The Custom Invoices & Quotations App is a cloud-native invoicing solution designed for small businesses and freelancers who need flexible, branded PDF invoices, automated email delivery, and reliable payment tracking. The application focuses on automating invoice generation, managing quoted estimates, and simplifying reconciliation, while ensuring data security and integration with payment providers.
SEO-targeted keywords: cloud invoices app, PDF invoice generator, automated invoice emails, payment tracking, invoice API, custom quotations.
Core capabilities include template-driven PDF generation with branded headers and line-item details, automated delivery of invoices via email, webhook notifications for payment events, and an admin dashboard for tracking outstanding invoices and aging reports. The backend uses FastAPI for serving REST endpoints, PostgreSQL for transactional storage, and cloud storage (S3-compatible) for storing generated PDFs and receipts.
Overview table:
| Capability | Description | Business Value |
|---|---|---|
| PDF Templates | Customizable invoice templates | Professional branded documents |
| Automated Email | Scheduled and triggered emails | Timely invoice delivery |
| Payment Tracking | Webhook-based reconciliation | Reduced unpaid invoices |
| Security | Auth & role-based access | Compliance & privacy |
Simple flow: Create Quote -> Approve -> Generate Invoice -> Send Email -> Track Payment
Implementation steps
- Design invoice templates and map line items to accounting categories.
- Implement backend endpoints for quote creation, invoice generation, and PDF rendering.
- Integrate with payment gateways (Stripe, PayPal) and configure webhooks for settlement events.
- Build automated email templates and retry logic for failed deliveries.
- Add reporting and export features for accounting reconciliation.
Challenges and solutions
- Handling partial payments and refunds: implemented ledger entries and a settlement state machine to model partial captures and refunds accurately.
- Ensuring invoice uniqueness and idempotency: invoice numbers are generated with deterministic prefixes and verified at creation time to prevent duplicates.
- Managing PDF generation at scale: used a rendering pool with caching of static assets and async job queues for heavy generation tasks.
- Cross-border tax complexity: provided configurable tax rules and line-level tax calculations with region-specific settings.
Why this app matters for SEO and business
Offering clear documentation, sample APIs, and case studies about reduced days sales outstanding (DSO) helps this project rank for high-intent keywords related to invoicing automation. For businesses looking to automate billing, reduce manual errors, and present professional invoices, this app provides a practical, extensible solution that integrates with existing accounting workflows.