Klirr vs Invoice as a Service

Zero-maintenance invoicing that generates beautiful invoices automatically

A FOSS invoicing tool built in Rust that generates beautiful PDF invoices for services and expenses with zero maintenance. Define your clients, services, and rates — klirr handles the rest. Designed for freelancers and solo consultants who want professional invoices without subscribing to a billing platform.

Simple invoicing REST API — send JSON, get a PDF

A dead-simple invoicing microservice. Send a JSON payload with your invoice data, get back a beautifully formatted PDF. No database, no accounts, no UI — just an API endpoint you can integrate into any stack. Self-hostable, Docker-ready, and perfect for developers who want programmatic invoice generation without a SaaS dependency.