InvoiceKoi is an Android invoicing app for independent tradespeople and small service businesses. Create estimates, invoices and receipts, save clients and a price book of your rates, track time and expenses, scan receipts, and share PDF documents. Estimates can become invoices without retyping, and deposits and part payments can be recorded.

Core invoicing and PDF creation work offline. AI features, cloud backup and payment collection need an internet connection. Setting up and drafting are free; issuing new documents requires a weekly or yearly subscription. The website also offers a separate free browser invoice generator with no account or watermark. Built by Fang Ventures Private Limited in Singapore.