InvoiceKoi

InvoiceKoi is invoicing for self-employed tradespeople and small service businesses who'd rather finish the paperwork at the job than at the kitchen table. On an Android phone you save clients and your own rates, build an estimate, collect the client's signature on screen, and turn the estimate into the invoice when the work is done, without retyping. Invoices go out as PDFs by email, WhatsApp, Telegram or text, and clients can pay by card through a Stripe link if you set one up. Core invoicing works with no signal and no account. You can set up your business and write drafts for free, but issuing numbered invoices, estimates and receipts needs a subscription, listed at $99.99 a year or $9.99 a week on the US store. There's also a free browser invoice generator for the US and UK with no account or watermark. The iPhone app is in App Store review. InvoiceKoi is run by Fang, a software company registered in Singapore.