Free Invoice Generator - A free invoice generator for startups
ChargeOver - ChargeOver automates recurring billing, subscription billing, & payment acceptance. A SaaS that integrates with Xero, Quickbooks, & has an API. Free trial.
Ramp Receipts - Create a receipts/invoice dashboard for Stripe
MinuteDock - Web-based time tracking software designed to integrate with the Xero accounting package.
Envoice - Send invoices and get paid on Paypal, Payoneer, Stripe and Square.
Elorus - A super-easy online invoicing & time tracking software