Best freelancer invoicing for solo founders

There are roughly 40-60 invoicing tools competing for freelancers' attention, ranging from accounting software (FreshBooks, Wave) to payment platforms (Stripe Invoicing) to minimal-friction players (Notion templates). The common failure pattern is feature bloat: most tools optimize for multi-person teams, tax compliance across jurisdictions, or enterprise workflows, leaving solo founders with clunky UI and unnecessary complexity. The real pain point isn't invoicing itself—it's the context switch. Founders need invoicing that lives where they already work (Slack, Discord, email), that syncs automatically to their payment processor without manual reconciliation, and that handles retainers/milestone billing without 10 setup steps. The gap exists at the intersection of speed, automation, and vibeflow: something that feels like it was built by a founder, for founders, not by accountants. A new entrant should focus on three things: (1) one-click invoice generation from project context (Slack message, GitHub commit, Loom video), (2) automatic payment reconciliation that actually works, and (3) a retention model around retainer/subscription invoicing (where founders actually bleed margin). The winner won't be the tool with the most features—it'll be the one that feels like a natural extension of how solo founders already work.