Best flashcard app for startups

There are roughly 40-60 flashcard apps in existence, but fewer than 15 meaningfully target the startup/team learning use case. The dominant players (Anki, Quizlet, RemNote) were built for students or personal knowledge management, so they fail startups on three fronts: (1) collaborative features are awkward or non-existent, (2) team permissioning and shared decks require workarounds, and (3) integration with tools startups actually use (Slack, Notion, Figma) is either missing or half-baked. The real gap is in the intersection of team learning and company culture—startups want to turn their best practices, customer insights, and domain knowledge into rapid onboarding and retention, but existing tools force them to choose between personal recall and team knowledge. A shipper focused here should prioritize: frictionless team deck creation from existing company docs, one-click Slack integration for distributed teams, and smart spaced repetition that surfaces company-specific knowledge during relevant workflows. Startups also care about retention metrics and cohort learning analytics, not just individual recall scores.