How RoboKiller grows

Screen each app or category on three lenses: (1) size: the product must plausibly reach tens of millions of dollars in revenue, avoiding a long tail of zombie apps doing a few hundred thousand each; (2) competition: a 'Goldilocks' market where you can take real share, e.g. RoboKiller was the leading independent spam blocker with carriers not invested and no big adjacent entrants; skip VPNs (everyone spends heavily on paid, so unit economics fail) and personal finance/budgeting (banks bid on the same keywords with far higher LTV); (3) existing demand vs. new category: existing demand allows ASO and performance marketing to pay back right away, while a new category means running at a loss to build demand.

As the largest US spam blocker, RoboKiller had unique data on spam calls and texts. It published regular reports (how many spam calls Americans get per month, how it is growing), worked with reporters to help them cover the issue, and shared data with the FCC and FTC, which lacked good data. No single article drove installs directly, but accumulated coverage built brand and organic lift.

Integrated a data broker removal service into RoboKiller as an upsell: sell users into the base spam-blocking subscription first, then offer the add-on, since it solves a related privacy problem.

Pick one or two key metrics per product (more creates noise) that show the product delivering its value. For RoboKiller it was passive: is the user getting spam calls and are we blocking them, plus 'did we get one wrong?' For TapeACall it was an action: did they record a call. A misclassified call became the trigger for proactive retention outreach.

Apple limits on user-level call data and the company's own privacy layer made personal stats hard, so RoboKiller showed stats across the whole user base (millions of calls blocked this month) to prove the background app was working.