A consumer app – call them Relay – came to us after two agencies and every major ad platform had pushed their cost per install past £11. Their brief was one sentence: five hundred real users who'd still be there in week four.
The setup
We matched the brief to 18 communities across WhatsApp, Telegram, and Discord – founder groups and product communities in London, Lagos, Berlin, and Toronto whose member profiles overlapped Relay's early adopters. Fourteen admins approved the brief; four declined it as a poor fit for their group. Those declines cost Relay nothing, and they're the reason the fourteen that ran converted.
Each community got its own tracked link and promo code, with copy written in that group's register – the version posted to Lagos Tech UK read nothing like the one in Berlin AI Collective, because groups have voices and members can smell a paste-in from orbit.
The numbers
Over eleven days: 21,400 members reached, 1,930 link taps, 507 installs. Blended CAC came in at £4.20 – roughly a third of what paid social had been costing – and 62% of installed users were still active at day 28, against 31% from ads. Promo redemption ran 12% where codes were included.
The best-performing community wasn't the biggest. It was a 950-member group whose admin rewrote our copy in his own words. Trust beat reach by a factor of four.
What we'd tell the next brand
Let admins edit. The placements where admins adjusted the copy outperformed verbatim posts roughly 2:1. The admin knows what their room responds to – that judgment is the product you're buying, not the reach. Numbers here are from a pilot cohort and one campaign; treat them as a case, not a benchmark.