We study the large-scale experimental rollout of a platform that reduced search and matching frictions in Ugandan agricultural markets by connecting buyers and sellers. Market integration improved substantially: trade increased and price gaps fell. Interpreting the experiment through a trade model, we estimate treatment effects accounting for equilibrium changes that impact control markets. The intervention reduced fixed trade costs by 21% and increased trade flows between treated markets by 6% and across all markets by 1%. Scale economies shaped engagement: few farmers used the platform, but equilibrium price convergence from improved arbitrage by larger traders passed through to farm revenue.