How a Two-Sided Marketplace Can Build Trust on Both Sides With Social Proof

The Challenge

A niche two-sided marketplace connects independent service providers (e.g., home repair specialists) with customers booking one-off jobs. Like most marketplaces, it faces the classic cold-start problem from both directions: prospective customers hesitate to book with a provider who has no visible track record, while prospective providers hesitate to list on a platform that doesn't yet show active buyer demand. Each side's confidence depends on the other side already being present and active — a chicken-and-egg trust gap that generic single-sided social proof tactics don't address.

Most social proof playbooks are written for one-sided businesses: a single seller convincing many buyers. A marketplace needs to build credibility for anonymous, independent third parties (individual providers) it doesn't fully control, while also showing overall platform liquidity to reassure both sides that the marketplace itself is active and worth using.

Why Generic Social Proof Falls Short

An initial attempt applied a standard e-commerce-style 'X people booked this week' banner to the whole platform. It didn't move buyer conversion much, because it answered the wrong question — buyers weren't unsure whether the platform had bookings in general, they were unsure whether this specific provider was trustworthy for their specific job.

The Approach

The team split social proof into two distinct layers: provider-level trust signals for buyers making a booking decision, and platform-level liquidity signals for providers deciding whether to join or stay active.

• Provider profile pages carrying aggregated reviews and completed-job counts specific to that provider, via NotiProof's review aggregation, rather than platform-wide averages
• Booking notifications on category browse pages showing recent, real bookings within that specific service category and region, helping buyers gauge active demand for providers like the one they're considering
• A separate set of onboarding-flow notifications for prospective providers, showing recent buyer activity and successful payouts to other providers in their category, to demonstrate the marketplace has real, current demand worth serving

Implementation

The marketplace's custom-built platform used NotiProof's JavaScript SDK directly (rather than a CMS plugin), with two separate notification configurations: one embedded in the buyer-facing booking flow, and one embedded in the provider onboarding and dashboard flow. Keeping these fully separate was necessary so buyer-facing proof never leaked into the provider's view and vice versa, since each audience needed different reassurance.

What Was Measured

On the buyer side: booking conversion rate per provider profile page and first-transaction completion rate (whether a booked job was actually completed, a proxy for whether buyer trust translated into a real transaction). On the provider side: sign-up completion rate through onboarding and time from a new listing going live to its first booking. Both sides were tracked separately in NotiProof's analytics and cross-referenced with the marketplace's internal transactions database.

Results

Buyer-side booking conversion improved on provider pages carrying provider-specific reviews and completed-job counts, and first-transaction completion rate also trended higher — consistent with marketplace research showing granular, individual-level trust signals outperform platform-wide aggregates for peer-to-peer trust decisions. On the provider side, sign-up completion improved after onboarding began showing real recent buyer activity in the provider's category, and new listings reached their first booking faster on average.

What Did Not Work

Platform-wide, undifferentiated activity banners (as noted) underperformed for buyers making a provider-specific decision. The team also tested showing provider earnings figures to prospective buyers, thinking it would signal popularity; this was quickly reversed as it felt irrelevant and slightly uncomfortable to buyers, who cared about service quality and reliability, not a stranger's income.