ABSTRACT Startup accelerators have emerged as a prominent mechanism for supporting early-stage ventures, yet questions persist regarding their effectiveness. This study addresses the gap in understanding by investigating whether accelerators promote the growth of all startups or only those already successful. Leveraging web-search traffic data as a proxy for startup growth, trend analysis is used to assess the impact of acceleration. Using a sample of 103 startups from Y Combinator from 2017 and 2018, the analysis reveals that accelerators aid startups regardless of their pre-acceleration growth status (i.e. growing, stagnating or declining). Furthermore, non-growing startups selected for acceleration exhibit better chances of achieving growth post-acceleration compared to already growing counterparts. These findings add important insights into the understanding of accelerators’ effectiveness, demonstrating that accelerators work for all selected startups, not only for those already successful. Our findings offer two important practical implications: policymakers and stakeholders should continue supporting accelerators due to their positive impact on startup growth and reducing uncertainty; startups should focus on their future potential and vision when applying for an acceleration program. Using the introduced approach, future research could compare the effectiveness of accelerators offering offline and online programs, targeting specific industry sectors, and across different periods.