How EU Startups Should Actually Compare Speech-to-Text APIs for Invoice Processing

A technical guide argues that EU startups should evaluate speech-to-text APIs based on cost per accepted invoice rather than advertised per-minute pricing. The approach involves routing providers like OpenAI, Deepgram, AssemblyAI, and Google Cloud through a common interface and testing them against real supplier audio recordings. A small corpus of around 20 carefully chosen clips — covering invoice numbers, VAT identifiers, dates, and currency codes — is recommended to expose meaningful accuracy failures. EU data-handling compliance is treated as a hard disqualifier rather than a soft scoring factor. The framework emphasizes that a cheap transcript which corrupts a VAT number or total has no practical value, making accuracy-adjusted cost the only meaningful metric.