Analysis
Weflayr, a Paris-based startup, closed a $2.5 million pre-seed round led by 13books Capital, with Founders Future, Kima Ventures, Plug and Play, Station F Ventures, General Catalyst scout Roxanne Varza and a group of angel investors also participating.
The product lets AI companies benchmark models against their own production data, approve trusted models, set routing rules, and match each new request to similar previously benchmarked calls -- tying inference decisions directly to cost and margin across customers and features rather than leaving model choice to a single default.
Why inference routing is becoming its own category
As companies run workloads across OpenAI, Anthropic, open-weight models and more, picking the right model per request rather than per application has become a cost and quality problem of its own. Weflayr says its first deployment cut inference costs more than 55% at equivalent quality and delivered roughly 15 percentage points higher relative quality at the same cost compared with routing everything to a single frontier model. 13books Capital partner Mike McFadgen framed the opportunity as building an independent intelligence layer at a moment when AI inference is becoming critical infrastructure in its own right.
Weflayr is entering a field that already includes OpenRouter, which routes requests across dozens of hosted models, and smaller specialists like Martian and Not Diamond that also sell model-selection logic as an API. The risk for a $2.5 million pre-seed company is that this category attracts well-funded entrants quickly once a buyer pattern is proven, and Weflayr's single-deployment numbers have not yet been tested at the multi-customer scale its larger competitors already operate at. However, the founding team's background is a point in its favor: Romain Mazeries, Mangopay's former CEO, ran payments infrastructure at scale, and Noe Achache, previously head of AI engineering at Theodo Data & AI, has applied-AI delivery experience most infra-only founders lack.
The pair are using the round to expand engineering and research and push into the US market, where most of the routing competition already sells -- a harder market to break into than the European seed-stage circles that just backed them.