Sofía Castro

Sofía built her first online audience by accident. In 2015 she was finishing a marketing degree at the Tec de Monterrey CDMX campus and posting beauty tutorials on Instagram in her free time. Within eighteen months the account had 80K followers, three brand collaborations, and a contract dispute with one of those brands that taught her two things: read the affiliate-payment terms carefully, and never trust the agency that introduces you to the brand to also represent you in the dispute. She finished the degree, paid off her CETES debt with one Black-Friday campaign, and went to work for a CDMX performance agency in 2018 with a very specific point of view about how influencer-affiliate deals get structured.

What she learned over the next five years isn't in any of the agency's case studies. It's in the gap between what a brand in Madrid thinks "the LATAM market" is and what a buyer in CDMX actually navigates — four payment-method ecosystems (CoDi, SPEI, OXXO, the dollar-denominated PayPal corridor for cross-border deals), three or four very different audience clusters in just Mexico (CDMX vs Monterrey vs Guadalajara vs the Spanish-speaking US, which she counts as a fifth-state of Mexican advertising even though the politics there are sensitive), and an influencer-economy that operates on Mexican Spanish slang that a Spaniard or a Colombian can roughly understand but cannot fluently produce. Between 2019 and 2023 she ran $4.8M of cumulative Mexican performance-affiliate budget and watched 100+ creators sign and break and re-sign agency deals.

She went independent in 2023 after the agency's third reorganisation in two years and the strategic-director seat she was promised went to someone the new managing partner had brought from Sao Paulo who didn't speak Mexican Spanish and didn't understand why that mattered. The independent practice started as influencer-side dispute mediation (which still pays the rent on a slow month), expanded into advertiser-side network selection, and is now also the writing on this site. She still consults for two of the brands she used to buy for at the agency. She still keeps her Instagram account active (it's down to 110K but still real) and runs the occasional affiliate offer through it as a sanity check on what's working in the market she writes about.