Affirm’s Upfunnel Migration Turns Two‑Month Experiments Into Four‑Day Rollouts
Affirm rewrote its high‑traffic "upfunnel" surface from a Python monolith into a Kotlin microservice, collapsing a noisy config table and cutting experiment setup from two months to four days. The move also slashed 99th‑percentile latency by 47% and reduced configuration rows from hundreds of millions to a few million, unlocking faster iteration for merchants.