Spillmark - 2026 Pricing, Features, Reviews & Alternatives

Spillmark is a cloud-based geo holdout incrementality testing platform built for brands that sell on Amazon and advertise on Meta (Facebook/Instagram). Rather than reporting attributed sales, it measures the actual incremental Amazon sales caused by Meta ad spend by running geo holdout tests with pre-locked test designs, preventing post-hoc modifications that can compromise result validity. Each completed test is stored with its test dates, measured lift, and uncertainty range, giving teams a reliable, auditable record of causal ad performance.

The platform is structured around two core functions: incrementality testing and supporting financial calculators. On the testing side, Spillmark produces MMM calibration outputs compatible with Robyn and Meridian, making it directly usable by brands running or calibrating marketing mix models alongside their incrementality programs. On the calculator side, Spillmark provides a free suite of tools covering Product Margin, Amazon FBA Fee, Break-Even ROAS and ACoS, TACoS and Blended ROAS, Holdout Test Sample Size, Incremental ROAS, and Marginal ROAS. These calculators connect margin economics, ad efficiency targets, and incrementality results into a unified analytical workflow.

Spillmark is relevant to e-commerce brands, Amazon marketplace sellers, and consumer brands running paid social campaigns who need to move beyond last-touch attribution and ground advertising decisions in causal measurement. The transparent lift calculation methodology and pre-locked test design make it suited for teams that require defensible, reproducible results for both internal reporting and MMM model inputs.