Chromaeus: a browser-based analytical platform for quantitative colorimetric measurement in digital chemistry...

Digital colorimetry is widely used in analytical assays but remains limited by inconsistent sampling practices, fragmented workflows, and insufficient analytical traceability. Here, we present Chromaeus (https://moullab.github.io/Chromaeus/), a freely accessible, browser-based analytical platform designed to enable quantitative digital colorimetry within a unified post-acquisition environment. The platform integrates fixed-area ROI sampling, zoom-invariant pixel extraction, multi-color-space analysis, and built-in calibration, regression, and analytical performance evaluation tools without reliance on dedicated instrumentation or proprietary software. The technical reliability of Chromaeus was first established through systematic benchmarking across image file formats, resolutions, and browser environments, demonstrating preservation of colorimetric integrity (ΔE < 1; ICC > 0.99). Its analytical applicability was then demonstrated using a green silver nanoparticle-based colorimetric assay for hydrogen peroxide, where digitally extracted metrics showed strong agreement with UV-Vis spectrophotometry, yielding comparable limits of detection and linearity. Robustness under realistic imaging variability was further evaluated using an independent colorimetric dataset acquired under different lighting conditions and across multiple camera devices, showing consistent quantitative behavior and alignment with reference RT-PCR trends. Finally, comparative benchmarking against commonly used tools (ImageJ, Photometrix, and Trigit) highlighted that Chromaeus uniquely enables integrated quantitative workflows rather than simple color extraction. Together, these results position Chromaeus as a generalizable framework for standardized, instrument-independent quantitative colorimetric analysis across diverse application domains.