An open foundation layer for Adaptive Design Systems.

About the IPAX Score

The IPAX Score translates normative and perceptual criteria into an intuitive format that helps designers make better decisions beyond basic compliance.

It is the reference implementation behind IPAX Foundation Layer by Kambrica, a UX consultancy working on Design Systems complexity since 2011. IPAX Foundation Layer is currently the only source of financial support for IPAX development.

Scores 0 and 1 are neither legible nor acceptable for text.

Zero means the contrast is below APCA Lc 15, which APCA treats as invisible for many users. A score of 1 means the text is between APCA Lc 15 and Lc 30: still below the WCAG 2 minimum acceptable contrast, meeting just the absolute minimum for any non-text that needs to be discernible and differentiable.

Scores 2, 3 and 4 correspond to accessibility compliance.

They indicate whether a pair meets legal and technical thresholds for readability. Reaching 3 means the design is "safe": it passes basic WCAG AA 4.5:1 contrast requirements.

Scores 5 and 6 describe design quality.

They represent combinations that are not only readable, but stable and suitable for sustained use in real interfaces. IPAX introduces penalties for halation, glare and chromatic fatigue, so that high scores reflect not only contrast performance, but also real reading comfort.

About the Project & Author

IPAX is an independent, open-source initiative developed by Santiago Bustelo, and was officially presented at Rosenverse by Rosenfeld Media.

Santiago started as an interaction designer in 1996. To contribute to the professional community, he founded the local chapter of the Interaction Design Association (IxDA) in Buenos Aires in 2009, and served as the first IxDA Regional Coordinator for Latin America, starting in 2010. That same year, he co-founded the Movimiento de Diseño Inclusivo (Inclusive Design Movement).

At the movement's launch event, he ran a live accessibility demo: Pablo Vázquez, who is blind, navigated two versions of the same page with a screen reader, one semantic and accessible, the other not, while Santiago walked the audience through what made the difference. For many in the room, it was the first time they had seen a blind person use the web.

He is Design Director at Kambrica, a strategic UX consultancy based in Buenos Aires, Argentina.

Sister Project: JSOL

Porting the IPAX scoring algorithm beyond JavaScript is the next step on the roadmap. That is why the core is pure calculation: no I/O, no knowledge of APCA, dictionaries or display formatting. The orchestrator receives the APCA engine, the font lookup and the dictionary as arguments, and only formats the output. A JS, PHP or Python runtime can replicate that integration layer: read the JSON SSOT, do the APCA lookup, pass everything in.

To make that port verifiable, IPAX relies on JSOL (JavaScript Source of Logic), a language Santiago is developing that currently compiles to JavaScript, Python, PHP and TypeScript, and is self-hosted: its own compiler is written in JSOL. The same algorithm, specified once, produces identical results on every target. This is the approach proposed in W3C WCAG3 issue #924 for the contrast algorithm itself.