A-Alpha Bio vs Chai Discovery (2026)
Both use machine learning to design antibodies, and they build their models on different foundations. A-Alpha Bio starts from measurement: its AlphaSeq method records protein to protein interactions by the million, and its AlphaBind models are trained on that data to predict binding from sequence, with each design measured again to sharpen the models. The data engine is the thing A-Alpha is built around. Chai Discovery starts from foundation models, licensed to research teams as a product across three published generations, with a customer specifying the target, epitope and antibody format and designing many targets itself. A-Alpha is the one for a team that wants designs grounded in a vast measured interaction dataset and is open to a collaboration. Chai is the one for a team that wants to run published, improving models itself.
- Designs grounded in AlphaSeq, a measurement method the company says has recorded over a billion protein interactions.
- A loop where every AlphaBind design is measured experimentally to validate and refine the models.
- A roster of blue chip collaborators, including Bristol Myers Squibb, Amgen and Gilead.
- Foundation models licensed as a product, with three published generations and an open weights structure model.
- Customer driven design across many targets, with monoclonal and VHH formats and species cross reactivity.
- A fit for a team that wants to design itself rather than work through a collaboration.
This comparison is published by AI Health Index, an independent research platform that compares healthcare AI vendors objectively. A-Alpha Bio and Chai Discovery are each graded against the same capability taxonomy, from each vendor's own public materials and the regulatory record, under the AI Health Index verification standard. No vendor pays for placement, and no vendor has reviewed this page. How this evidence is graded
Plain facts
| Fact | A-Alpha Bio | Chai Discovery |
|---|---|---|
| Primary category | Drug Discovery AI | Drug Discovery AI |
| Founded | Not recorded | 2024 |
| Headquarters | Seattle, Washington, United States | San Francisco, California |
| Website | aalphabio.com | chaidiscovery.com |
Side by Side
Each record in one paragraph
Written to be quoted whole. Each paragraph states what the AI Health Index verified about the vendor, with the caveats attached. Generated from this pair’s live capability grades, so it moves when a grade moves.
The AI Health Index records no top capability grade for A-Alpha Bio on any axis it scores. Set against Chai Discovery, A-Alpha Bio does not grade higher on any scored axis, though the two are level on several axes, including Model and Technology Transparency, Clinical and Operational Evidence and Security Certifications and Trust Center. Its thinnest published disclosure sits on several axes, including AI Safety and PHI Stewardship, HIPAA and BAA Posture and Security Certifications and Trust Center. Grades reflect evidence the AI Health Index could verify at the last review, so a low grade records disclosure the vendor has not published rather than a capability it has been shown to lack.
Source: AI Health Index, October 2026
The AI Health Index awards Chai Discovery its top capability grade on AI Centrality, AI Governance and Bias Disclosure and Setting and Specialty Coverage. Set against A-Alpha Bio, Chai Discovery grades higher on several axes, including AI Centrality, Autonomy and Oversight Model and Model Supply Chain Disclosure. Its thinnest published disclosure sits on Security Certifications and Trust Center and EHR and Interoperability Depth. Grades reflect evidence the AI Health Index could verify at the last review, so a low grade records disclosure the vendor has not published rather than a capability it has been shown to lack.
Source: AI Health Index, October 2026
Questions buyers ask
Should we choose A-Alpha Bio or Chai Discovery?
The AI Health Index grades Chai Discovery higher than A-Alpha Bio on every axis that separates them, several axes, including AI Centrality, Autonomy and Oversight Model and Model Supply Chain Disclosure. A-Alpha Bio does not grade higher on any scored axis.
Where do A-Alpha Bio and Chai Discovery differ most?
The widest separation the AI Health Index records between A-Alpha Bio and Chai Discovery is on AI Governance and Bias Disclosure, where A-Alpha Bio grades D and Chai Discovery grades A. That axis sits in the Regulatory and Compliance group, so it should carry the most weight for a buyer whose binding constraint is where regulatory exposure sits and who carries it.
Where do A-Alpha Bio and Chai Discovery grade the same?
The AI Health Index grades A-Alpha Bio and Chai Discovery the same on several axes, including Model and Technology Transparency, Clinical and Operational Evidence and Security Certifications and Trust Center. Neither holds an advantage the index can evidence on those axes, so they should not carry weight in a selection between these two.
What have A-Alpha Bio and Chai Discovery not disclosed?
At the last review, at least one of A-Alpha Bio and Chai Discovery published thin or absent detail on several axes, including AI Safety and PHI Stewardship, HIPAA and BAA Posture and Security Certifications and Trust Center. The AI Health Index treats an absent disclosure as a gap in the public record rather than a failure of the product, so these are the axes to get in writing during diligence instead of inferring from the grade.
Related comparisons
Other published head to head assessments involving these vendors or their closest peers. The full set for this category is on the Drug Discovery AI page.
Both records were reviewed in October 2026. Neither publishes a price; A-Alpha works through partnerships and funded programs, while Chai sells model access through agreements.
Ask both how a program's data is kept separate from other customers' work, and for design success rates on targets like yours with the denominators attached.