Model family

ESM (EvolutionaryScale and Biohub protein models)

Family overview — summarizes releases; licenses and availability belong to each release.

Maintained by Biohub (Chan Zuckerberg Biohub, Inc.)1 2, EvolutionaryScale (original developer; now part of Biohub)5 6 7

Protein language models developed by EvolutionaryScale and, since its team joined Biohub in November 2025, released by Biohub. The line includes ESM3 (June 2024), a generative model that reasons over protein sequence, structure, and function, with a largest version of 98B parameters and a small open model; ESM C (ESM Cambrian, December 2024), representation models at 300M, 600M, and 6B parameters; and, from May 2026, ESMFold2 structure prediction models and sparse autoencoders built on ESM C.5 6 3 1 10 9

Last reviewedSep 29, 2026Entry updated Sep 29, 2026Documented release Jun 25, 2024

Releases assessed

Each release is assessed on its own. This family has no family-wide openness label.

Releases in the ESM (EvolutionaryScale and Biohub protein models) family
Release	Weights	Tier (USASI rubric v0.1)	License	Released
ESM3 open small (esm3-sm-open-v1)	Weights: Public	Model-disclosure tier (USASI rubric v0.1): Open-weight	MIT	Jun 25, 2024
ESMC 6B (ESM Cambrian)	Weights: Public	Model-disclosure tier (USASI rubric v0.1): Open-weight	MIT	May 2026

What it is useful for

Protein representation learning and fine-tuning (ESM C), protein generation from partial sequence, structure, and function prompts (ESM3), and structure prediction for proteins and other biomolecules (ESMFold2).3 1 4

Run and use notes

Documented facts only. No hardware or performance claims are made without a cited source and stated assumptions.

The ESM3 README lists medium (7B) and large (98B) ESM3 models that are accessed through Biohub, with only the esm3-sm-open-v1 weights on Hugging Face; the hosted API moved from forge.evolutionaryscale.ai to biohub.ai, and the esm SDK still uses Forge class names.3 1

Organization context

Provenance and derivatives

ESM3 was trained on 2.78 billion natural proteins (771 billion unique tokens at its largest scale); ESM C was trained on protein sequences from UniRef, MGnify, and the Joint Genome Institute. ESMFold2 is built on ESMC 6B language model embeddings.3 6 1

U.S. eligibility

Project eligibility rests on documented governing or maintaining entities, not on contributors.

Eligible · basis: U.S.-governed project

The models were developed by EvolutionaryScale, PBC, whose former terms of use (effective January 15, 2025) gave a New York address, and are now published by Biohub; the repository license names Chan Zuckerberg Biohub, Inc. as copyright holder. The IRS lists Chan Zuckerberg Biohub Inc in Redwood City, California as a 501(c)(3) organization. Eligibility of each release is assessed on the release record.8 2 1 11

Assessed Sep 29, 2026

Sources

1.
Biohub/esm README (formerly evolutionaryscale/esm) (external site: github.com)
Biohub · Repository · accessed Sep 29, 2026
2.
Biohub/esm LICENSE.md (external site: raw.githubusercontent.com)
Chan Zuckerberg Biohub, Inc. · License · accessed Sep 29, 2026
3.
ESM3 README (Biohub/esm, _assets/ESM3_README.md) (external site: raw.githubusercontent.com)
Biohub · Documentation · accessed Sep 29, 2026
4.
biohub/ESMFold2 model card (external site: huggingface.co)
Biohub · Model card · accessed Sep 29, 2026
5.
ESM3: Simulating 500 million years of evolution with a language model (external site: evolutionaryscale.ai)
EvolutionaryScale · Announcement · published Jun 25, 2024 · accessed Sep 29, 2026
6.
ESM Cambrian: Revealing the mysteries of proteins with unsupervised learning (external site: evolutionaryscale.ai)
EvolutionaryScale · Announcement · published Dec 4, 2024 · accessed Sep 29, 2026
7.
EvolutionaryScale (home page) (external site: evolutionaryscale.ai)
EvolutionaryScale · Official page · accessed Sep 29, 2026
8.
Terms of Use (historical) | EvolutionaryScale (external site: evolutionaryscale.ai)
EvolutionaryScale · Official page · accessed Sep 29, 2026
9.
Biohub launches first large-scale scientific initiative combining frontier AI with frontier biology to cure or prevent disease (external site: biohub.org)
Biohub · Announcement · published Nov 6, 2025 · accessed Sep 29, 2026
10.
Biohub releases a world model of protein biology (external site: biohub.org)
Biohub · Announcement · published May 27, 2026 · accessed Sep 29, 2026
11.
Exempt Organizations Business Master File Extract - California (eo_ca.csv) (external site: irs.gov)
Internal Revenue Service · Filing · accessed Sep 29, 2026

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