sd21-base-acutance

Stable Diffusion 2.1-base — byte-exact mirror

This repository is a byte-exact mirror of the stable-diffusion-2-1-base checkpoint. It exists because the original upstream is gone, and it is published so that a downstream application can keep verifying what it downloads.

Nothing here is modified. No fine-tuning, no re-quantisation, no re-serialisation. Every file is reproduced bit for bit; the SHA256 table below is the proof.

Why this mirror exists

As of 2026-09-03, an authenticated query to the Hugging Face API returns missing (not gated) for stabilityai/stable-diffusion-2-1-base and for stabilityai/stable-diffusion-2, and the Stability-AI/stablediffusion repository is gone from GitHub as well. The whole upstream was withdrawn — weights, model card and the license document alike.

Note for anyone diagnosing a similar problem: HTTP 401 from the Hub does not distinguish "gated" from "does not exist". Only an authenticated query settles it.

Provenance of the bytes

The consuming application pins hashes, not the repository id — the address is only a source of bytes, and the verdict is issued by SHA256. That is the reason a mirror is a safe substitute at all: the same bytes at a different address are still the same artifact.

Independent corroboration

A hash table proves that this copy matches the repository it was copied from. On its own it says nothing about whether that repository matches what Stability AI published — the upstream is gone, so there is no reference copy left to check against, and the claim "byte-exact" would otherwise rest on trusting a single intermediary.

Two mirrors settle it. Both were created before the upstream was withdrawn and before the repository these bytes were copied from even existed, so neither can be a copy of it:

Checked 2026-09-05 against the Hub API: lfs.sha256 for the three weight files (that field is the SHA256 of the content) and locally computed git blob ids for the eight small ones. No second copy was downloaded — the check costs nothing to repeat.

Five further mirrors also match, and are deliberately not listed: they were created after the withdrawal, so they may descend from the same intermediary. They are consistent, not independent — and a witness count is only worth what its weakest member is.

SHA256 of every file the application loads

Verify a local copy with sha256sum, or with any tool of your choice.

License — read this part

The weights are licensed under the CreativeML Open RAIL++-M License, and LICENSE in this repository carries its full text, including the use restrictions in Attachment A. Those restrictions travel with the model: if you redistribute it or a derivative, you must pass them on.

⚠ The bundled document is not the exact file that once shipped with SD 2.1, and saying so plainly matters more than looking tidy. The SD 2.1-base model card pointed at stabilityai/stable-diffusion-2/LICENSE-MODEL (Open RAIL++-M, dated 2022-11-24), and that file is no longer published by anyone — of eight SD 2.1 mirrors checked on 2026-09-03, none carried a license text. What you get here instead is the same license from the same licensor in its published form, dated 2023-07-26; its body is generic and makes no mention of any particular model. Substituting it visibly is honest; substituting it silently would not be.

Attribution

Original model by Stability AI. This repository claims no authorship over the weights — it only keeps them reachable and verifiable.

Not affiliated with, endorsed by, or sponsored by Stability AI. The name of the model is used here only to identify which checkpoint these files are, as the license requires the attribution to be kept and forbids any suggestion of endorsement.