Sane Labs Synth-2

Small models that read before they answer.

Four models, each larger than the last, none of them inheriting a single parameter from anywhere else. The thesis does not change with scale: put the knowledge in the context, not in the weights — then the model's job is to read carefully and to stop at the edge of what it was given.

Models
4
Largest
1.23B
Published
2
Borrowed weights
0
01

The models

Two are on Hugging Face and can be downloaded and run on a CPU today. One is kept private. One is still training.

46.7Mparameters

Sane-47M

Published

The first one that worked. It knows what it is, holds a short conversation, and — the useful part — reads a supplied <|context|> and copies the right value out of it, including out of noisy search results full of distractors, and says so when the answer is not in the passage.

Shape
12 × 512
Context
1024
Tokenizer
own BPE, 16k
Trained on
≈4.4B tokens
Hardware
2×T4 → TPU v5e-8
Weights
fp16, 105 MiB
118.5Mparameters

Sane-118M

Published

The same design 2.5× over, sharing a tokenizer with Sane-47M. Six hours on a TPU v5e-8 on a WSD schedule — and it clears GPT-2 small on two of the three tasks it was measured against, on a fraction of GPT-2's budget. The third it loses, which is also on the card.

Shape
15 × 768
Context
1024
Trained on
≈3.6B tokens
Hardware
TPU v5e-8, ~6 h
Weights
fp16, 249 MiB
Zero-shot · 200 examplesSane-118MRandomGPT-2 small
HellaSwag · acc_norm36.025.0~31
ARC-Easy · acc47.525.0~44
LAMBADA · acc22.0~0~33
~500Mparameters

Sane-500M

Private

The step between the small models and Synth-2, and the reason there is one: it is the check that the recipe survives past a hundred million parameters. Trained, kept private, not released.

1.23Bparameters

Synth-2

In training

The current work, and the first one carrying the idea in its architecture rather than in its training data. A small head on every layer predicts the model's own error for each token, so an answer can show which span to check rather than asking to be trusted whole. It reads a search results page and answers only from it.

Shape
24 × 768
Active
~330M of 1.23B
Experts
12 + 1 shared
Context
8k → 32k
Stack
JAX · TPU v5e-8
02

Alongside

unreleased

Sane Studio

Not released

A parallel project, not a model: a desktop agent that does the work on your own machine, with your own model keys — editing a project and running commands in it, answering from your own folders, reachable from a phone.

Still in development and currently not published anywhere. It is listed here because it is part of the work, not because there is anything to download yet.
03

Contact

Every figure on these pages comes from a measurement that can be repeated. If one looks wrong, saying so is worth more than a compliment.

Sane-47M and Sane-118M are released under the Sane Community License 1.0.
Sane Labs · 2026