Overview

Identity

Identity block not returned by the API for this entity.

Openness

Openness not classified yet — no sourced evidence to place this model in the ontology.

Key facts

Release date: Source:Hugging Face Hub (public pages, model cards, papers)T2observed 12 h agomedium
Model card: huggingface.co/cerebras/Step-3.5-Flash-REAP-121B-A11B
Source:Hugging Face Hub (public pages, model cards, papers)T2observed 12 h agomedium

Architecture

Architecture: Source:Hugging Face Hub (public pages, model cards, papers)T2observed 12 h agomedium
Model type: Source:Hugging Face Hub (public pages, model cards, papers)T2observed 12 h agomedium
Parameters: Source:Hugging Face Hub (public pages, model cards, papers)T2observed 12 h agomedium
Active parameters: Source:Hugging Face Hub (public pages, model cards, papers)T2observed 12 h agomedium
Weights dtype: Source:Hugging Face Hub (public pages, model cards, papers)T2observed 12 h agomedium
File size: Source:Hugging Face Hub (public pages, model cards, papers)T2observed 12 h agomedium
Library name: Source:Hugging Face Hub (public pages, model cards, papers)T2observed 12 h agomedium
Pipeline tag: Source:Hugging Face Hub (public pages, model cards, papers)T2observed 12 h agomedium
Hugging Face repo: Source:Hugging Face Hub (public pages, model cards, papers)T2observed 12 h agomedium

Capabilities

Modalities

Modalities unavailable.

Capabilities

Tool calling
Unavailable
Structured output
Unavailable
Reasoning
Unavailable
Vision
Unavailable
Audio
Unavailable
Fine-tuning available
Unavailable

No capability flags have been observed from a source yet — we do not infer them.

Languages: Source:Hugging Face Hub (public pages, model cards, papers)T2observed 12 h agomedium

Hardware fit37

Estimated

19 of 37 device × quantization combinations fit.

Run locally: your machine →

Estimated hardware fit
Hardware	Quantization	Device memory	Est. memory	Fits
Apple M3 Ultra	4bit	—	70.1 GB est.	Yes
Mac Studio (Apple M5 Ultra)	4bit	—	70.1 GB est.	Yes
Apple M2 Ultra	4bit	—	70.1 GB est.	Yes
Apple M1 Ultra	4bit	—	70.1 GB est.	Yes
Apple M3 Max	4bit	—	70.1 GB est.	Yes
Apple M4 Max	4bit	—	70.1 GB est.	Yes
Mac Studio (Apple M5 Max)	4bit	—	70.1 GB est.	Yes
MacBook Pro (Apple M5 Max)	4bit	—	70.1 GB est.	Yes
Apple M2 Max	4bit	—	70.1 GB est.	Yes
NVIDIA A100 80GB	4bit	80 GB	70.1 GB est.	Yes
NVIDIA H100 SXM	4bit	80 GB	70.1 GB est.	Yes
NVIDIA H100 NVL	4bit	94 GB	70.1 GB est.	Yes
NVIDIA DGX Spark	4bit	128 GB	70.1 GB est.	Yes
NVIDIA H200	4bit	141 GB	70.1 GB est.	Yes
NVIDIA H200 NVL	4bit	141 GB	70.1 GB est.	Yes
NVIDIA B200	4bit	180 GB	70.1 GB est.	Yes
AMD Instinct MI300X	4bit	192 GB	70.1 GB est.	Yes
AMD Instinct MI325X	4bit	256 GB	70.1 GB est.	Yes
NVIDIA DGX B200	4bit	1,440 GB	70.1 GB est.	Yes
Apple M1 Max	4bit	—	70.1 GB est.	No
Apple M4 Pro	4bit	—	70.1 GB est.	No
Mac mini (Apple M5 Pro)	4bit	—	70.1 GB est.	No
MacBook Pro (Apple M5 Pro)	4bit	—	70.1 GB est.	No
Apple M3 Pro	4bit	—	70.1 GB est.	No
Apple M1 Pro	4bit	—	70.1 GB est.	No
Apple M2 Pro	4bit	—	70.1 GB est.	No
Apple M4	4bit	—	70.1 GB est.	No
iMac (Apple M4)	4bit	—	70.1 GB est.	No
Mac mini (Apple M6)	4bit	—	70.1 GB est.	No
MacBook Air (Apple M5)	4bit	—	70.1 GB est.	No
MacBook Pro (Apple M5)	4bit	—	70.1 GB est.	No
Apple M2	4bit	—	70.1 GB est.	No
Apple M3	4bit	—	70.1 GB est.	No
Apple M1	4bit	—	70.1 GB est.	No
NVIDIA GeForce RTX 3090	4bit	24 GB	70.1 GB est.	No
NVIDIA GeForce RTX 4090	4bit	24 GB	70.1 GB est.	No
NVIDIA GeForce RTX 5090	4bit	32 GB	70.1 GB est.	No

Assumptions (6)

Estimated, not measured: weights = parameters × bytes/param × 1.15 runtime overhead.
bytes/param: 4bit = 0.5, 8bit = 1.0, fp16 = 2.0 (uniform quantization, no per-layer exceptions).
KV cache approximated at 0.5 GB per 8 192 tokens of context, independent of architecture (GQA/MLA models need less).
A model 'fits' when the estimate is at most the device memory minus 2 GB reserved for the OS and framework.
Mixture-of-experts models are estimated on total parameters (all experts must be resident); active parameters are ignored.
Device memory uses the largest configuration when several are listed (e.g. Apple silicon tiers).

Lineage

Open in Graph →

Explicit derived_from / fine_tuned_from / distilled_from relations stated by sources; artifacts collapsed by kind.

Papers1

arXiv:2510.13999Active
35

Timeline1

Full timeline →

11 Sept 2026
New modelModelStep-3.5-Flash-REAP-121B-A11BCerebras Systems
New model: Step-3.5-Flash-REAP-121B-A11B (Cerebras Systems)
huggingface
huggingface.co

Change history21

Temporal, append-only claims: a new observation closes the previous claim instead of overwriting it. Rewind the record with the as-of picker.

Viewing AI Atlas as of 12 Sept 2026 — attributes exactly as the atlas knew them on that day; later corrections are not shown.

Back to today →

Attributes as of 12 Sept 2026 22 claims in force

Release date: 25 Feb 2026
Openness: open-weights
License: Other
Architecture: Step3p5ForCausalLM
Parameters: 121B
Active parameters: 11B
Languages: en
Base model: stepfun-ai/Step-3.5-Flash
File size: 241.9 GB
Hugging Face repo: cerebras/Step-3.5-Flash-REAP-121B-A11B
Pipeline tag: text-generation
Model card: huggingface.co/cerebras/Step-3.5-Flash-REAP-121B-A11B
Downloads: 148
Likes: 15
Gated: No
Last modified: 2026-02-25T07:13:23+00:00
Library name: transformers
Downloads all time: 943
Model type: step3p5
Tags: transformers, safetensors, step3p5, text-generation, stepfun, MOE, pruning, compression, custom_code, en
Weights available: Yes
Weights dtype: BF16, F32

21 claims · 21 properties

Release daterelease_date1

Claim history for Release date
Value	Valid from → to	Status	Source	Confidence	Extractor
25 Feb 2026	11 Sept 2026 21:26 UTC → current	current	Hugging Face Hub (public pages, model cards, papers)T2	medium	deterministic

Opennessopenness1

Claim history for Openness
Value	Valid from → to	Status	Source	Confidence	Extractor
open-weights	11 Sept 2026 21:10 UTC → current	current	Hugging Face Hub (public pages, model cards, papers)T2	medium	deterministic

Licenselicense1

Claim history for License
Value	Valid from → to	Status	Source	Confidence	Extractor
other	11 Sept 2026 21:26 UTC → current	current	Hugging Face Hub (public pages, model cards, papers)T2	medium	deterministic

Architecturearchitecture1

Claim history for Architecture
Value	Valid from → to	Status	Source	Confidence	Extractor
Step3p5ForCausalLM	11 Sept 2026 21:26 UTC → current	current	Hugging Face Hub (public pages, model cards, papers)T2	medium	deterministic

Parametersparameter_count1

Claim history for Parameters
Value	Valid from → to	Status	Source	Confidence	Extractor
121B	11 Sept 2026 21:10 UTC → current	current	Hugging Face Hub (public pages, model cards, papers)T2	medium	deterministic

Active parametersactive_parameter_count1

Claim history for Active parameters
Value	Valid from → to	Status	Source	Confidence	Extractor
11B	11 Sept 2026 21:26 UTC → current	current	Hugging Face Hub (public pages, model cards, papers)T2	medium	deterministic

Languageslanguages1

Claim history for Languages
Value	Valid from → to	Status	Source	Confidence	Extractor
en	11 Sept 2026 21:26 UTC → current	current	Hugging Face Hub (public pages, model cards, papers)T2	medium	deterministic

Base modelbase_model1

Claim history for Base model
Value	Valid from → to	Status	Source	Confidence	Extractor
stepfun-ai/Step-3.5-Flash	11 Sept 2026 21:26 UTC → current	current	Hugging Face Hub (public pages, model cards, papers)T2	medium	deterministic

File sizefile_size_gb1

Claim history for File size
Value	Valid from → to	Status	Source	Confidence	Extractor
241.9 GB	11 Sept 2026 21:26 UTC → current	current	Hugging Face Hub (public pages, model cards, papers)T2	medium	deterministic

Hugging Face repohf_repo1

Claim history for Hugging Face repo
Value	Valid from → to	Status	Source	Confidence	Extractor
cerebras/Step-3.5-Flash-REAP-121B-A11B	11 Sept 2026 21:10 UTC → current	current	Hugging Face Hub (public pages, model cards, papers)T2	medium	deterministic

Pipeline tagpipeline_tag1

Claim history for Pipeline tag
Value	Valid from → to	Status	Source	Confidence	Extractor
text-generation	11 Sept 2026 21:10 UTC → current	current	Hugging Face Hub (public pages, model cards, papers)T2	medium	deterministic

Model cardmodel_card_url1

Claim history for Model card
Value	Valid from → to	Status	Source	Confidence	Extractor
https://huggingface.co/cerebras/Step-3.5-Flash-REAP-121B-A11B	11 Sept 2026 21:10 UTC → current	current	Hugging Face Hub (public pages, model cards, papers)T2	medium	deterministic

Downloadsmetric.downloads1

Claim history for Downloads
Value	Valid from → to	Status	Source	Confidence	Extractor
148	11 Sept 2026 21:10 UTC → current	current	Hugging Face Hub (public pages, model cards, papers)T2	medium	deterministic

Likesmetric.likes1

Claim history for Likes
Value	Valid from → to	Status	Source	Confidence	Extractor
15	11 Sept 2026 21:10 UTC → current	current	Hugging Face Hub (public pages, model cards, papers)T2	medium	deterministic

Gatedgated1

Claim history for Gated
Value	Valid from → to	Status	Source	Confidence	Extractor
No	11 Sept 2026 21:26 UTC → current	current	Hugging Face Hub (public pages, model cards, papers)T2	medium	deterministic

Last modifiedlast_modified1

Claim history for Last modified
Value	Valid from → to	Status	Source	Confidence	Extractor
2026-02-25T07:13:23+00:00	11 Sept 2026 21:10 UTC → current	current	Hugging Face Hub (public pages, model cards, papers)T2	medium	deterministic

Library namelibrary_name1

Claim history for Library name
Value	Valid from → to	Status	Source	Confidence	Extractor
transformers	11 Sept 2026 21:26 UTC → current	current	Hugging Face Hub (public pages, model cards, papers)T2	medium	deterministic

Downloads all timemetric.downloads_all_time1

Claim history for Downloads all time
Value	Valid from → to	Status	Source	Confidence	Extractor
943	11 Sept 2026 21:26 UTC → current	current	Hugging Face Hub (public pages, model cards, papers)T2	medium	deterministic

Model typemodel_type1

Claim history for Model type
Value	Valid from → to	Status	Source	Confidence	Extractor
step3p5	11 Sept 2026 21:26 UTC → current	current	Hugging Face Hub (public pages, model cards, papers)T2	medium	deterministic

Tagstags1

Claim history for Tags
Value	Valid from → to	Status	Source	Confidence	Extractor
transformers, safetensors, step3p5, text-generation, stepfun, MOE, pruning, compression, custom_code, en	11 Sept 2026 21:26 UTC → current	current	Hugging Face Hub (public pages, model cards, papers)T2	medium	deterministic

Weights dtypeweights_dtype1

Claim history for Weights dtype
Value	Valid from → to	Status	Source	Confidence	Extractor
BF16, F32	11 Sept 2026 21:26 UTC → current	current	Hugging Face Hub (public pages, model cards, papers)T2	medium	deterministic

Claims are temporal and append-only: a new observation closes the previous claim (valid_to) instead of overwriting it. Conflicting claims from different sources are kept side by side and flagged — never averaged. Methodology →

Provenance

Attributed facts

21

Source tiers

T221

Freshest observation

10 h ago

Conflicts

None

Source documents 3

Source documents
Source	Document	Type	Tier	Last observed	Snapshots
Hugging Face Hub (public pages, model cards, papers)	huggingface.co/cerebras/Step-3.5-Flash-REAP-121B-A11B	model_page	T2· Quality secondary	10 h ago	3
Hugging Face Hub (public pages, model cards, papers)	huggingface.co/models?author=cerebras&p=0&sort=downloads	listing	T2· Quality secondary	10 h ago	3
Hugging Face Hub (public pages, model cards, papers)	huggingface.co/cerebras/Step-3.5-Flash-REAP-121B-A11B/raw/main/README.md	model_card	T2· Quality secondary	11 h ago	1

Tier 1 = official/primary, 2 = quality secondary, 3 = community, 4 = unverified. Every snapshot is archived; see all sources and the methodology.

Data quality (53/100) measures how well AI Atlas knows this entity — completeness, primary-source ratio, freshness, conflicts — never how good the model is. Methodology →