Headless Thrones

StepFun · Official-source model record

Step-5-Preview

Step · Version Step-5-Preview

PreviewChecked Oct 23, 2026
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Publisher-sourced inventory. Specifications come from official documentation and model cards. “Not documented” means we have no verified value. This inventory is separate from our editorial reviews.

Coverage & sources ↗

Current catalog answers

What to know about Step-5-Preview

AI-compiled from linked model documentation. This is a catalog reference, not an independent performance review. Catalog checked October 23, 2026.

Which Step-5-Preview does this page describe?

Step-5-Preview is a model record from StepFun in the Step family. Source

The recorded model identifier or checkpoint is Step-5-Preview. Use that exact identifier when checking documentation or a provider listing. Source

How can you access Step-5-Preview?

The catalog documents API and Open weights access for Step-5-Preview. Source 1 · Source 2

As of the catalog check, this version was listed as a preview. Source

For API use, confirm the exact model identifier, your account and region, and the endpoint's current limits in the linked documentation. An API listing does not establish access through a consumer subscription.

Open weights means the model weights are distributed for use under their stated terms. It does not establish a hosted API, an open-source license, or a hardware requirement. This record documents API access separately.

What are Step-5-Preview's context and output limits?

The documented context window is 1,000,000 tokens. Source

A separate maximum-output value is not established in this record. The context or input figure should not be used as an output allowance.

Context, input and output limits describe different constraints. Do not add the figures together to infer a larger window. Check the endpoint's accounting for conversation history, system instructions, tools, media and generated tokens; a documented maximum is not a guarantee of answer quality or a measured usable capacity.

What can Step-5-Preview receive and generate?

Documented inputs: text, image, and video. Source

Documented outputs: text. Source

Input support and output generation are separate capabilities. Reading an image does not establish image generation; a text output listing does not establish speech output. File sizes, formats and media limits depend on the documented implementation.

What license is recorded for Step-5-Preview?

The recorded license label is Custom license (see official model card). Source

Read the linked license and associated use terms for this exact version before redistribution, commercial deployment or fine-tuning. A label alone does not establish every permission, restriction or obligation, and it does not determine the terms of a separate hosted service.

What is documented about the Step-5-Preview checkpoint?

This evidence refers to stepfun-ai/Step-5-Preview at recorded revision 364b3b03fed2477aa0953fe855a2c4c8c48ee3cc, checked October 23, 2026. Repository metadata

Safetensors metadata records 604,339,504,832 stored parameters. This is a stored-weight count, not necessarily the number activated per token, a download size or a GPU-memory requirement. Repository metadata

Recorded architecture class: Step5ForConditionalGeneration. Repository metadata

Repository access gate: false. This records the repository's gate setting when checked; licensing and use terms still apply. Repository metadata

What the configuration file says

The pinned config.json section text_config contains these values. Pinned configuration

max_position_embeddings
1,048,576
rope_scaling
{"rope_type":"llama3","factor":1,"original_max_position_embeddings":1048576,"low_freq_factor":1,"high_freq_factor":32}
sliding_window
512
torch_dtype
bfloat16
num_attention_heads
64
num_hidden_layers
92
hidden_size
4,096

Configuration values describe the checkpoint and its implementation. In particular, max_position_embeddings, sliding_window and rope_scaling do not independently establish an API context limit, tested usable length or hardware requirement. Runtime, quantization, cache, batch size and input length affect deployment behavior.

Read the retrieved model card for setup and qualifications. Model card

Keep the exact version in view

Other Step models from StepFun.

These are separate records in the same publisher family. A shared family name does not establish equal capabilities or interchangeable licenses.

Step-3.5-Flash

API · Open weights · 256,000 context tokens

Step-3.7-Flash

API · Open weights · 256,000 context tokens

The documented record

Specifications, with their sources.

A missing value remains unknown. Input limits, output limits and the total context window are separate measurements.

Publisher
StepFunSource ↗
Family
StepSource ↗
Version
Step-5-PreviewSource ↗
Availability
PreviewSource ↗
Access
API · Open weightsSource 1 ↗Source 2 ↗
Inputs
Text · Image · VideoSource ↗
Outputs
TextSource ↗
Context window
1,000,000 tokensSource ↗
Maximum input
Not documented
Maximum output
Not documented
Knowledge cutoff
Not documented
Training-data cutoff
Not documented
Training completed
Not documented
Release date
Not documented
License
Custom license (see official model card)Source ↗
Input price / 1M tokens
Not documented
Output price / 1M tokens
Not documented

Read this with the numbers.

Official publisher weight listing; availability refers to this distribution, not a guaranteed hosted API. Base, SFT and research variants are identified by their exact published names. Official quantization/runtime variants are retained as aliases. Official context K/M display values normalized as decimal tokens. Publisher repository evidence (2026-10-23): Published architecture metadata: Step5ForConditionalGeneration. Published safetensors metadata counts 604,339,504,832 stored parameters; this is not an active-parameter count for mixture-of-experts models. Published text_config configuration: max_position_embeddings=1048576; sliding_window=512; dtype=bfloat16; 92 hidden layers. The configuration includes explicit RoPE scaling ({"rope_type":"llama3","factor":1,"original_max_position_embeddings":1048576,"low_freq_factor":1,"high_freq_factor":32}); no effective context extension is inferred. Checkpoint configuration is not a verified hosted serving limit; context and output limits remain separate documented fields.

Model identifiers and aliases 4
  • step-5-preview
  • stepfun-ai/Step-5-Preview
  • stepfun-ai/Step-5-Preview-BF16
  • stepfun-ai/Step-5-Preview-NVFP4

Follow the evidence

Official sources.

  1. Step-5-Preview official model card ↗huggingface.co
  2. list — official StepFun documentation ↗platform.stepfun.com
  3. Step-5-Preview: official publisher repository metadata ↗huggingface.co
  4. Step-5-Preview: publisher model card at revision 364b3b03fed2 ↗huggingface.co
  5. Step-5-Preview: published checkpoint configuration at revision 364b3b03fed2 ↗huggingface.co

From the Headless Thrones newsroom

Editorial about Step-5-Preview

No published articles are linked to this exact model yet. New coverage will appear here as it is published.

Your starting point

Step-5-Preview

StepFun · API / Open weights

Browse all models ↗
Inputs
Text · Image · VideoSource ↗
Outputs
TextSource ↗
Context window
1,000,000 tokensSource ↗
Knowledge cutoff
Not documented

A place to begin comparing

45 models to consider.

Matches must share an access route, support every documented input type of your starting model, and return text. When both publish a context limit in the same field, the candidate must fall between half and twice that limit. Unknown or differently defined limits remain as broader matches, after verified near-context matches. Within each group, recent documented releases appear first. These criteria do not establish equal quality. The full current inventory is considered.

MiniMax

MiniMax-M3.1-Flash

Text + Image + Video input; text output · Shared access: API / Open weights · Documented context within ½–2×

Xiaomi

mimo-v2.6-flash

Text + Image + Video input; text output · Shared access: API · Documented context within ½–2×

Xiaomi

mimo-v2.6-pro

Text + Image + Video input; text output · Shared access: API · Documented context within ½–2×

MiniMax

MiniMax-M3

Text + Image + Video input; text output · Shared access: API / Open weights · Documented context within ½–2×

Amazon

Nova 2 Lite

Text + Image + Video input; text output · Shared access: API · Documented context within ½–2×

Amazon

Nova Premier

Text + Image + Video input; text output · Shared access: API · Documented context within ½–2×

Google

Gemini 4 Argon

Text + Image + Video input; text output · Shared access: API · Documented context within ½–2×

Meta

Muse Spark 1.1

Text + Image + Video input; text output · Shared access: API · Documented context within ½–2×

Meta

Muse Spark 1.2

Text + Image + Video input; text output · Shared access: API · Documented context within ½–2×

Meta

Muse Spark 1.2 Contributor

Text + Image + Video input; text output · Shared access: API · Documented context within ½–2×

Meta

Muse Spark 1.3

Text + Image + Video input; text output · Shared access: API · Documented context within ½–2×

Meta

Muse Spark 1.3 Contributor

Text + Image + Video input; text output · Shared access: API · Documented context within ½–2×

A record you can follow

The source belongs beside the fact.

Official sources

Model records cite the developer’s documentation, release notes and model cards. A listing alone is not a tested service or a recommendation.

Dates mean different things

Knowledge cutoff, training-data cutoff, training completion and release date are separate fields. A model’s name or repository upload date does not establish any of them.

Limits need context

Some publishers use rounded K/M token figures. Deployment, reasoning settings and regional access can change usable limits. Read the source before choosing.

Coverage and last check

Independent editorial model library assembled from primary vendor documentation and official publisher model cards. This is a dated, auditable inventory of the sources reviewed, not a claim to every model worldwide. First-party language-model inventory for OpenAI, Anthropic, Google Gemini/Gemma, xAI, Meta and Reflection. Includes vendor-listed legacy/retired identities with explicit statuses; official pretrained and instruction-tuned checkpoints remain distinct. Excludes embeddings, moderation/guard models, image/audio/video-only generation, community fine-tunes, speculative draft helpers, format/runtime/quantization duplicates, and PaliGemma dataset-specific benchmark fine-tunes. Availability means documented vendor API or downloadable official weights, not guaranteed account eligibility. Unknown specifications and dates remain null. Rounded K/M limits preserve vendor granularity; exact integers are used only where documented. No OpenRouter facts are used. Primary-source inventory of language-capable models from Alibaba/Qwen, DeepSeek, Moonshot, MiniMax, Z.ai, ByteDance Seed, Tencent, Baidu, Xiaomi, StepFun, 01.AI, Shanghai AI Laboratory, Baichuan and OpenBMB. Includes full reachable official public weight inventories plus documented hosted API models and explicit retirements. Embeddings, reward/classifier/router/tokenizer/draft-head components, standalone OCR/document converters and image/video/audio-only generators are excluded; multimodal language models retained. Official packaging variants are folded into aliases where a canonical listing was identifiable; remaining research/base/SFT variants retain exact identities. Not a guarantee every historical/private/regional model is available. Unknown specifications remain null; K/M API display quantities use decimal normalization where explicitly noted, rather than implying verified exact serving ceilings. Model-name dates and repository creation timestamps are never used as release/training dates. Open weights does not mean unrestricted or OSI-open-source licensing. Some model-card bodies were unreachable; their public inventory metadata is retained and disclosed. Official Mistral, Cohere, AI21, NVIDIA Nemotron, Microsoft Phi/MAI, Amazon Nova, IBM Granite, AllenAI OLMo/Molmo, TII Falcon, Nous Research, Arcee and Essential AI model inventory checked 2026-10-23. Includes base, instruction, reasoning, coding and text-producing multimodal models, including legacy API versions. Excludes embeddings/rerankers/reward and safety classifiers, image/audio/video-only generation, robotics-only models, duplicate quantization/runtime packages, adapters, intermediate checkpoint experiments, and third-party mirrors. Arcee coverage focuses on its named product families rather than exploratory merge repositories. Repository listing means listed, not independently verified API availability. K/M figures are nominal decimal normalizations when the source supplies shorthand; deployment-specific exact token limits may differ. Unverified values remain null. This is a source-backed inventory, not a complete claim-level independent editorial review. Supplemental official Liquid AI, Reka and Inception generative language catalog. Excludes media-only generators and decision/classification-only models. No assumed training dates.

Catalog edition updated . Source links are provided on each model record.

View the full coverage report and discovery sources ↗