Claim · 2026-09-20 · announcement · Stated in source · Supported

StepFun's newsroom post dated 20 September 2026 announced Step 5 Preview as its new flagship model, said it was available in full from that day, and said the model weights would be released on 15 October.

One recorded claim. The claim panel gives its qualification, the source passages with their place in each source, and how it was checked.

What it connects

StepFun / 阶跃星辰 → published → 阶跃发布旗舰模型 Step 5 Preview (StepFun newsroom post, 20 September 2026)

Where it appears

No collection page holds this claim. It is listed with its records in the explorer.

Claim and evidence

StepFun / 阶跃星辰published ↓阶跃发布旗舰模型 Step 5 Preview (StepFun newsroom post, 20 September 2026)

Machine-checked, not reviewed by an editorStated in sourceSupported

Supporting evidence: primary · 1 source

Date: 2026-09-20 · announcement Records dated 2026 →

Scope and limitsThe release of weights on 15 October is a plan stated in this post, recorded as announced; whether and when weights became available is a separate matter (the Hugging Face repository shows weight files from 20 September 2026, but its visibility at that date is not known). 开源 is rendered "open source" as the post's own term. Performance claims in the post are out of scope.

The evidence 02

primary sourceSupports the claim

阶跃星辰官网（构建文件 index-4zBpLKmx.js）

StepFun (阶跃星辰), stepfun.com · Publication date unknown · In Simplified Chinese (zh-Hans)

Cite the original source

Cite the original document, not Selekoa. Check these details against it.

Source excerpt

“阶跃发布旗舰模型 Step 5 Preview”

Location in source Newsroom post dated 2026-09-20, title

How it was read Retrieved directly from the publisher

Machine-checked · 2026-10-31

Source details and check notes

Authors: StepFun
Version: Undated page, retrieved on 2026-10-29 (SHA-256 4a9822256a9c02a015133c2dbf8edd147c117d9c13e633cdd6c50258ae484ae5) directly from the publisher. Version: index-4zBpLKmx.js. The stepfun.com pages are served as an empty JavaScript shell; their text (newsroom posts with their dates, and the footer) is carried in this content-hashed build file, read as it stood on 29 October 2026. The file name changes with each site build; earlier builds not inspected. Its wording can change; earlier wording is not authenticated. English title (machine translation): “StepFun website build file carrying the newsroom posts and site footer”.
Canonical address: Open the canonical source ↗
Accessed: 2026-10-29
Language: Simplified Chinese (zh-Hans)
Attribution: StepFun, “阶跃星辰官网（构建文件 index-4zBpLKmx.js）”.
Reuse: No open redistribution licence asserted. Bibliographic metadata, editorial paraphrases and short attributed quotations (at most 50 words each). Recheck terms before wider redistribution.
Check notes: Candidate pack passage, Chinese frontier-AI institutions, third collection (research/china-labs-3). The quotation (11 words, each CJK character counted as one) matched the text retrieved for the candidate pack on 2026-10-29 and again in a fresh retrieval the same day, read directly from the publisher. Matching ignored differences of whitespace, case, quotation marks, dashes and Unicode compatibility forms, so the source’s typography can differ. English machine translation, not verified by a person: “StepFun releases flagship model Step 5 Preview”. A cross-family machine check (2026-10-31, item K117) answered the record’s question blind from fresh retrievals and agreed with the record. No human editorial review.

primary sourceSupports the claim

阶跃星辰官网（构建文件 index-4zBpLKmx.js）

StepFun (阶跃星辰), stepfun.com · Publication date unknown · In Simplified Chinese (zh-Hans)

Cite the original source

Cite the original document, not Selekoa. Check these details against it.

Source excerpt

“Step 5 Preview 依旧是一款…我们将在10 月 15 日释放模型权重”

Location in source Newsroom post dated 2026-09-20, closing paragraph

How it was read Retrieved directly from the publisher

Machine-checked · 2026-10-31

Source details and check notes

Authors: StepFun
Version: Undated page, retrieved on 2026-10-29 (SHA-256 4a9822256a9c02a015133c2dbf8edd147c117d9c13e633cdd6c50258ae484ae5) directly from the publisher. Version: index-4zBpLKmx.js. The stepfun.com pages are served as an empty JavaScript shell; their text (newsroom posts with their dates, and the footer) is carried in this content-hashed build file, read as it stood on 29 October 2026. The file name changes with each site build; earlier builds not inspected. Its wording can change; earlier wording is not authenticated. English title (machine translation): “StepFun website build file carrying the newsroom posts and site footer”.
Canonical address: Open the canonical source ↗
Accessed: 2026-10-29
Language: Simplified Chinese (zh-Hans)
Attribution: StepFun, “阶跃星辰官网（构建文件 index-4zBpLKmx.js）”.
Reuse: No open redistribution licence asserted. Bibliographic metadata, editorial paraphrases and short attributed quotations (at most 50 words each). Recheck terms before wider redistribution.
Check notes: Candidate pack passage, Chinese frontier-AI institutions, third collection (research/china-labs-3). The quotation (22 words, each CJK character counted as one) matched the text retrieved for the candidate pack on 2026-10-29 and again in a fresh retrieval the same day, read directly from the publisher. Matching ignored differences of whitespace, case, quotation marks, dashes and Unicode compatibility forms, so the source’s typography can differ. Elided quotation: the ellipses mark omitted words, so the passage is not continuous in the source. English machine translation, not verified by a person: “Step 5 Preview is still an [open-source model] … we will release the model weights on 15 October”. A cross-family machine check (2026-10-31, item K117) answered the record’s question blind from fresh retrievals and agreed with the record. No human editorial review.

Status and meaning

Editorial status. Not reviewed by an editor. An exploratory record that no editor has accepted. This status does not say whether a person has read any linked passage. Each evidence record above shows how it was checked.

Relation. Publication of a specific document or version. Publication of a policy is not evidence of implementation.

Date. Date shown on the post as read in the site build file on 29 October 2026; the post's original publication time is not separately verified.

Record ID c3-stepfun-step5-announcement