Stealth Model Watch
Context window
1M tokens
Stealth Model Watch · An OpenRouter stealth-model file
Who Made
Ox Alpha?
Answered on Aug 26, 2026: Ox Alpha is Z.AI (Zhipu)'s GLM series. This file keeps the complete seven-day hunt — what was verified, what was inferred, and what it took to get there.
CONFIRMED: Z.AI (Zhipu) · GLM series · Day 41
- Official: GLM-5.3-Flash (320B-A18B)
- 1,048,576-token context
- $0 preview pricing
- Text · image · video input
Community hands-on test (Bijan Bowen, YouTube) — plays here, no need to leave.
Independent tracker — not affiliated with OpenRouter, OpenCode, or any model lab. The identity question is now answered — the evidence archive below shows how we got there.
The model
What Is Ox Alpha?
The verified baseline: everything below comes from OpenRouter's own listing and the platforms' official announcements — no community guesswork in this section.
- Model ID
- stealth/ox-alpha
- Provider
- Z.AI Co. (Zhipu) — announced Aug 26, 2026 as GLM-5.3-Flash (320B-A18B), an open-source GLM-5 model Official announcement ↗
- Released
- August 20, 2026
- Positioning
- Reasoning model for efficient coding, sustained agentic work and production workloads
- Context window
- 1,048,576 tokens
- Max output
- 131,072 tokens
- Input / output
- Text, image and video in · text out
- Tool support
- tools, tool_choice, response_format — JSON output without strict schema enforcement
- Preview price
- $0 per million tokens, in and out
- Early traffic
- ≈336B prompt tokens and ≈4B completion tokens processed within about a day online
- Uptime
- 99.99% across its first three days
- Benchmarks
- Official AA Intelligence Index 57 (level with Claude Opus 4.8). First full third-party run: 58.4% on DeepSWE (113 tasks). See our full audit
- Data terms
- Prompts and completions are retained by the provider but not used for training (Stealth Model Terms)
Source: OpenRouter — stealth/ox-alpha listing ↗ · Figures captured from the listing on Aug 21, 2026.
Current snapshot
What the OpenRouter Listing Says Now
A point-in-time capture of the public listing. These operational details can change during the preview and should not be read as permanent model facts.
Inputs
Text · image · video
Preview price
$0 per million tokens
Provider
Z.AI (Zhipu) — GLM-5.3-Flash, Aug 26
Last checked: · Source: OpenRouter model listing ↗
Evidence
Evidence Timeline: How the Ox Alpha Identity Hunt Unfolded
Newest first — scroll to the bottom for where the story began. Each entry is tiered: verified fact, community inference, or rumor — and linked to its source.
- New Verified fact
The backdrop: Stripe acquires OpenRouter
The stage Ox Alpha dominated was itself in flux: Stripe's acquisition of OpenRouter (announced Aug 19, reported at $7.5B–$8B) had just closed, with Stripe CEO Patrick Collison calling the stealth release 'very impressive.' The biggest launch in OpenRouter's history landed weeks into the new ownership.
- Verified fact
Official: Ox Alpha ships as GLM-5.3-Flash, weights open
Z.AI formally announced and open-sourced GLM-5.3-Flash (320B total, 18B active) — Ox Alpha was its anonymous preview, nicknamed "牛来" in the Chinese community. Official AA Intelligence Index: 57, level with Claude Opus 4.8. Pricing at 1/10 of GLM-5.3 (1/20 in the launch window, 1/40 of Opus 4.8). Weights live at huggingface.co/zai-org/GLM-5.3-Flash, with the entire preview served on domestic Chinese chips.
Z.AI official launch — GLM-5.3-Flash 「正式发布」 (Aug 26, 2026) - Verified fact
Revealed: Z.AI confirms Ox Alpha is GLM
Ending the seven-day mystery, Z.AI Co. (Zhipu) told Bloomberg News that Ox Alpha is a new iteration of its GLM series and said it would release open weights the same night. The company also confirmed the model stays free during the preview. By then Ox Alpha had climbed to #1 on OpenRouter's leaderboard, with usage more than double DeepSeek's.
Bloomberg News · Luz Ding · Aug 26 — via The Edge Malaysia - Verified fact
Mainstream coverage arrives, identity still unresolved
TechCrunch and Bloomberg both cover Ox Alpha as a fast-moving mystery model. Their reporting confirms the model is attracting developer attention, but neither outlet identifies the developer or treats any community theory as confirmed. OpenRouter still describes the provider as anonymous during the preview.
TechCrunch — “Who's behind the new stealth model Ox Alpha?” (Aug 23) - Verified fact
First full-scale benchmark: 58.4% on DeepSWE
An independent developer completes the first end-to-end third-party run — all 113 DeepSWE tasks in 20h 39m under a standard agentic harness. Result: 66/113 solved, 58.4% (95% CI [49.2%, 67.1%]), level with Claude Opus 4.8 at 59%. The rumored ~80% pass rate from the 10-task comparison is dead. The score also understates reasoning: 80% of tasks land ≥90% of their fail-to-pass tests, and 9.7% of the suite is lost to repeated tool-call format failures rather than failed logic. Ox Alpha has not yet been added to the official leaderboard.
The public benchmark repo (GitHub) — MatchaOnMuffins/oxalpha The rumor 80% · ~80% · 10-task sample, debunkedOx Alpha — measured 58.4% · CI [49.2%, 67.1%]Claude Opus 4.8 59% · referenceShare of the 113 DeepSWE tasks fully solved · full DeepSWE audit
- Rumor
Rumor posts fill the vacuum
The "mia" persona (@MiaAI_lab) vagueposts having private confirmation that Ox Alpha is "NOT what you think it is," claims it will be open-weight and run on 2× DGX Sparks — unverified. Others speculate an unreleased multimodal GLM-5.3 build after reports of outputs identical to public GLM-5.3.
- Community inference
Community evals: strong but small-sample
An X user's 10-task comparison puts Ox Alpha first at 80% — ahead of Fable 5 (65%), GLM-5.3 (62%), Grok-4.6 (62%) and GPT-5.6 Sol (52%). Ten questions, not a benchmark. Hands-on reports praise creative output while flagging weak visual reasoning; pelican-on-a-bicycle SVG tests at low/high/max reasoning effort circulate, with an over-thinking tendency reported at max.
- Community inference
Counter-fingerprints keep the race open
Other testers report edge-case tokenizer glitches that match MiMo 2.5 Pro behavior rather than GLM 5.2/5.3, and argue only a hyperscaler could serve 100T free tokens a day. Hacker News commenters add stylometry of thinking traces ("almost certainly a GLM model") and mixed censorship-probe results.
- Community inference
Tokenizer fingerprinting converges on GLM
Community forensics run adversarial strings against Ox Alpha: one agent-assisted test matches the GLM tokenizer on 13/13 CJK, emoji and Cyrillic strings; a 25-prompt sweep lines token counts up with GLM-5.3 within a constant ~75-token wrapper; video-token math also lines up with GLM. An error-message fingerprint ([1210] "This model always engages in thinking…") matches Z.ai's GLM-5.3 API verbatim.
- Verified fact
Real production traffic arrives
OpenRouter activity shows ≈336B prompt tokens and ≈4B completion tokens processed within about a day. Top senders: Claude Code (61.8B tokens), Hermes Agent (56.1B), Oh-My-Pi (49.9B), DeepSeek Harness (44.2B), ZCode (30.3B). Uptime holds at 99.99% over three days.
- Verified fact
OpenCode declares a free week
OpenCode makes Ox Alpha free for one week at "near unlimited usage," claiming capacity for 100 trillion tokens a day and a zero-retention provider policy. Its Zen docs list the model as "Ox Alpha Free" with the id x-preview-f-free.
- Verified fact
Anonymous launch on OpenRouter
Ox Alpha goes live under stealth/ox-alpha with no developer attribution. OpenRouter introduces "a frontier model built for efficient coding, sustained agentic work, and real-world production use," suited to long-horizon software engineering and workflows that mix text with visual context.
OpenRouter — stealth/ox-alpha model listing (captured Aug 21, 2026)
Community items are dated approximately from post timestamps; launch-day items are dated by the official announcements themselves.
Forensics
Tokenizer Fingerprint: Ox Alpha vs GLM-5.3
Tokenizer fingerprinting is the core identity evidence so far. A tokenizer splits text into tokens deterministically, and each lab's tokenizer leaves a different count behind — counts that cannot be changed by prompt engineering. If Ox Alpha shares a tokenizer with a public model, every probe string should agree with it.
Adversarial string battery — 13/13 match
An agent-assisted test feeds 13 deliberately weird strings (CJK, emoji, Cyrillic) through the API: token counts come back identical to the GLM tokenizer published on Hugging Face, 13 out of 13.
Source: r/opencode identity thread ↗25-prompt sweep with a constant offset
A developer known as dax (on X) compares raw token counts across 25 different prompts: Ox Alpha tracks GLM-5.3 each time, off by a constant ~75-token wrapper — consistent with the same base tokenizer under a different serving template.
Source: OfficeChai report ↗Error-message fingerprint
Sending reasoning_effort:"none" gets rejected with [1210] "This model always engages in thinking…" — the same numeric code and wording as Z.ai's GLM-5.3 API error.
Source: r/opencode identity thread ↗Backend-language tell
A malformed image triggers a Chinese-language server error (图片输入格式/解析错误, "image parse error"), pointing at a Chinese-origin serving stack — though a proxy layer can't be fully ruled out.
Source: r/opencode identity thread ↗Shared dirty-token stumble
Ox Alpha reportedly trips on the same "dirty token" edge case that has previously caught Qwen- and GLM-family models — weak alone, but consistent with the family match above.
Source: OfficeChai report ↗Video-token math
Community analysis of how video input is chunked into tokens also lines up with GLM's approach, notable because Ox Alpha is the first anonymous release to advertise video input at all.
Source: r/opencode launch thread ↗Bottom line: the strongest public evidence tied Ox Alpha to the GLM tokenizer family — and the community's read was right. On Aug 26, 2026, Z.AI officially announced Ox Alpha as GLM-5.3-Flash; the full evidence chain lives on in our confirmation page.
Speculation
The Four Theories — and the Answer
The four candidates the community kept returning to, each with its supporting evidence and open doubts. On Aug 26, Z.AI ended the debate.
01
Xiaomi MiMo V3
Ruled out — fingerprint mismatch
The playbook repeat offender: Xiaomi has run anonymous previews before, and Ox Alpha's spec sheet fits the MiMo line. After the Aug 26 confirmation, this theory is closed.
Supporting
- Precedent: Hunter Alpha, an anonymous March 2026 OpenRouter model, was confirmed by Xiaomi as an early internal build of MiMo-V2-Pro (Reuters).
- Launch window sits right at Xiaomi's Q2 FY2026 earnings call; community commenters note executives teased an imminent model release.
- Spec shape matches MiMo's direction — million-token context, native multimodality, agentic coding focus.
- Some edge-case tokenizer glitches reportedly match MiMo 2.5 Pro behavior rather than GLM.
- Commenters read the 100T-tokens-a-day framing as echoing MiMo's earlier capacity collaborations.
Doubts
- The headline tokenizer batteries match GLM, not MiMo.
- MiMo V3 itself is unannounced — nothing official links it to Ox Alpha.
02
Tencent Hunyuan HY4
Ruled out — no scale fit
Only a hyperscaler can give away 100T tokens a day — and Tencent operates exactly that class of inference infrastructure. After the Aug 26 confirmation, this theory is closed.
Supporting
- The original identity thread argues HY4 is the only new model that could be served at this scale.
- Tencent is reportedly testing HY4, according to community observers tracking Chinese releases.
- Free-at-scale distribution requires hyperscale GPU capacity that very few labs possess.
Doubts
- Hy3 just launched and already burned through free OpenRouter compute — an immediate stealth follow-up would be odd.
- No confirmation from Tencent or OpenRouter; "Ox Alpha" doesn't match Hunyuan's HY naming pattern.
03
Google Gemini
Ruled out — no fingerprint
Million-token context plus native video input reads like the Gemini lineage's signature spec sheet. After the Aug 26 confirmation, this theory is closed.
Supporting
- The 1,048,576-token context window matches Gemini's million-token signature.
- Native video input is rare among frontier APIs and standard for Gemini — "only one frontier lab bakes multimodality into its base models," as one commenter put it.
Doubts
- Chat self-identification ("I am Gemini") proves nothing — system prompts can make any model say anything.
- No tokenizer fingerprint ties Ox Alpha to Google.
04
Zhipu / Z.ai GLM-5.3 variant
Confirmed
✅ CONFIRMED by Z.AI
Confirmed on Aug 26, 2026: every hard forensic signal — tokenizer, error codes, backend language — pointed here, and Z.AI itself settled it.
Supporting
- Best tokenizer match across multiple independent tests: 13/13 adversarial strings, plus a 25-prompt sweep aligned within a constant wrapper offset.
- The [1210] reasoning_effort rejection matches Z.ai's GLM-5.3 API verbatim; backend errors return in Chinese.
- Precedent: Pony Alpha was revealed as Zhipu's GLM-5 roughly five days after its anonymous debut.
- Z.ai has publicly pushed GLM toward vision and multimodal capability — an unreleased variant would fit that roadmap.
Doubts
- Community skeptics argue Z.ai is compute-strained and couldn't serve 100T free tokens a day.
- GLM-5.3 went public days earlier — the motive to disguise a variant is unclear.
- Minority fingerprint evidence points to MiMo behavior instead.
Update (Aug 26, 2026): Z.AI confirmed Ox Alpha is a new iteration of its GLM series. The community's top-ranked theory was right.
Access
Where to Use Ox Alpha
Manually verified access points as of Aug 21, 2026 — each one checked against its official docs or listing before being included.
OpenRouter
VerifiedHome of the stealth listing. Chat in the playground or call the OpenAI-compatible API under stealth/ox-alpha — $0 during the preview, with tools, structured output and video input supported.
openrouter.ai/stealth/ox-alphaOpenCode Zen
VerifiedOpenCode's curated gateway lists "Ox Alpha Free" (model id x-preview-f-free) with a zero-retention provider policy — free for a limited time at near-unlimited rate limits during the promo week.
opencode.ai/docs/zenHermes Agent · Nous Research
VerifiedNous Research's self-improving agent offers Ox Alpha through its OpenCode and OpenRouter providers; Nous Portal lists it at $0.00/1M tokens, and Hermes Agent ranks #2 among apps sending Ox Alpha traffic on OpenRouter.
portal.nousresearch.comA fourth candidate, Cola, was checked and omitted: no official page or announcement verifying Ox Alpha support could be found at publish time. Platforms are added only after manual verification.
Signals
Community Signals: Follow the Ox Alpha Identity Hunt
The primary threads driving the speculation — linked, not endorsed.
X / Twitter 10-task head-to-head: Ox Alpha 80% @himustafatokmak pits Ox Alpha against Fable 5, GLM-5.3, GPT-5.6 Sol and Grok-4.6 across 10 tasks. Small sample — superseded by the 113-task DeepSWE run below. Reference only. Independent benchmark DeepSWE full run: 58.4% (113 tasks) @henryzhangumich runs every DeepSWE task against Ox Alpha in a 20-hour sweep — debunking the 80% rumor and landing level with Claude Opus 4.8. The most rigorous public data point so far. Reddit · r/opencode "Identity of the OX Alpha model: Hy4" The thread that framed the scale argument for Tencent — and drew the tokenizer counter-evidence for MiMo and GLM. Reddit · r/opencode "Guess what? Another one free model – Ox Alpha" First-hand notes: "Tokenizer and video token math both line up with GLM. Community fingerprinting, so grain of salt." Hacker News Ox Alpha discussion Censorship probes, stylometry of thinking traces, the data-retention debate, and hands-on impressions of the model. Reddit · r/singularity "A stealth model called Ox-Alpha has been released" Wider community reaction to the launch and the 10-question coding comparison against Fable. News OfficeChai: free for a week on OpenRouter and OpenCode Straight news write-up covering the dax tokenizer sweep and the shifting US-vs-China token share on OpenRouter. Analysis OrcaRouter: who's behind the free mystery frontier model? The anonymous-model playbook in full: all four predecessors resolved to Chinese labs within days to weeks.
Community posts are unverified speculation unless the underlying claim comes from OpenRouter or the platforms themselves. We link, we don't endorse.
Reveal watch
Revealed on Day 7: How the Ox Alpha Mystery Ended
No leak, no official countdown — just the track record of four earlier anonymous releases, and a community that read the fingerprints right. Here's where the watch stands now.
Days since release
41
Identity: CONFIRMED
Computed at build time from the Aug 20, 2026 launch date.
How long the predecessors took
- Pony Alpha (Feb 2026) → GLM-5 · Zhipu AI ~5 days
- Hunter Alpha (Mar 11, 2026) → MiMo-V2-Pro · Xiaomi ~8 days
- Elephant Alpha (Apr 2026) → Lingxi Ling-2.6-flash · Ant Group ~2 weeks
- Owl Alpha (late Apr 2026) → LongCat-2.0 · Meituan ~9 weeks
What to watch
- Post-preview pricing replaces $0 (community rumors point to aggressive pricing, unconfirmed).
- The OpenRouter listing switches from an anonymous provider to Z.AI.
- Independent benchmarks re-run on the open weights, separate from the preview endpoint.
- Major labs and aggregators add the model under its real name to their plan rosters.
Update (Aug 26): Z.AI stepped forward on Day 7 and open-sourced the weights as GLM-5.3-Flash — see our confirmation page for the full story. What to watch next: post-preview pricing, and OpenRouter's listing switching from anonymous to a named developer.
FAQ
Ox Alpha FAQ: Tokenizer, Identity & Free Access
Short answers, strictly limited to the verified facts on this page. Guesses are marked unconfirmed.
Who made Ox Alpha?
Z.AI Co. (Zhipu). On August 26, 2026, Z.AI told Bloomberg News that Ox Alpha is a new iteration of its GLM series — confirming what tokenizer fingerprinting had pointed to all along. The full story is on our confirmation page.
Is Ox Alpha free?
Yes — during the preview it is $0 per million tokens in and out on OpenRouter, and Z.AI has confirmed it stays free. Z.AI also announced it will release open weights, so self-hosting may soon be an option; post-preview API pricing has not been announced.
What is the Ox Alpha tokenizer evidence?
Community fingerprinting found Ox Alpha's token counts match the GLM tokenizer family most closely: 13/13 on an adversarial CJK/emoji/Cyrillic string battery, and a 25-prompt sweep aligning with GLM-5.3 within a constant ~75-token wrapper. Counter-tests report some MiMo-like glitches instead. Circumstantial — unconfirmed.
Will the identity be revealed?
It was. On Day 7 (August 26, 2026), Z.AI confirmed to Bloomberg that Ox Alpha is its GLM-series model — faster than three of the four previous stealth models took to be claimed. See the reveal timeline for how the seven-day hunt unfolded.
What is Ox Alpha's benchmark score?
The first full independent benchmark — all 113 DeepSWE software-engineering tasks, run end to end in August 2026 — scored Ox Alpha at 58.4% (66/113), level with Claude Opus 4.8 at 59%. The rumored ~80% pass rate from a 10-task comparison was debunked by that run. Notably, 9.7% of the suite was lost to tool-call formatting failures rather than reasoning.
What is the "DGX Sparks" rumor about Ox Alpha?
An X persona (@MiaAI_lab) vagueposted having private confirmation that Ox Alpha is "NOT what you think it is," claiming it will be released as open weights running on 2× NVIDIA DGX Sparks boxes. It remains completely unverified — no lab has confirmed anything, and the claim predates the 58.4% DeepSWE measurement.
Is Ox Alpha on Hugging Face?
Yes — on Aug 26, 2026 Z.AI open-sourced it as GLM-5.3-Flash (320B-A18B) at huggingface.co/zai-org/GLM-5.3-Flash. Ox Alpha was the anonymous preview name; the open weights carry the official model name.