Originally published on BeatAPI. Facts in the source article were checked on September 27, 2026. OpenRouter still listed Space Bunny Alpha as an anonymous, free preview on September 28.
TL;DR
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What it is: an anonymous "stealth" AI model. OpenRouter lists it as Space Bunny Alpha (
stealth/space-bunny-alpha) and OpenCode as Space Bunny Free (space-bunny-free). Both listings went live on September 23, 2026. - Verified specs: a 1M-token context window, up to 524,288 output tokens, text, image, and video input with text output, mandatory reasoning with five effort levels, tool calling, and $0 pricing during the preview.
- Who built it: officially, nobody has said. Two independent tokenizer studies put it in the MiniMax family. That's strong evidence for the family, not for a specific model version.
- The M3.1 question: MiniMax announced M3.1-Flash-Preview inside its MiniMax Code product on September 27 but hasn't connected it to Space Bunny. "Space Bunny is M3.1" is still speculation.
- Want test results instead of background? Our Hugging Face companion post, "Space Bunny Tested: Real Cases and How to Evaluate a Stealth Model," collects the public test cases and a reusable evaluation plan.
The short answer
Space Bunny is a preview model released under a codename. The developer runs it, gateways route traffic to it, and nobody publicly takes credit until an official launch. OpenRouter states that the model "is developed and operated by a third-party provider who has chosen to remain anonymous during this preview," and that OpenRouter "is not its developer, owner, or provider."
In OpenRouter's launch post on X, the company described it as "a flash model with fast inference, adjustable reasoning, and a 1M-token context window." "Flash" is the important word. This is pitched as a fast, low-cost tier, not a flagship, and community comparisons have treated it that way. It usually gets tested against DeepSeek V4.1 Flash and GLM 5.3 Flash, not the largest frontier models.
Specs and access at a glance
We took these from OpenRouter's public models API, OpenCode's Zen documentation, and the models.dev catalog on September 27, 2026.
| OpenRouter | OpenCode (Zen and Go) | |
|---|---|---|
| Name and ID | Space Bunny Alpha, stealth/space-bunny-alpha | Space Bunny Free, space-bunny-free |
| Listed | Sep 23, 2026, 14:48 UTC | Sep 23, 2026 |
| Context / max output | 1,000,000 / 524,288 tokens | 1,048,576 / 524,288 tokens |
| Modalities | Text, image, video in; text out | Text, image, video in; text out |
| Reasoning | Always on; low, medium, high, xhigh, max; default max | Low through max |
| Price | $0 / $0 per million tokens | Free for a limited time |
| Data terms | Provider may retain prompts and completions; not used for training | Zero retention; no training use |
The model also shows up in Kilo's catalog at no cost. The "tokenizer" field on OpenRouter says "Other," and neither gateway publishes a knowledge cutoff.
Two practical notes:
- The data terms differ by route. If you're testing with company code, OpenCode's zero-retention wording is stricter than OpenRouter's retain-but-don't-train wording. The Chinese developer blog AI Pioneer gave the same advice.
- Reasoning can't be switched off. Hiding the reasoning text doesn't stop the model from spending reasoning tokens. On OpenRouter the default effort is max, which affects both latency and token usage.
Timeline
Times are UTC unless noted.
- Sep 23, 14:48: OpenRouter lists the model at $0. OpenCode lists Space Bunny Free the same day and calls it free for a limited time.
- Sep 23, 15:25: X user cheatyyyy posts that the model's text tokenizer "perfectly matches" MiniMax M3's and that the image tokenizer looks different, possibly upgraded.
- Sep 23, afternoon: YFarmX publishes a 50-string token-count comparison that places Space Bunny inside the MiniMax signature.
- Sep 23, 22:23: A fan domain for the model is registered. More on that site below.
- Sep 24: The developer behind the open-source stealthprint toolkit (GitHub user majiayu000) publishes a multi-layer fingerprint study on OpenCode Go. Chinese outlets, BlockBeats among them, report the community's MiniMax M3.1 theory.
- Sep 26 (UTC+8): AI Pioneer reports that Space Bunny reached the top of OpenRouter's daily ranking, ahead of DeepSeek V4.1 Flash and GLM 5.3 Flash.
- Sep 27 (UTC+8): IT Home reports that MiniMax announced M3.1-Flash-Preview inside MiniMax Code, with no model card or API price. MiniMax hasn't said it is Space Bunny.
Who's behind Space Bunny? The evidence, ranked
Identity claims vary a lot in quality. We sort them by how hard each one would be to fake or misread.
| Evidence | What it shows | Source | Strength |
|---|---|---|---|
| Token counts match MiniMax on 50 of 50 strings; the next-closest family scores 29 | MiniMax tokenizer family | YFarmX | Strong |
| 24 of 24 probes match live MiniMax M3 and M2.5 endpoints on the same gateway; Kimi models differ on 14 of 24 | MiniMax family; argues against Kimi | stealthprint | Strong |
| Accepts inputs of 1M tokens, while MiniMax M2.5's endpoint caps at 204,800 | Newer than the M2.5 generation | stealthprint | Moderate |
| Knows events from November 2025 that M3 doesn't | Possibly fresher training than M3 | stealthprint (labeled medium-confidence inference) | Moderate |
| M3.1 entries with 1M context and low, high, and max effort in MiniMax Code test files | MiniMax is preparing an M3.1 | Reported by BlockBeats and EyesTech | Circumstantial |
| Corrupted-image error text reportedly identical to MiniMax's own "(2013)" error | MiniMax serving stack | Summarized by AI Pioneer; stealthprint found the gateway's errors normalized on its route | Disputed |
| Says "I'm ChatGPT" or "GPT-5, created by OpenAI" | Nothing reliable | YFarmX and stealthprint, both of whom attribute it to the missing identity prompt | Weak |
| Reconstructed prompt resembles OpenAI's Harmony format and uses a "Juice" budget field | Possible OpenAI link | Unofficial fan site | Speculative |
| Moon, rabbit, and Mid-Autumn Festival timing, which suggests Moonshot's Kimi | Name association only | Community chatter | Weak |
| "Space" in the name, so SpaceX or xAI | Meme | Community chatter reported by AI Pioneer | None |
Our read: Space Bunny is very likely a MiniMax-family model, and probably newer than M3. That's a reasonable conclusion from independent tokenizer work. "It is exactly MiniMax M3.1" isn't confirmed. A tokenizer shared across generations can't pin down a checkpoint, and MiniMax's September 27 M3.1-Flash-Preview announcement didn't mention Space Bunny.
Past stealth listings eventually got claimed by their vendors. Siora Labs notes that the previous OpenRouter stealth model, Ox Alpha, was revealed as GLM-5.3-Flash and stopped being free at the reveal. It's reasonable to expect the same for Space Bunny, but that's an expectation, not a fact.
A note on the unofficial fan site
A site named after the model's slug appeared within hours of launch. Domain records show it was registered on September 23 at 22:23 UTC, about seven and a half hours after the OpenRouter listing. It calls itself an "independent field guide," doesn't name its operator, and promotes an unrelated local AI audio app.
It isn't run by OpenRouter, OpenCode, or any model lab. Its most-cited numbers come from its own benchmark subsets: 82.0% on 60 GPQA Diamond questions, 46.1% on 300 Humanity's Last Exam questions, and 7.0 out of 10 on the AI BENCHY suite. They're interesting data points, but they aren't vendor results, and you shouldn't compare them directly with full-benchmark scores.
Should you use it?
It's worth trying for open-source work, prototypes, and long agent sessions while it's free. That's where public reports are most positive. Don't use it for production traffic or sensitive code without checking the route's data terms. There's no model card or official benchmark, and the free window is explicitly temporary. OpenCode's offer was announced as roughly one week, and AI Pioneer read the public records as ending around September 30.
For test cases (Minecraft builds, SVG animations, image-to-app demos, video annotation, long-context retrieval, speed measurements) and a prompt set you can reuse, see our companion post on Hugging Face, "Space Bunny Tested: Real Cases and How to Evaluate a Stealth Model."
Using BeatAPI alongside a stealth preview
BeatAPI doesn't offer Space Bunny. We checked the public model catalog on September 27, 2026. What BeatAPI does offer is the set of named models you'd want to test a stealth model against, all behind one API key:
- MiniMax-M3, the closest confirmed relative, at $0.21 input and $0.84 output per million tokens. MiniMax's official standard price is $0.30 and $1.20 for requests up to 512K input tokens.
- claude-opus-5-5 at $2 input and $10 output per million tokens. Anthropic's official list price is $4 and $20.
- deepseek-v4.1-flash and glm-5.3-flash, the two Flash models Space Bunny is most often compared with in public tests.
The same key covers social data from X, Reddit, YouTube, TikTok, WeChat Official Accounts, and more, which is how you'd monitor a launch like this without scraping. For agents, the MCP server exposes catalog search, price inspection, and runs in one place.
Start with the model catalog, connect an agent at the MCP entry, or give your coding agent skill.md.
FAQ
What is Space Bunny?
It's an anonymous stealth AI model offered free on OpenRouter (Space Bunny Alpha) and OpenCode (Space Bunny Free) since September 23, 2026. It has a 1M-token context window and accepts text, image, and video input.
Who made Space Bunny?
Nobody has said officially. Independent tokenizer studies by YFarmX and stealthprint place it in the MiniMax family.
Is Space Bunny MiniMax M3.1?
That's unconfirmed. MiniMax announced M3.1-Flash-Preview on September 27, 2026, without linking it to Space Bunny.
Why does Space Bunny say it's ChatGPT?
Testers who fingerprinted it say the stealth setup gives the model no identity, so it improvises one. Self-identification isn't reliable evidence.
Is Space Bunny free, and for how long?
OpenRouter lists it at $0, and OpenCode calls it free for a limited time. Neither gives a firm end date. Stealth previews usually stop being free when the model is officially revealed.
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