Stealth Models, and How They End

Space Bunny is the latest in a year-long line of anonymous stealth models. Every previous one was eventually claimed. Here is the full record, and what it predicts.

What Is a Stealth Model?

A stealth model is an AI model that goes public before its maker does. It shows up on a platform like OpenRouter under a codename, with the provider listed only as "Stealth," a price of zero and a line saying the developer "has chosen to remain anonymous during this preview." Developers try it, share results and guess the owner. Days or weeks later, a lab steps forward, the codename turns into a real product name, and the price goes up.

Space Bunny Alpha is the latest stealth model on OpenRouter, but the format is now well established. In 2026 alone there have been at least eight OpenRouter stealth listings, and other platforms have joined in. Cline and Vercel host their own stealth models, including Pixel Canary, and OpenCode offers stealth models such as Big Pickle and Omen Alpha to its users.

Every OpenRouter Stealth Model of 2026

Codename, first appearance and the lab that turned out to be behind it. Updated September 30, 2026.

Stealth codenameAppearedTurned out to beNotes
Pony AlphaFeb 2026Z.ai GLM-5Claimed in about five days.
Hunter AlphaMar 11, 2026Xiaomi MiMo-V2-ProThe community first guessed DeepSeek, and got it wrong.
Healer AlphaMar 11, 2026Xiaomi MiMo-V2-OmniLaunched alongside Hunter Alpha.
Elephant AlphaApr 2026Ant Group Ling-2.6-flashClaimed roughly two weeks later.
Owl AlphaApr 2026Meituan LongCat-2.0Confirmed in June, the longest wait of the year.
Ox AlphaAug 20, 2026Z.ai GLM-5.3-FlashRevealed Aug 26 after ~24T tokens and 8M sessions. Tokenizer matched GLM 95 of 95 probes.
Union AlphaSep 16, 2026Unbiased Pareto 26.9Free for about 33 hours, now $2.50 / $7.50 per million tokens.
Space Bunny AlphaSep 23, 2026Unclaimed (MiniMax suspected)1M context, #3 in weekly OpenRouter volume, free reported to Oct 5.

The pattern is clear. Seven of seven earlier 2026 stealth models were claimed, and most came from Chinese labs: Z.ai, Xiaomi, Ant Group and Meituan. The exception was Union Alpha, which turned out to be a multi-model system from Unbiased. The reveal usually came within one to two weeks, and the free price ended the day the name went public.

Earlier Stealth Models (2025)

The stealth format predates this year. In April 2025, Quasar Alpha and Optimus Alpha appeared on OpenRouter and turned out to be early versions of OpenAI's GPT-4.1. Later that year, Sonoma Sky Alpha and Sonoma Dusk Alpha brought 2M-token context windows and were revealed as xAI's Grok 4 Fast. Cline's stealth coding model Sonic also turned out to be an xAI model.

Those early cases involved US labs. The 2026 stealth model wave has leaned heavily toward Chinese labs, which use the free anonymous window to win developer attention in Western markets before their brand is known there.

Why Labs Launch Stealth Models

  • Honest feedback. Without a brand attached, developers judge the stealth model on output alone. There is no hype effect and no bias against a lesser-known lab.
  • Scale testing. A free listing draws enormous traffic. Ox Alpha processed around 24 trillion tokens before its reveal, which would be impossible to buy as a controlled test.
  • Safe failure. If a stealth model has bugs, outages or odd behavior, like the Space Bunny launch-day outage, the criticism lands on a codename, not on the company.
  • A marketing moment. The mystery drives coverage. "Who made Space Bunny?" has become a talking point on its own, and the reveal becomes a second news cycle.

How to Unmask a Stealth Model

The community has built a toolkit for identifying stealth models, and some methods are far more reliable than others:

  1. Tokenizer fingerprinting (strong). Send carefully chosen strings and compare token counts with public tokenizers. This identified Ox Alpha as GLM and points Space Bunny to MiniMax.
  2. Spec matching (strong once a candidate launches). Compare context size, effort levels and modalities with newly announced models. Space Bunny's spec sheet matches MiniMax M3.1 Flash Preview.
  3. Error traces (strong when they happen). Ox Alpha once returned an error message that named the provider's own API route.
  4. Behavior and style (weak). Reasoning style, refusal patterns and language slips give hints but are easily confused by distillation.
  5. Asking the model (weakest). Models often invent or borrow identities. Space Bunny has called itself MiniMax and has also signed commits as Claude.

What This Predicts for Space Bunny

If Space Bunny follows the stealth model record, three things are likely:

  • A reveal soon. Space Bunny has already outlasted Ox Alpha's six days and Union Alpha's 33 hours. The reported October 5 end of the OpenCode free window is a natural reveal date.
  • The end of free access. Every past stealth model moved to paid pricing on reveal. If Space Bunny is MiniMax, expect low prices near MiniMax M3's rates.
  • A MiniMax name. The tokenizer evidence is as strong as it was for Ox Alpha. The most likely reveal is MiniMax M3.1 or an M3.1 Flash variant.
Stay current: We will update this stealth model table and our Space Bunny identity page the moment a reveal lands.

Stealth Model FAQ

What is a stealth model?
A stealth model is an AI model released under a codename without the developer's name, usually free for a short preview. OpenRouter, OpenCode, Cline and Vercel have all hosted stealth models. Space Bunny Alpha is the best-known current example.
Why do labs release stealth models?
Anonymity gets honest feedback without brand bias, large amounts of real-world traffic for testing, and protection from bad press if the model has problems. The lab reveals itself once the model is ready.
Are stealth models always revealed?
In practice, yes. Every OpenRouter stealth model of 2026, including Pony, Hunter, Healer, Elephant, Owl, Ox and Union Alpha, was eventually claimed by a named lab, usually within days to a few weeks.
Are stealth models safe to use?
They are fine for experiments but risky for sensitive work. The provider is unknown, prompts may be retained, and the route can change or vanish without notice. Keep secrets and customer data out of any stealth model, Space Bunny included.
Do stealth model names hint at the maker?
No. Codenames like Pony, Owl, Ox, Union and Space Bunny have never reliably pointed to the developer. Tokenizer fingerprints and spec sheets are far better clues.

Keep reading

Who Made Space Bunny?

Applying the stealth playbook to the current mystery model.

Pixel Canary

The other stealth model released the same week, on Vercel and Cline.

Space Bunny Overview

Specs, timeline and where to use the newest stealth model.