The Gemini 3.5 checkpoint just leaked, and developers are losing their minds.
Google hasn’t officially announced Gemini 3.5 yet.
But users inside AI Studio are finding a secret version — one that’s smarter, slower, and 40% more accurate than Gemini 3 Pro.
And if the data is real, this Gemini 3.5 checkpoint is quietly the most advanced model Google has ever shipped.
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How the Gemini 3.5 Checkpoint Was Discovered
It started with confusion.
Developers selected Gemini 3 Pro in AI Studio, ran their prompts, and noticed something odd.
Two responses appeared.
The first looked normal — solid but familiar.
The second?
Sharper logic.
Better structure.
Cleaner output.
So they dug deeper.
Inside the browser network logs, they spotted different model IDs — ones starting with “D9,” “D13,” or “Day9.”
These weren’t part of the public Gemini 3 Pro models.
They were unlisted test checkpoints, running quietly inside Google’s infrastructure.
The community named it the Gemini 3.5 checkpoint, and what they found next confirmed the leak.
Why the Gemini 3.5 Checkpoint Is a Big Deal
Most AI model updates are incremental.
A bit faster here.
A little smarter there.
But this one’s different.
The Gemini 3.5 checkpoint produces responses that are not just better — they’re meaningfully superior.
Developers reported:
- 40% longer and more coherent answers
- Fewer factual or logical errors
- More detailed explanations
- Cleaner, more optimized code
And perhaps most telling of all — it thinks slower.
While Gemini 3 Pro replies in around 8 seconds, Gemini 3.5 takes up to 25 seconds.
That’s not lag.
That’s deliberate processing.
It’s what Google calls “long-form reasoning.”
The checkpoint spends more time building multi-step logic before answering — similar to how GPT-4 Turbo and Claude 3 handle reasoning depth.
Gemini 3.5 Checkpoint Performance in the Wild
Developers have tested it across multiple disciplines.
In SVG generation tests, Gemini 3.5 produced pixel-perfect results compared to Gemini 3 Pro’s basic output.
When prompted to generate an Xbox controller SVG, Gemini 3 Pro created a functional but flat image.
Gemini 3.5 built a fully layered, professional vector with gradients, shadows, and real-world proportions.
Same prompt.
Completely different class.
In automation tests, the gap grew wider.
Gemini 3 Pro could generate a script that worked — but lacked structure and documentation.
The Gemini 3.5 checkpoint wrote production-ready code complete with functions, comments, and error handling.
Developers described it as “the difference between a junior dev and a senior engineer.”
What Makes the Gemini 3.5 Checkpoint Smarter
The leaked model appears to include three core upgrades:
1. Extended Context Reasoning
It handles longer prompts and remembers prior context better, reducing truncation.
2. Improved Multimodal Awareness
It interprets images, SVGs, and layout structures more precisely.
3. Adaptive Chain-of-Thought
Instead of rushing outputs, it calculates more steps internally — leading to logical, well-supported answers.
This kind of reasoning isn’t just more accurate.
It’s more human.
It reflects the same design shift Google teased with its “Project Astra” demos — models that reason like agents, not chatbots.
Hidden Model IDs Behind the Gemini 3.5 Checkpoint
Multiple users confirmed seeing the following model IDs:
models/gemini-pro-d9models/gemini-pro-d13models/gemini-ultra-experimental
These IDs don’t appear in public documentation.
They indicate internal A/B testing branches — the checkpoints used to train and validate model improvements before an official release.
This means that Gemini 3.5 is not vaporware.
It’s real, live, and being tested publicly — quietly.
How to Access the Gemini 3.5 Checkpoint
Here’s what researchers did to trigger the hidden model.
Go to AI Studio.
Select Gemini 3 Pro as the model.
Enter your prompt and let it start generating.
Stop it halfway through.
Then rerun the exact same prompt.
If you’re lucky, you’ll see two side-by-side outputs.
That’s Google’s internal A/B testing framework activating.
One response comes from Gemini 3 Pro, the other from the Gemini 3.5 checkpoint.
If the output takes longer to generate and feels more “thoughtful,” that’s the one.
You can also press F12, open Developer Tools, check the Network tab, and look for requests containing “D9” or “D13” model IDs.
That’s confirmation you’ve hit the leaked checkpoint.
Benchmark Comparisons: Gemini 3 Pro vs Gemini 3.5 Checkpoint
Here’s what developers are reporting from hundreds of tests:
Reasoning Quality
Gemini 3.5 performs up to 35–40% better in logical and analytical reasoning.
Coding Ability
Produces fully structured, optimized code with documentation and best practices.
Output Detail
Outputs are longer, richer, and more nuanced, with fewer truncations.
Speed
Slower response time — but that’s what gives it deeper reasoning.
SVG and Visual Tasks
The checkpoint version is 3x more accurate at visual spatial tasks.
These consistent gains point to a serious internal upgrade — likely a refined Gemini Ultra architecture or enhanced token expansion.
Why Google Is Quietly Testing Gemini 3.5 Checkpoint
This isn’t the first time Google has run a silent rollout.
They did the same before launching Gemini 1.5.
Running an A/B test inside AI Studio lets them gather real user data, performance metrics, and latency feedback before announcing it.
It’s an invisible beta program — millions of developers unknowingly helping fine-tune Gemini 3.5 for production.
The fact that these tests are live suggests official release is close.
Weeks, not months.
What the Gemini 3.5 Checkpoint Means for Developers
This leak is a preview of where AI development is heading.
With reasoning this advanced, developers can finally build systems that:
- Write entire backend and frontend workflows
- Auto-generate code that follows best practices
- Validate data logic and fix errors before execution
It means faster prototyping.
Cleaner code.
Fewer manual revisions.
For serious AI builders, this isn’t hype — it’s a technical leap forward.
How This Changes AI Model Design
The Gemini 3.5 checkpoint represents a shift in how models are trained.
Instead of focusing purely on scale, Google is optimizing for quality per token — more intelligent reasoning within fewer steps.
This architecture favors structured outputs, cleaner logic, and contextual accuracy.
It’s a smarter model, not just a bigger one.
That’s the trend defining the new AI generation.
If you want to see how creators and founders are already using Gemini 3.5 Checkpoint to automate real systems, check out Julian Goldie’s FREE AI Success Lab Community: https://aisuccesslabjuliangoldie.com/
Inside, you’ll get access to workflow templates, prompt systems, and automation case studies powered by Gemini, Claude, and Anti-Gravity.
The Road Ahead for Gemini 3.5 Checkpoint
The testing phase is clear proof that Google’s moving fast.
Once the checkpoint stabilizes, it will likely merge into the upcoming Gemini 3 Ultra release or debut as Gemini 3.5 Pro.
We’ll see tighter integration with Google’s ecosystem — from Chrome extensions to Android features — and wider rollout in AI Studio.
If this version ships as-is, it could finally close the reasoning gap between Google and Anthropic’s Claude 3.
That would be huge.
Final Thoughts
The Gemini 3.5 checkpoint is not a rumor.
It’s a real, functioning model that’s already outperforming Gemini 3 Pro across nearly every test.
It’s smarter.
Slower.
And far more capable.
From better code generation to complex logic handling, this checkpoint marks Google’s biggest AI leap since Gemini’s original release.
If you’re a developer or researcher, test it while you can.
You’re witnessing Google’s next-generation model — months before the rest of the world.
FAQs
What is the Gemini 3.5 checkpoint?
It’s an unannounced version of Google’s Gemini AI being A/B tested through AI Studio.
How much better is it?
Roughly 35–40% improvement in reasoning, coding, and accuracy over Gemini 3 Pro.
Why is it slower?
Because it uses longer reasoning chains before generating answers.
Can anyone access it?
Yes, if you trigger the right A/B test sequence in AI Studio.
When will it be released officially?
No date yet, but ongoing public tests suggest it’s coming soon.
