Claude Opus 5 has been leaked early, and netizens have already tested it thoroughly.
In the 3D-generated scene posted by @chetaslua, a slingshot is aimed at a castle wall, launching stone projectiles. On the left side of the frame, parameter cards displaying trajectory tension, projectile weight, and other details are clearly displayed.
He said that after using Opus for so long, he had never seen such detail in a single frame—even taking multiple screenshots couldn’t produce the same effect.
Similar reactions have been popping up these past few days, with some even saying they’re willing to call it Fable 6.
Of course, this video isn't an isolated case—over the past couple of days, others have continued to share additional real-world tests.
Netizens are already trying out Opus 5
@chetaslua didn't just post one video.
On the same day, he unveiled another weather card interface where light and shadow shift over time; on sunny days, the sun casts its glow onto a frosted glass panel, and as clouds drift by, the shadows move accordingly.
There’s also a kitchen scene, complete with refrigerator magnets, grout lines between the tiles, and a reflective kettle on the stove.
He summed up these effects in one sentence, saying that after using Opus for so long, this was the first time he felt Three.js could achieve such a texture.
Some netizens have even found that Opus 5's handling of this scenario has surpassed Fable.
@birdabo conducted a head-to-head comparison.
For the same siege scene with a slingshot, he generated it separately using Opus 5 and the already launched Fable 5.
Although Fable 5 was created in one go, the tent is a flat, solid color, the grass lacks undulations, and the slingshot lacks parameter panels for tension and arrow weight, making its detail density visibly inferior.
At the same time, @xikhar released a completely different scenario—a Minecraft recreation and test.
Having the model replicate Minecraft has become a classic problem.
In the demo shown by the blogger, the physics of the blocks shattering and the shadows cast by the lighting are replicated with remarkable accuracy.
He later posted an SVG image of a PS5 controller, with reflections and shadows on the joysticks, touchpad, and buttons rendered to look like a photorealistic image.
The blogger therefore commented that Opus 5 is "strong in both 3D and 2D."
Opus 5 is beginning to emerge
Regarding the Opus 5 leak, the earliest traces appeared on July 9.
That day, a code name called Honeycomb EAP appeared in Cursor's model selector.
The key point is that this mysterious model is listed alongside Opus 4.8 and Sonnet 4.5, with a标注 of a 1M context window and a tier called “extra high effort.”
A few hours later, the mysterious model disappeared again.
On July 14, another netizen posted that they found an entry for Opus 5 in the Google Vertex AI model library.
The blogger estimates the model will be officially released as early as Thursday, and also mentioned a concern that Anthropic might use this as an excuse to remove Fable 5 from the Claude subscription plan.
The next day, another blogger posted the same message.
Last night, @M1Astra posted a new thread stating that signs of preliminary preparation for Opus 5 have appeared once again.
Shortly after, he added another update stating that Opus 5 has begun rolling out across various providers.
This morning, he updated again, stating that some users are already using Opus 5; although the interface still displays 4.8, the output difference is clearly noticeable.
Also, a screenshot was leaked this morning.
A screenshot allegedly posted by an Anthropic employee shows that after triggering Fable 5’s guardrail, the system routed him to Opus 5.
In Cursor, Opus 5 also appears under its real name.
The specific location is an error popup displaying the string "claude-opus-5-thinking-high," which states that Max Mode must be enabled to use it.
According to some netizens' speculation, Opus is close to its official launch.
Fable 5 alternative?
As this round of real-world testing gained momentum, claims that Opus 5’s performance can match Fable 5 began to circulate widely.
This claim is appealing because Fable 5 is priced at $10 per million tokens for input and $50 per million tokens for output—exactly twice the rate of the Opus series.
If Opus 5 can truly match the level of Fable 5 but remains priced at the Opus tier, it would be a half-price alternative.
However, as of now, no complete, independently verifiable benchmark has been publicly released.
Also, whether the overall cost is lower cannot be determined by the unit price alone.
The blogger Chetaslua mentioned that Opus 5 consumes tokens even faster than Fable 5, exhausting the quota with just three prompts.
If token consumption is truly so massive, the advantage in unit price will disappear, and the expectation of it being half as cheap will become an illusion.
However, Opus 5 is likely not far from release—whether it can truly replace Fable will be clear soon enough.
Reference link:
[1]https://x.com/chetaslua/status/2080290382315925911
[2]https://x.com/cheatyyyy/status/2080359098214953421
[3]https://x.com/M1Astra/status/2080246754104971356
[4]https://x.com/birdabo/status/2080340647622623315
This article is from the WeChat public account "Quantum Bit," authored by Kresi.