Inception's Mercury 3 diffusion LLM claims frontier-level quality at over 1,000 tokens per second
- Mercury 3 is a diffusion-based LLM that Inception says outperforms GPT-6 Luna and Claude Haiku 5.5 on a range of benchmarks while running 4 to 8x faster at 1,068 tokens per second on NVIDIA GPUs.
- Inception says it scaled Mercury more than 40x in total parameters since Mercury 1 and that intelligence rose 3x from Mercury 1 (mini) to Mercury 3, which it presents as proof that diffusion scales like autoregressive models.
- Context window grows to 1M tokens from 260K for Mercury 2.5, priced at $0.20 per million input and $0.70 per million output tokens, with a launch discount to $0.10 and $0.35.
- On 50 live Mind2Web browser tasks run by TinyFish AI, Mercury 3 completed 50% of them, ahead of GPT-6.1-Sol, using the same token volume and agent steps as a frontier model at a lower per-token cost.
- Mercury 3 is available through the Inception API Platform, OpenRouter, Baseten, and Vercel, and it is OpenAI API compatible.
Hacker News opinions
Looks excellent, I'm going to try it out soon. Feels like these diffusion models are finally getting competitive with the big autoregressive ones.
I'm Volodymyr, Inception's co-founder and chief scientist. Mercury 3 runs at 1,000+ tokens per second on Blackwell GPUs and costs $0.10 in and $0.35 out at launch. Diffusion generates tokens in parallel, so the speed gap over autoregressive models of the same size grows as reasoning models think longer.
Will you release the weights? I'm curious why DeepSWE is 46% against Haiku's 52%. My guess is the post-training wasn't RL'd as hard on coding. A cheap 1,000 tok/s option would be great for security reviews and repetitive refactors, if it's reliable enough.
Damn, I've been waiting for an open weights model like this. Still no dice.
Are these harder to reason about since they produce tokens non-linearly? We rely on non-latent reasoning to see what the model is thinking.
Google more or less pioneered this category, then seemingly dropped it. My understanding is diffusion doesn't batch across requests the way transformers do, so it doesn't scale economically. If Inception keeps these speeds and prices, Flash and Luna could lose a lot of use cases.
Google's Diffusion Gemma performed a lot worse than its autoregressive equivalent, and the gap got wider on harder benchmarks. The speed benefit got wiped out at scale, so it's not surprising nobody talks about it.
At least on OpenRouter, DeepSeek v4.1 Flash via Together, Baseten, or Fireworks still beats Mercury 3 on latency and intelligence. TTFT is quite slow with Mercury.
I wish they had a coding plan so you could kick the tires before paying API rates.
The medium pelican is better than the high one, so maybe reasoning hurts output past medium. How fast did they generate? That's the actual selling point of this model.