Thinking Machines Lab Releases Inkling, Their First Open-Source AI Model

Inkling was just released on July 15, 2026 by Thinking Machines Lab, the AI startup founded by former OpenAI CTO Mira Murati. It's a significant release because it's the company's first in-house AI model, and unlike the flagship models from OpenAI, Anthropic, or Google, it's open-weight, meaning outside developers and companies can download it and modify it directly.

This is, hands down, the largest open-source AI model that any American AI lab has made, which makes it even more important, as China is slowly taking over the open-source AI market.

## The Specs

Inkling is a massive model with 975 billion parameters in total, but it doesn't use all of them at once. Thanks to its Mixture-of-Experts design, it only activates about 41 billion parameters for any given task. That's what keeps it fast and affordable to run despite its size.

It also has a context window of up to 1 million tokens, but when served with Tinker, it comes in only 64K and 256K context window variants.

Under the hood, it's a 66-layer transformer. Instead of one big neural network doing all the work, it splits tasks across 256 specialized expert sub-networks (plus 2 that are always on), but only 6 of those experts get used per token.

## Benchmark & Practical Utility

On the Artificial Analysis Intelligence Index, Inkling receives a 41. While not topping the raw scoreboards, Thinking Machines Lab offers Tinker—a platform for fine-tuning Inkling on private domain data. In early tests with financial firms, fine-tuned Inkling variants outperformed frontier proprietary models at under 10% of the cost.