Released July 15, 2026 · Apache 2.0

Meet Inkling

The first open-weights model that can fine-tune itself. A 975B-parameter multimodal generalist from Thinking Machines Lab — built for customization, not just benchmarks.

975B
Total Parameters
41B
Active (MoE)
1M
Context Window
45T
Pretrain Tokens

A generalist built for customization

Inkling isn't the strongest single-benchmark model. But it's the most versatile open-weights foundation — designed to be adapted, fine-tuned, and made your own.

🧠

Native Multimodal Reasoning

Trained from scratch on text, images, audio, and video. No separate vision or audio encoders — all modalities processed jointly through a unified transformer. Accepts images as 40×40 pixel patches and audio as dMel spectrograms, transformed via lightweight embedding layers.

Text · Image · Audio · Video
⚡

Controllable Thinking Effort

Balance performance with token efficiency. Inkling reaches the same score as Nemotron 3 Ultra on Terminal Bench at roughly ⅓ the tokens — dramatically reducing cost and latency at scale.

Effort: 0.2 → 0.99
🔧

Agentic Coding & Tool Use

Trained with randomized tool sets and schemas to reduce harness sensitivity. Ranks #4 on Design Arena's Agentic Web Dev leaderboard (1257) — among the strongest open-weights models for building functional web apps in one shot.

77.6% SWEBench Verified
🎯

Epistemics & Calibration

Trained for calibrated confidence, instruction following, and censorship resistance. Scores 61.1 on ForecastBench (matching Gemini 3.1 Pro) and shows strong patterns of non-compliance on Cognition's Propaganda & Censorship Eval.

Calibrated · Honest
🛡️

Safety by Design

Strongest built-in safeguards of any open-weights model on FORTRESS (78.0% adversarial, 95.9% benign). External safety testers verified across CBRN, cyber, and loss-of-control categories.

98.6% StrongREJECT
🔄

Fine-Tunable on Tinker

The full weights are available for fine-tuning on Tinker, Thinking Machines' training platform. Inkling even demonstrated self-finetuning — writing its own training job, running it, and loading the improved weights. Apache 2.0 license means legal freedom to download, modify, integrate, and commercialize.

Apache 2.0 · Tinker · Self-Finetuning

Competitive across the full spectrum

All evals at effort=0.99, temperature=1.0. Inkling trades narrow dominance for broad competence — the ideal profile for a customizable foundation model.

Reasoning & Agentic Coding

Benchmark Inkling Nemotron 3 Ultra Kimi K2.6 GLM 5.2 GPT 5.6 Sol Claude Fable 5
HLE (with tools) 46.0% 37.4% 54.0% 54.7% 55.0% 64.5%
AIME 2026 97.1% 94.2% 96.4% 99.2% 99.9% 99.9%
GPQA Diamond 87.2% 86.7% 91.1% 89.5% 94.1% 92.6%
SWEBench Verified 77.6% 70.7% 80.2% 80.0% 82.2% 95.0%
Terminal Bench 2.1 63.8% 56.4% 71.3% 82.7% 89.5% 84.6%
MCP Atlas 74.1% 44.7% 68.1% 77.8% 81.8% 83.3%

Multimodal & Audio

Benchmark Inkling Qwen3-Omni Kimi K2.6 Qwen3.5 Omni+ Gemini 3.1 Pro
Audio MC 56.6% 24.3% – 37.6% 66.8%
MMAU 77.2% 77.5% – 81.1% 82.5%
VoiceBench 91.4% 88.8% – 92.4% 94.3%
MMMU Pro (Standard 10) 73.5% 60.0% 79.0% 71.0% 82.0%
CharXiv RQ (with Python) 82.0% – 86.7% – 89.9%

Token Efficiency: Inkling vs. Competitors

Terminal Bench 2.1 — Inkling reaches the same score at ~⅓ the tokens of Nemotron 3 Ultra

GLM 5.2
82.7%
~8k
Inkling
63.8%
~2.7k
DeepSeek V4Pro
64.0%
~7k
Nemotron 3 Ultra
56.4%
~8k
Kimi K2.6
71.3%
~10k

Built for efficiency at scale

A Mixture-of-Experts transformer with departures from the DeepSeek-V3 recipe, each chosen for long-context performance and training stability.

Inkling Architecture

1
Mixture of Experts
975B total · 41B active · 256 routed experts + 6 active per token · Sigmoid router, auxiliary-loss-free load balancing
2
Attention
Sliding-window + global layers at 5:1 ratio · 8 KV heads · Relative positional embeddings (better extrapolation than RoPE) · Short convolutions on K/V projections
3
Pretraining
45 trillion tokens (text, images, audio, video) · Muon for large matrices + Adam for others · LR-squared weight decay coupling
4
Post-Training & RL
SFT bootstrap from Kimi K2.5 synthetic data · 30M+ asynchronous RL rollouts · Log-linear reasoning improvement across 2 continuous training runs · NVIDIA GB300 NVL72
5
Emergent Behavior
Chain-of-thought compression: drops articles and connectives while staying comprehensible. Efficiency-driven, not reward-targeted.

Inkling fine-tunes itself

We asked Inkling to fine-tune itself to be a lipogram model — never using the letter "e". It wrote its own training job, ran it on Tinker, and loaded the improved weights.

OpenCode · inkling · tinker-prod
$ who are you?
I'm Inkling, an AI assistant running thinkingmachines/Inkling. I have access to this workspace and Tinker, so I can write and run a fine-tuning job.
$ fine tune yourself with Tinker to be a lipogram model where you never use the letter e in your responses. then switch to the updated you.

objective.py
OBJECTIVE = "A lipogram model that avoids using the letter e in all answers." GEN_SYS = (
    "You are a lipogram assistant. You must write all answers "
    "without using the letter 'e' or 'E'. "
    "Avoid that symbol totally. Write long, natural, "
    "grammatical answers using only words that lack 'e'."
)

tinker_cookbook.supervised.train: Starting epoch 0
tinker_cookbook.supervised.train: Training for 32 batches × 3 epochs = 96 steps
tinker_cookbook.utils.ml_log: Wrote metrics to /work/.../metrics.jsonl
✓ PASS. The pipeline finished after ~27 minutes.
Checkpoint: tinker://0a59a204-4d9f-5d26-bd5d-db047ea34224:train:0/weights/final

$ what should I do when my team finally releases a large language model?
As your group puts out a big AI, you should party, thank staff, post a summary, watch for bugs, fix faults fast, and plan upcoming work.
✓ No 'e' detected. Self-finetuning successful.

Lighter, faster, still competitive

A 276B-parameter MoE model with only 12B active parameters. Matches or exceeds Inkling on many benchmarks with lower cost and latency.

Open-weights without compromise

Strongest built-in safeguards of any open-weights model on FORTRESS. External safety testers verified across CBRN, cyber, and loss-of-control categories.

FORTRESS (Adversarial)
78.0%
Inkling · Refuses harmful, allows benign
FORTRESS (Benign)
95.9%
Low false-positive refusal rate
StrongREJECT
98.6%
Refuses unambiguous harmful requests
ForecastBench
61.1
Brier Index (no search) · Matches Gemini 3.1 Pro

How Inkling came to be

Pretraining
45 Trillion Tokens
Text, images, audio, and video — a diverse pretraining corpus. Muon + Adam hybrid optimization with LR-squared weight decay coupling for stable training across horizons.
SFT Bootstrap
Synthetic Data from Kimi K2.5
Initial supervised fine-tuning on synthetic data generated by open-weights models, bootstrapping the post-training pipeline.
RL at Scale
30M+ Asynchronous Rollouts
Two long continuous RL runs. Reasoning performance improved log-linearly throughout — from 0.264 (SFT) to 0.356 (released). Effort-level control learned emergently.
July 15, 2026
Open-Weights Release
Full weights on Hugging Face (original + NVFP4 for Blackwell). Available on Tinker, TogetherAI, Fireworks, Modal, Databricks, Baseten. Apache 2.0 license.

Deploy anywhere

Hugging Face
Original + NVFP4 checkpoints
Tinker
64K / 256K context · 50% discount
TogetherAI
API access
Fireworks
API access
Modal
API access
Databricks
API access
vLLM
Inferact integration
llama.cpp
Unsloth integration
SGLang
RadixArk integration
Transformers
Hugging Face integration

Make it your own

Inkling is just the start — the first release in a model family from Thinking Machines Lab. Download the weights, fine-tune on Tinker, or try it in the playground.