GPT-5.1 vs Inkling

Choose GPT-5.1 if you want…

• ✓Larger context window (400K)

Choose Inkling if you want…

• ✓Higher intelligence (Artificial Analysis index 46)
• ✓Lower price ($1.76 / 1M blended)

GPT-5.1

GPT-5.1 earns its place through adaptive reasoning — a system that genuinely calibrates effort to the task, running roughly twice as fast on straightforward queries and digging deeper on complex ones. That mechanical intelligence shows up in the benchmarks: 94% on AIME 2025, 88.1% on GPQA Diamond, and a 76.3% solve rate on SWE-Bench Verified, making it one of the more capable off-the-shelf options for serious coding and research-level math. Users consistently praise how much cleaner the code output is — fewer logic errors, better edge-case handling — and the improved tool-calling reliability makes it a practical choice for production agentic pipelines. The catch is that the Auto-routing variant has frustrated users who found it silently redirecting requests through stricter safety filters without explanation, a criticism that turned OpenAI's own Reddit launch AMA into a notable PR setback. For teams willing to pick the right variant (Instant, Thinking, or Auto) and work within a September 2024 knowledge cutoff, GPT-5.1 offers strong price-to-capability value at $1.25 per million input tokens — cheaper than its GPT-5.2 successor while covering most production needs.

Inkling

Inkling is Thinking Machines Lab's first open-weights model, and on just4o.chat it runs through the Vercel AI Gateway under thinkingmachines/inkling. It is a multimodal MoE with 975B total parameters and 41B active, trained to reason over text, images, and audio in a shared space rather than bolting on separate encoders. Controllable thinking effort lets you trade latency for depth, function calling supports agentic workflows, and a 256k context window on the gateway is roomy enough for long multimodal sessions. It is a base-tier model on just4o.chat, billed at 4 base requests per send before length multipliers, at $1.00 per million input and $4.05 per million output tokens (cached input $0.17). Practical caveats: no native web search on this route, and chat attachments currently emphasize image input even though the model itself understands audio. For teams that want an open, customizable multimodal foundation with ZDR-compatible gateway routing, Inkling is a strong addition.