Open-weight models now handle a majority of tokens on Vercel’s AI Gateway. But Anthropic still takes 64% of the spend.

The trend is clear: open-weight models are taking an increasingly large bite out of production AI usage.

On Monday, The New Stack reported that open-weight models accounted for 60% of OpenRouter’s US token consumption in August, with Chinese-developed models making up the majority of that volume. The latest data point hails from Vercel, whose AI Gateway routes tens of trillions of tokens each month across the applications running on its infrastructure.

As per Vercel’s September report, published on Thursday and covering activity through August, open-weight models handled 56% of all tokens routed through the gateway, the first time they have accounted for a majority of monthly token volume. In December 2025, their share was just 7%; by April it had reached 13%, and it rose every month thereafter. Vercel’s previous report, published in August, put July’s open-weight share at 36%.

So the pattern was already clear. But last month, Vercel CEO Guillermo Rauch took to social media to declare that August 22 had been a “record day for open weight share of tokens on Vercel AI Gateway,” accounting for 62% of traffic.

Rauch saw the milestone as just an early indication of where usage is heading, with enterprises still early on the adoption front.

“This is very likely just the start, because enterprise adoption is still early.”

“This is very likely just the start, because enterprise adoption is still early, and harnesses, CLIs, IDEs, SDKs, etc need to be adapted to be model agnostic,” Rauch wrote at the time.

Open-weight token share on AI Gateway: December ’25 to August ’26 (Credit: Vercel)

Tokens and dollars: Anthropic dominates spend

For context, Vercel launched AI Gateway last year as a way for developers to access models from multiple providers through a single interface, saving them from having to manage separate API keys, accounts and rate limits. The service sits between applications and the underlying model providers, routing requests while tracking usage and costs — giving Vercel a useful vantage point into which models its customers are actually running in production.

Token volume, in this context, is essentially a measure of how much model inference is flowing through the gateway. Vercel counts input and output tokens, along with reasoning, cached-input and cache-creation tokens.

While it’s a good proxy for the amount of work being handed to different models, it shouldn’t be confused with the amount of dollars being spent. Open-weight models from the likes of DeepSeek, Moonshot AI and Z.ai are generally cheaper to run than the proprietary models offered by US frontier labs — and so handling 56% of Vercel’s token volume doesn’t mean open-weight models are taking 56% of the money passing through its gateway.

Indeed, Vercel’s data shows that open-weight models accounted for just 14 cents of every estimated dollar spent through AI Gateway in August, despite processing 56% of its tokens. Their share of spending remains far behind their share of usage, although Vercel says the open-weight share of gateway spending is on the rise.

Open-weight share of tokens vs spend on AI Gateway (Credit: Vercel)

Across Vercel’s AI Gateway, the average price per token fell 23.2% in August, marking a third consecutive monthly decline. Among teams that processed more than 10 million tokens in both July and August, the median cost per token fell 7.6%.

Anthropic, meanwhile, has remained remarkably consistent at the spendy end of the market. Its models accounted for 64 cents of every dollar spent through the gateway in August. Vercel says the Claude-creator’s share has never fallen below 61% in any month since December 2025, with its models occupying the top two positions by spend throughout that period — often taking third spot, too.

Top 3 models by spend, by lab. (Credit: Vercel)

Loyalty lies in the model

There has been plenty of movement within that Anthropic share, however. Fable 5 fell from 13.2% of total gateway spend in July to 4.9% in August, while the cheaper Opus 5 climbed to 22.5%. More broadly, Vercel’s data suggests that 90% of teams using Fable reduced their usage, with more moving those workloads to Opus 5 than to any other model.

Opus ultimately gained almost twice as much usage as Fable lost, which Vercel attributes to the newer model handling similar workloads at roughly half the price. Or, in other words, Anthropic kept the dollars even as customers shifted toward a cheaper model within its own lineup.

“Lab loyalty doesn’t follow brand, it follows model profile, and consistency wins.”

“Lab loyalty doesn’t follow brand, it follows model profile, and consistency wins,” Vercel’s report authors note.

Anthropic’s share of spend by model (Credit: Vercel)

This trend was evidenced elsewhere, too. Within five days of Z.ai launching GLM-5.3-Flash, the new model was processing three times the daily volume of GLM-5.2.

But Vercel’s data also suggests customers are more than prepared to cross lab boundaries when a replacement fails to meet the same needs on capability and price: more than three-quarters of the volume lost by Google’s Gemini 3 Flash moved to models from other providers, including OpenAI and Anthropic. And the consequence for Google wasn’t insignificant: its overall share of token volume on the gateway fell from 30% to 5%, with the decline in Gemini 3 Flash alone accounting for 22 of those 25 percentage points.

“When a new model preserves what users valued in its predecessor, the lab retains its customers,” the authors note. “When it doesn’t, those customers fill the need through other providers.”

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