Corporate use of ChatGPT usually gets discussed in terms of headcount or headlines, how many people use it, or how OpenAI’s own revenue is trending. Less visible is a plainer number: how much of a company’s software budget goes to it, and how that’s moved through the year. Wallester Business’s own transaction data, anonymised and aggregated across all client industries and countries, gives a clean read on exactly that for the first half of 2026.
Between January and June, spend on OpenAI and ChatGPT among Wallester Business clients rose 68.7%, peaking in May at nearly 79% above the January baseline before easing back slightly in June.
A Steady Climb, With One Pullback
Month by month, the trajectory runs mostly one direction. Spend rose from the January baseline through February, March, and April at a fairly steady pace, then accelerated sharply into May, up 24.2% in a single month, before falling 5.7% in June. OpenAI now accounts for 9.7% of what these companies spend in the software category overall, a sizeable share for one vendor.
The June dip is the only break in an otherwise consistent climb, and it’s too early to call it a pattern. More likely, it’s seasonal. One month of pullback after five months of acceleration isn’t much to build a conclusion on.
Where the Money Goes
Most of the transaction volume is small and frequent. ChatGPT’s web and team subscriptions account for 82.1% of all transactions but only 61.4% of total spend, consistent with a lot of individual seats billed on a recurring basis.
The OpenAI developer platform, the API companies use to build ChatGPT into their own products, works the other way around: just 17.1% of transactions but 37.5% of spend, a smaller number of much larger charges.
The API Is Growing Faster Than the Subscriptions
The more telling shift is in where the growth is coming from. Spend on the developer API grew 149.4% between January and June, more than four times the 35.0% growth in ChatGPT subscription spend over the same period. As a result, the API’s share of total OpenAI spend rose from 27.2% in January to 40.3% by June.
That shift points to something beyond more employees signing up for individual ChatGPT accounts. It suggests companies are building OpenAI’s models directly into their own products and workflows, a pattern that shows up as a smaller number of large recurring charges rather than a growing headcount of subscriptions.
How Wallester Business Helps Track Spend Like This
A growing base of small recurring subscription charges, alongside a smaller number of much larger API bills, is exactly the kind of spend that gets lost inside a single shared card statement. Wallester Business is built to keep it visible instead. Companies can:
- Issue a dedicated virtual card for each subscription or vendor, so a ChatGPT bill never gets buried inside a shared card’s statement.
- Set a spending limit on each card, so a subscription upgrade or an API usage spike doesn’t turn into a surprise.
- Pay foreign vendors like OpenAI without a currency conversion fee on top, holding and paying in 10 currencies.
- Attach receipts to every transaction and sync automatically with Xero or QuickBooks, so a growing software bill doesn’t become a reconciliation problem later.
- See every subscription and every card, across every team, from one dashboard, on web or mobile.
If AI tools are becoming a bigger and more complicated part of the software budget, and the API growth here suggests they are, that’s exactly the kind of spend worth being able to see clearly.
Methodology Note:
Data reflects aggregated, anonymised card transaction activity processed across active Wallester Business accounts between January 1, 2026, and June 30, 2026. Spend figures include all Visa merchant descriptors associated with OpenAI and ChatGPT.
