Fireworks AI vs OpenAI API: who uses which
Customers, public proof and the companies that use both.
On usedby, 29 companies use Fireworks AI and 5 use OpenAI API. 1 company uses both, including Cursor. Fireworks AI leads among the Artificial Intelligence companies on usedby that use either tool.Latest check Oct 14, 2026: 33 of 34 public lines checked. Counts include every proof level, job-post signals included. A company on both tools counts at any proof level, and a job post on one side is marked as such.
Who uses Fireworks AI, OpenAI API, or both
Every company with a public proof for at least one of the two tools.
28
use only Fireworks AI
1
company uses both
4
use only OpenAI API
28 companies use only Fireworks AI, 4 use only OpenAI API and 1 uses both, out of the 33 companies on usedby that use at least one of them.
Who uses both
Companies with a public line on both tools, at any proof level: the strongest proofs come first, and a job post is marked.
| Company | First public proof, Fireworks AI | First public proof, OpenAI API |
|---|---|---|
 Cursor | On or before May 2025 | On or before Oct 2026 |
By industry
Which tool the companies on usedby use, by industry. Shares of the companies on usedby that use Fireworks AI, OpenAI API or both: a share of the companies on usedby, not of the market.
Fireworks AI onlyBothOpenAI API only
More common with Fireworks AI
- Artificial Intelligence9 of the 9 Artificial Intelligence companies on usedby that use either tool use Fireworks AI.
- DevTools & Infrastructure9 of the 9 DevTools & Infrastructure companies on usedby that use either tool use Fireworks AI, 1 of them alongside OpenAI API.
Source: every usedby line, from confirmed proofs to job-post signals (the weakest proof level).
Side by side
Facts from our data and from each vendor's public pages. Each line says where it comes from.
Fireworks AI
OpenAI APIWhat customers report
Results as the vendor or the customer published them, with the source and the date.
Questions about Fireworks AI and OpenAI API
Which is used more, Fireworks AI or OpenAI API?
Fireworks AI has more customers on usedby: 29 against 5 for OpenAI API.
Do companies use both Fireworks AI and OpenAI API?
Yes. 1 company uses both on usedby, including Cursor.
Who uses Fireworks AI?
29 companies on usedby, each with the public page that shows it. See who uses Fireworks AI.
Who uses OpenAI API?
5 companies on usedby, each with the public page that shows it. See who uses OpenAI API.
How does usedby count customers?
A company counts when a public page shows it: a vendor's customer page, a case study, a press release or a job post, most saved with a dated capture. Every line is a customer, at one of three proof levels: confirmed, observed or signal (a job post, the weakest). A company counts as using both tools when it has a line on each, at any level; the list shows the strongest proofs first and marks job posts.