# Fireworks AI vs OpenAI API: who uses which

On usedby, 29 companies use Fireworks AI and 5 use OpenAI API. 1 company uses both, including Cursor. Counts include every proof level, job-post signals included; each company keeps its proof level on each side. Latest check 2026-10-14: 33 of 34 public lines checked.

## Side by side

|  | [Fireworks AI](https://www.usedby.ai/tools/fireworks-ai.md) | [OpenAI API](https://www.usedby.ai/tools/openai-api.md) |
|---|---|---|
| Public customers | 29 | 5 |
| Confirmed | 0 | 0 |
| Observed | 29 | 4 |
| Signals (job posts) | 0 | 1 |
| Top industries of customers (every proof level) | Artificial Intelligence (9), DevTools & Infrastructure (9), HR & Recruiting (2) | Biotech & Pharma (1), DevTools & Infrastructure (1), Marketing Tech (1) |
| Category | AI inference & GPU cloud | Foundation models & model APIs |
| Security | SOC 2 Type II, HIPAA, ISO 27001, ISO 27701, ISO 42001 ([trust.fireworks.ai](https://trust.fireworks.ai/), checked 2026-10-07) | — |
| Data processing terms | A data processing agreement is available. ([trust.fireworks.ai](https://trust.fireworks.ai/), checked 2026-10-07) | — |

## Companies that use both

Every proof level counts; the proof level of each side is shown, strongest proofs first. The first public proof is not an adoption date.

| Company | Proof, Fireworks AI | Proof, OpenAI API | First public proof, Fireworks AI | First public proof, OpenAI API |
|---|---|---|---|---|
| [Cursor](https://www.usedby.ai/companies/cursor.md) | Observed | Observed | On or before May 2025 | On or before October 2026 |

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Source: https://www.usedby.ai/compare/fireworks-ai-vs-openai-api · How we check: https://www.usedby.ai/methodology