# OpenAI API vs Together AI: who uses which

On usedby, 5 companies use OpenAI API and 33 use Together AI. 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: 37 of 38 public lines checked.

## Side by side

|  | [OpenAI API](https://www.usedby.ai/tools/openai-api.md) | [Together AI](https://www.usedby.ai/tools/together-ai.md) |
|---|---|---|
| Public customers | 5 | 33 |
| Confirmed | 0 | 18 |
| Observed | 4 | 15 |
| Signals (job posts) | 1 | 0 |
| Top industries of customers (every proof level) | Biotech & Pharma (1), DevTools & Infrastructure (1), Marketing Tech (1) | Artificial Intelligence (17), DevTools & Infrastructure (4), HealthTech & Digital Health (3) |
| Category | Foundation models & model APIs | AI inference & GPU cloud |
| Security | — | SOC 2 Type II, ISO 27001 ([trust.together.ai](https://trust.together.ai/), checked 2026-10-07) |
| Data processing terms | — | A data processing agreement is available. ([trust.together.ai](https://trust.together.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, OpenAI API | Proof, Together AI | First public proof, OpenAI API | First public proof, Together AI |
|---|---|---|---|---|
| [Cursor](https://www.usedby.ai/companies/cursor.md) | Observed | Confirmed | On or before October 2026 | On or before April 2026 |

## Published results

Reviewed stories only; usedby did not measure the figures.

- Together AI: [Arcee AI](https://www.usedby.ai/case-studies/arcee-ai-together-ai.md): **95%**: “Time to First Token (TTFT): Improved by up to 95%” (captured by usedby 2026-10-09)
- Together AI: [Latent Health](https://www.usedby.ai/case-studies/latent-health-together-ai.md): **7x**: “7x cost reduction” (captured by usedby 2026-10-09)

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