The OpenAI Assistants API is a developer building block on OpenAI’s models; osFoundry is a managed, model-neutral platform. Here’s an honest comparison for 2026. (dgm implements osFoundry as an independent partner; we’ll be fair to both.)
At a glance
| OpenAI Assistants API | osFoundry | |
|---|---|---|
| What it is | Developer API (OpenAI) | Managed AI platform |
| You | Build the app around it | Configure & use it |
| Models | OpenAI only (single-vendor) | Model-agnostic, bring-your-own-key |
| Effort | High (engineering) | Lower (prebuilt) |
| Hosting | OpenAI platform | Self-host or US/EU/JP |
As of 2026 — confirm with OpenAI.
What each is
The OpenAI Assistants API is a developer building block for creating AI assistants on OpenAI’s models (tools, retrieval, threads) — you build the application around it, and it’s single-vendor.
osFoundry is a managed, multi-model platform with orchestration prebuilt — chat, agents, apps, knowledge — model-agnostic via bring-your-own-key, and self-hostable.
Two key differences
- Single-vendor vs model-agnostic — the Assistants API ties you to OpenAI; osFoundry lets you use OpenAI and switch or mix providers. (See how to avoid vendor lock-in.)
- Build vs use — the Assistants API is a building block you engineer around; osFoundry is a prebuilt platform needing less engineering. (See build vs buy.)
Data control
The Assistants API runs on OpenAI’s platform. osFoundry self-hosts in your own UK/EU cloud, uses its EU region (US/EU/JP, no UK region), or runs local inference — the more direct route for strict UK data control.
Who each is best for
- OpenAI Assistants API — developer teams building custom assistants on OpenAI.
- osFoundry — businesses wanting a ready-to-use, model-flexible platform with less engineering.
Which should a UK business choose?
Developers building custom on OpenAI? The Assistants API. Want a ready-to-use, model-neutral platform? osFoundry — and dgm can help you evaluate and implement.
dgm is an independent integration partner with zero integrations so far. To compare these, book a consultation with dgm. General information; verify current vendor terms.