A built-in appliance.
Excellent, and it fits right into a TypeScript kitchen. Comes with ready-made parts for chat UIs. If your kitchen runs on something else, it doesn't plug in.
- theloop vs Vercel AI SDK
- 2-minute read
Same engine.
Different address.
Vercel's AI SDK is a great TypeScript library for talking to models, and theloop is literally built on it. The difference is where the agent loop lives: inside your TypeScript app, or behind an HTTP endpoint that any language can call.
In plain words.
A takeaway counter.
Built around the same appliance, but with a window onto the street. Any app that can make an HTTP call can order from it.
Side by side.
| Question | Vercel AI SDK | theloop |
|---|---|---|
| What is it? | An open-source TypeScript library | An open-source HTTP service built on AI SDK 5 |
| Languages | TypeScript and JavaScript | Anything that speaks HTTP, low-code platforms included |
| The agent loop | ToolLoopAgent, inside your process |
One POST /runs, in a separate service |
| Tools | Run automatically when the model calls them, unless you add approval rules | Read tools run. Write tools never do: they answer deferred |
| Billing | Token usage on results, with SDK retries built in | SDK retries off, so every provider attempt gets its own usage record |
| Chat UI | React hooks like useChat for streaming chat Vercel AI SDK wins |
An SSE stream. The UI is yours to build |
| Many customers | You build it into your app | By construction: the whole config arrives with each request |
Which one is yours?
Pick Vercel AI SDK if…
- Your backend is TypeScript, and you want the agent in-process
- It's one product with one configuration, not many customers
- You want ready-made chat UI hooks
Pick theloop if…
- Your backend is Python, Go, PHP, 1C or a low-code platform
- Many customers, each with its own prompt, tools and key
- Writes must go through approval in your system, no exceptions
- Finance wants every provider attempt on the bill
The honest version. Same engine under the hood. If your backend is TypeScript and serves a single tenant, the SDK's own agent is the simpler choice.