# Bring your own backend.

Any server with [the same interface as Jev](/install/backends/system-one/) can answer. Name it with `--url`.

`thinkthen check` sends four fixed requests to check that a server works. With `--plan`, it prints its plan and sends nothing.

The numbers come from [the check specification](https://github.com/botassembly/thinkthen/blob/main/specification/check.md).

## Run it

*The check names the address and the model it would ask.*

```
thinkthen check \
  --plan \
  --url https://your-server/v1 |
head -n 4
```

*Output*

```
url https://your-server/v1/systemone
provider systemone
model asked unspecified
model sent jev-1.13.0
```

*exit 0*

## The lesson

A bar tuned on one model does not carry to another. Run `audit` again on your labeled records before you trust a new backend.

A new model needs its own bar.

On GitHub: [github.com/botassembly/beatles-bench](https://github.com/botassembly/beatles-bench)