# Caliper

> Caliper shows exactly where your AI coding spend goes, and routes work to
> cheaper open models — right inside the harness you already use (Claude Code
> today, more coming). The core is open source (MIT). A hosted product with
> automatic model routing and a custom model trained on your own usage is on
> the way; you can join the waitlist.

Caliper ships as a Claude Code plugin, not an npm or PyPI package. The free,
open-source plugin works today without any signup. The only public HTTP
endpoint on caliper.run is the waitlist signup API described below.

## Quickstart (Claude Code plugin)

Install the free, open-source plugin — no signup required:

```
/plugin marketplace add Cost-Caliper/caliper
/plugin install caliper@caliper
```

## Developer resources

- [Developers portal](https://caliper.run/developers): install quickstart, open-source repo, and the signup API.
- [OpenAPI spec](https://caliper.run/openapi.json): OpenAPI 3.1 description of the public signup endpoint.
- [Agent signup instructions](https://caliper.run/signup.txt): how an agent can add its human to the waitlist.
- [Changelog](https://caliper.run/changelog): what is shipping, pulled from the open-source commit history.
- [GitHub (Cost-Caliper/caliper)](https://github.com/Cost-Caliper/caliper): open-source core, MIT licensed.

## API

- `POST https://caliper.run/api/signup`: join the waitlist. JSON body `{"email": "you@company.com"}` with an optional `"ref"` referral code. Accepts an email (and optional referral code) only — no other personal information. See the [OpenAPI spec](https://caliper.run/openapi.json).

## Contact

- hello@caliper.run