A tiny, dependency-free client for the GREM API. It works in Node 18+ and modern browsers (uses the global fetch and Web Crypto).
Install
It is a single file — no build step, no dependencies. Download it and drop it into your project:
Quickstart
import { GremClient } from './grem';
const grem = new GremClient({ apiKey: process.env.GREM_API_KEY });
const { estimate } = await grem.valuation.express({
propertyCategory: 'apartment',
totalArea: 50,
});
console.log(estimate.pricePoint, estimate.currency);
The base URL defaults to https://developers.grem.capital/api/v1. Create a key in the cabinet: AI tools -> API -> Keys.
Async jobs
Long-running tools return a jobId. Poll for the result (polling is free):
const { jobId } = await grem.content.generate({ /* ... */ });
const result = await grem.jobs.wait('content/generate', jobId);
Errors
Non-2xx responses throw a GremError (RFC 7807):
import { GremError } from './grem';
try {
await grem.valuation.express({ propertyCategory: 'apartment' }); // missing totalArea
} catch (e) {
if (e instanceof GremError) console.error(e.status, e.detail, e.requestId);
}
Idempotency
Pass an idempotency key to safely retry a POST:
await grem.valuation.express(input, crypto.randomUUID());
Webhooks
Verify each delivery's signature against the raw body:
import { verifyWebhookSignature } from './grem';
app.post('/grem-hook', express.raw({ type: 'application/json' }), async (req, res) => {
const raw = req.body.toString('utf8');
const ok = await verifyWebhookSignature(process.env.GREM_WEBHOOK_SECRET, req.get('x-grem-signature'), raw);
if (!ok) return res.status(400).send('invalid signature');
const event = JSON.parse(raw);
// handle event.type / event.data ...
res.sendStatus(200);
});
Every method maps 1:1 to an endpoint in the interactive explorer. See Quickstart and Webhooks for the underlying requests.