Overview

coss is the official TypeScript SDK. It has zero dependencies, is fully typed and runs on Node.js 22+, Bun, Deno and Cloudflare Workers.

npm install coss

The clientCopy Anchor Link

One client covers every product. Create it once and reuse it. Each endpoint's page in the API reference shows its SDK call in the TypeScript tab; these pages cover how the client itself behaves.

import { Coss } from "coss";

const coss = new Coss({ apiKey: process.env.COSS_API_KEY });
      
const coss: Coss

Hover any identifier in these examples to see its type.

OptionsCopy Anchor Link

const coss = new Coss({
  apiKey: "coss_test_...",
  baseUrl: "https://api.coss.com",
  timeout: 30_000,
  maxRetries: 2,
  dangerouslyAllowBrowser: false,
});

The constructor throws only for programmer errors: a missing API key, or running in a browser without dangerouslyAllowBrowser.

Results, not exceptionsCopy Anchor Link

Every method returns { data, error }. API and network failures come back as error; they are never thrown. Checking error narrows data:

const result = await coss.email.get("email_01k7c8m4q2f3e9v6t5r1n0p8yz");

if (result.error) {
  console.error(result.error.message);
} else {
  console.log(result.data.subject);
                     
data: Email
}

Per-request optionsCopy Anchor Link

Methods take an optional last argument. Every method accepts an AbortSignal; send also takes an idempotency key.

const controller = new AbortController();

await coss.email.send(params, { idempotencyKey: "welcome-user-123", signal: controller.signal });
await coss.email.get("email_01k7c8m4q2f3e9v6t5r1n0p8yz", { signal: controller.signal });

RuntimesCopy Anchor Link

The package is ESM-only and uses nothing but fetch, AbortSignal and crypto.randomUUID. Environment fallbacks read process.env where it exists; on Workers or Deno without env access, pass apiKey (and baseUrl) explicitly.