TypeScript SDK - Tetlith

@tetlith/ts-sdk wraps the REST API in a typed client: request and response shapes come straight from the same OpenAPI spec that generates the API reference, and the signed-request auth described in Authentication is handled for you.

npm install @tetlith/ts-sdk

pnpm add @tetlith/ts-sdk

yarn add @tetlith/ts-sdk

Quickstart

import { Tetlith } from "@tetlith/ts-sdk";

const tetlith = new Tetlith({ auth: { apiKey: process.env.TETLITH_API_KEY! } });

const entity = await tetlith.entities.create({ externalId: "cus_4821", assets: ["USDC_ETH"] });

Resources

A named method per endpoint, grouped the way the API reference groups them: entities, accounts, transactions, activity, compliance, policies, treasury, reconciliation.

await tetlith.entities.openAccounts(entity.id, { assets: ["USDC_ETH"] });
await tetlith.accounts.getBalance(accountId);
await tetlith.transactions.list({ status: "completed", limit: 20 });

tetlith.api is still there underneath — the same typed openapi-fetch client, usable directly (tetlith.api.POST("/v1/entities", { body })) as an escape hatch for an endpoint the resources haven’t caught up to yet.

Auth

Bearer

{ apiKey }. Simple, and enough for anything read-only.

Signed

{ keyId, signingPrivateKey }. Binds each request to its method, path, body, a timestamp and a nonce with an Ed25519 signature, so a captured request can’t be replayed or altered. Required for anything that moves money.

const tetlith = new Tetlith({
	auth: { keyId: "kp_live_...", signingPrivateKey: process.env.TETLITH_SIGNING_KEY! },
});

Errors

Every non-2xx response throws a TetlithError carrying the API’s own code and status, rather than a response you have to check manually.

import { Tetlith, TetlithError } from "@tetlith/ts-sdk";

try {
	await tetlith.entities.get(entityId);
} catch (err) {
	if (err instanceof TetlithError) {
		console.error(err.code, err.message);
	}
}

Webhooks

constructWebhookEvent verifies the signature and timestamp before handing back the parsed payload — see Webhooks for the event types it carries.

import { constructWebhookEvent } from "@tetlith/ts-sdk";

const event = constructWebhookEvent(
	rawBody, // the exact bytes your server received, not a re-serialised object
	{
		"x-keypair-timestamp": req.headers["x-keypair-timestamp"],
		"x-keypair-signature": req.headers["x-keypair-signature"],
	},
	process.env.TETLITH_WEBHOOK_SECRET!,
);

Source and issues

The SDK is open source — read the code, file an issue, or open a PR.