Lago JavaScript Client

May 13, 2026 · View on GitHub

This is a JavaScript wrapper for Lago API. Works in Cloudflare Workers, Deno, and Node.js. Generated from the Lago OpenAPI document.

Current Releases

Project	Release Badge
Lago
Lago JavaScript Client

Installation

For npm users:

npm install lago-javascript-client

// npm
import { Client, getLagoError } from 'lago-javascript-client';

// Deno
import { Client, getLagoError } from 'https://deno.land/x/lago/mod.ts';

const lagoClient = Client('__YOUR_API_KEY__');

try {
    const { data } = await lagoClient.billableMetrics.createBillableMetric(billableMetric);
} catch (error) {
    const lagoError = await getLagoError<typeof lagoClient.billableMetrics.createBillableMetric>(error);
}

Compatibility

This SDK uses the Fetch API and natively supported Node.js version >= 18. For other Node versions:

Ideally, run Node with the --experimental-fetch flag

Otherwise, polyfill the Fetch API by doing both:

Patching globalThis

Pass a Fetch instance to the Lago client

import { Client } from 'lago-javascript-client';
import fetch from 'node-fetch';

const lagoClient = Client("api_key", { customFetch: fetch });

Usage

Check the Lago API reference

Error handling

Use the get getLagoError<>() utility function to extract the error object and TypeScript type:

try {
    const { data } = await lagoClient.billableMetrics.createBillableMetric(billableMetric);
} catch (error) {
    const lagoError = await getLagoError<typeof lagoClient.billableMetrics.createBillableMetric>(error);
}

Webhook payload types

The SDK exposes TypeScript types for every webhook event Lago emits. The types are generated from the OpenAPI spec, so they stay in sync with the API.

Indexed lookup by webhook_type:

import type { LagoWebhookPayloads } from 'lago-javascript-client';

app.post('/webhooks', (req, res) => {
    const event = req.body as LagoWebhookPayloads['alert.triggered'];
    // event.triggered_alert is fully typed
    console.log(event.triggered_alert.external_customer_id);
    res.sendStatus(200);
});

Discriminated union for handlers that cover multiple events:

import type { LagoWebhookPayload } from 'lago-javascript-client';

function handle(event: LagoWebhookPayload) {
    switch (event.webhook_type) {
        case 'alert.triggered':
            // event.triggered_alert is typed
            return event.triggered_alert;
        case 'invoice.created':
            // event.invoice is typed
            return event.invoice;
        case 'subscription.terminated':
            return event.subscription;
    }
}