Express and Node

Send

The client is the same everywhere — it is fetch and a key, with no Node-only dependency in the call path.

import { createLath } from "@trylath/sdk";

const lath = createLath({ key: process.env.LATH_API_KEY });
await lath.email.send({ to: "you@example.com", subject: "Hello", text: "First one." });

Protect routes

lathExpress verifies the bearer token and puts the user on req.lath. A request without a valid one is answered 401 with www-authenticate: Bearer and the usual { error: { code, message, fix } } body — the middleware never hands a half-authenticated request to your handler.

import express from "express";
import { lathExpress } from "@trylath/sdk";

const app = express();
app.use("/api", lathExpress({ environmentId: process.env.LATH_ENV_ID! }));

app.get("/api/me", (req, res) => res.json(req.lath));

Without a framework

userFromNodeRequest takes a raw Node request and returns the user or null, which is everything Fastify, Koa or node:http needs.

import { createServer } from "node:http";
import { userFromNodeRequest } from "@trylath/sdk";

createServer(async (req, res) => {
  const user = await userFromNodeRequest(req, { environmentId: process.env.LATH_ENV_ID! });
  if (!user) {
    res.statusCode = 401;
    return res.end();
  }
  res.end(JSON.stringify({ userId: user.userId }));
}).listen(3000);

Last modified on September 13, 2026

Overview

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Frameworks

Sending

Platform

Surfaces

Express and Node