# Send emails with Next.js Call OpenSend only from Next.js server code: Route Handlers, Server Actions, background jobs, or server-only modules. Never call the SDK from Client Components because the API key would be bundled for users. ## Install ```bash npm install opensend ``` ## Environment variables ```bash OPENSEND_API_KEY=os_your_api_key # Optional for self-hosted deployments: OPENSEND_BASE_URL=http://localhost:3015 ``` Do not use `NEXT_PUBLIC_OPENSEND_API_KEY`. ## Route Handler example Create `app/api/send/route.ts`: ```ts import { Opensend } from "opensend"; const opensend = new Opensend(process.env.OPENSEND_API_KEY, { baseUrl: process.env.OPENSEND_BASE_URL, }); type SendRequest = { email?: string; }; export async function POST(request: Request) { const body = (await request.json()) as SendRequest; if (!body.email) { return Response.json({ error: "email is required" }, { status: 400 }); } const { data, error } = await opensend.emails.send({ from: "OpenSend ", to: body.email, subject: "Welcome", html: "

Thanks for signing up.

", }); if (error) { return Response.json( { error: error.message, code: error.code }, { status: error.statusCode }, ); } return Response.json({ id: data.id }); } ``` ## Server Action example ```ts "use server"; import { Opensend } from "opensend"; const opensend = new Opensend(process.env.OPENSEND_API_KEY, { baseUrl: process.env.OPENSEND_BASE_URL, }); export async function sendInvite(formData: FormData) { const email = String(formData.get("email") ?? ""); if (!email) return { ok: false, error: "email is required" }; const { data, error } = await opensend.emails.send({ from: "OpenSend ", to: email, subject: "You are invited", html: "

Join the workspace.

", }); if (error) return { ok: false, error: error.message }; return { ok: true, id: data.id }; } ``` ## React Email templates React Email components work well in Next.js server files. Install the optional peer dependencies: ```bash npm install react react-dom @react-email/components ``` ```tsx import { Html, Text } from "@react-email/components"; import { Opensend } from "opensend"; function InviteEmail({ workspace }: { workspace: string }) { return ( You were invited to {workspace}. ); } const opensend = new Opensend(process.env.OPENSEND_API_KEY); await opensend.emails.send({ from: "OpenSend ", to: "user@example.com", subject: "Workspace invite", react: , }); ``` ## Runtime guidance Use the Node.js runtime when your route also imports Node-only libraries. The SDK itself uses `fetch`, but template rendering and some application dependencies may require Node APIs. ```ts export const runtime = "nodejs"; ``` For Edge Runtime or middleware, use the REST API with `fetch` instead of importing Node-oriented dependencies.