Node WebPush (Node.js + TypeScript)

A dependency-free Web Push implementation for Node.js (TypeScript-first).

This library focuses on standards-compliant payload encryption + VAPID authentication, and produces request details that can be sent with Node’s built-in fetch().

Features

✅ Standards & compatibility

• RFC 8188: HTTP Encrypted Content Encoding (record-based framing, per-record nonce derivation).
• RFC 8291: Web Push message encryption (ECDH + auth secret, “WebPush: info” key schedule, aes128gcm).
• RFC 8292: VAPID (JWT ES256) authentication headers.
• Supports both encodings:
  • aes128gcm (recommended): modern Web Push encoding (RFC 8291 + RFC 8188).
  • aesgcm (legacy): kept for interoperability with older endpoints.

🔐 Encryption

• Pure Node.js crypto (no external libs).
• RFC8188 record framing:
  • delimiter rules (0x01 for non-last, 0x02 for last)
  • optional final-record padding
  • nonce = baseNonce XOR SEQ per record

🪪 VAPID

• Native ES256 JWT signing using Node’s crypto (JWK-based key objects).
• Key generation (VAPID.GenerateKeys()).
• Full validation helpers (VAPID.Validate.*).

🧰 Request building

• generateRequest() produces { endpoint, init } for fetch(endpoint, init).
• Sets required headers:
  • TTL, Urgency, optional Topic
  • Content-Encoding, Content-Type, Content-Length
  • Authorization (VAPID or GCM/FCM key when applicable)

⚠️ GCM / FCM edge cases

• Detects legacy GCM endpoints:
  • Uses Authorization: key=<apiKey> (VAPID not supported on legacy GCM).
• Supports FCM endpoints:
  • Uses VAPID by default when configured.
  • Can fall back to Authorization: key=<apiKey> if VAPID is disabled and a key is provided.

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Installation

npm install node-webpush

TypeScript is supported out of the box (the package emits .d.ts).

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Quick start

1) Create a WebPush instance

import {WebPush} from "node-webpush";

const webpush = new WebPush({
    vapid: {
        subject: "mailto:admin@example.com",
        publicKey: process.env.VAPID_PUBLIC_KEY!,
        privateKey: process.env.VAPID_PRIVATE_KEY!,
    },
    // Optional: used for legacy GCM/FCM key-based auth fallback
    gcm: {apiKey: process.env.GCM_API_KEY ?? null},
});

2) Send a notification

const subscription = {
    endpoint: "https://push-service.example/...",
    keys: {
        p256dh: "<base64url>",
        auth: "<base64url>",
    },
};

const res = await webpush.notify(subscription, "Hello from WebPush!", {
    TTL: 60,
});

console.log("Status:", res.status);

---

Generate VAPID keys

import {VAPID} from "node-webpush";

const keys = VAPID.GenerateKeys();
console.log(keys.publicKey);
console.log(keys.privateKey);

You typically store these as environment variables:

• VAPID_PUBLIC_KEY
• VAPID_PRIVATE_KEY

---

API Reference (high level)

new WebPush(config)

type WebPushConfig = {
    vapid: {
        publicKey: string;
        privateKey: string;
        subject: string | URL; // must be https: or mailto:
    };
    gcm?: { apiKey?: string | null };
};

Constructing WebPush validates:

• VAPID subject format (https: or mailto:)
• VAPID key sizes and base64url encoding
• GCM/FCM key if provided (must be non-empty)

---

webpush.generateRequest(subscription, payload?, options?)

Returns the request parameters to call fetch() yourself.

const {endpoint, init} = webpush.generateRequest(subscription, "payload", {
    TTL: 60,
});

const res = await fetch(endpoint, init);

This is useful if you want to:

• inspect headers
• plug into your own HTTP stack
• retry logic / circuit breakers
• log request metadata

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webpush.notify(subscription, payload?, options?)

Sends the request using fetch().

const res = await webpush.notify(subscription, "hello");

default it return the response even if not successful. It can also throw an error if the push service returns a non-2xx response. This can be enabled by:

import {WebPushError} from "./webpush";

try {
  const res = await webpush.notify(subscription, "hello", {
    throwOnInvalidResponse: true //Add this to the options
  });
} catch (error: WebPushError){
    console.error(error);
    const responseObject  = error.response; //<<-- The resulting response object can still be accessed
}

Throws WebPushError when the push service returns a non-2xx response.

This also contains the response but can be handled in the try-catch logic

---

Options

type GenerateRequestOptions = {
    headers?: Record<string, string>;

    TTL?: number; // seconds
    urgency?: "very-low" | "low" | "normal" | "high";
    topic?: string; // base64url <= 32 chars

    contentEncoding?: "aes128gcm" | "aesgcm";

    // RFC8188 knobs (primarily for advanced use/testing)
    rs?: number; // default 4096, must be >= 18
    allowMultipleRecords?: boolean; // default false (Web Push wants single record)
    finalRecordPadding?: number; // default 0

    // Override authentication behavior:
    vapidDetails?: WebPushConfig["vapid"] | null;
    gcmAPIKey?: string | null;
};

Notes

• aes128gcm is recommended for Web Push.
• For Web Push interoperability, leave allowMultipleRecords at false (default).
• topic must use URL-safe base64 characters and be <= 32 chars.

---

Choosing auth method (VAPID vs key)

This library follows typical push-service rules:

1. Legacy GCM endpoint (https://android.googleapis.com/gcm/send...)

• Uses Authorization: key=<gcmAPIKey>
• VAPID is ignored (not supported)

2. Everything else

• If vapidDetails is present: uses VAPID
• Else if endpoint is FCM and a key is present: uses Authorization: key=<gcmAPIKey>

If you want to disable VAPID for a call:

await webpush.notify(subscription, "hello", {
    vapidDetails: null,
    gcmAPIKey: process.env.GCM_API_KEY!,
});

---

Minimal example with manual fetch

import {WebPush} from "node-webpush";

const webpush = new WebPush({
    vapid: {
        subject: "https://example.com/contact",
        publicKey: process.env.VAPID_PUBLIC_KEY!,
        privateKey: process.env.VAPID_PRIVATE_KEY!,
    },
});

const {endpoint, init} = webpush.generateRequest(subscription, "ping", {
    TTL: 120,
    urgency: "high",
});

console.log(init.headers); // inspect headers

const res = await fetch(endpoint, init);
console.log(res.status);

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Error handling

import {WebPush, WebPushError} from "node-webpush";

try {
    await webpush.notify(subscription, "hello");
} catch (e) {
    if (e instanceof WebPushError) {
        console.error("Push service rejected request:", e.response.status);
        console.error("Response body:", await e.response.text());
    } else {
        console.error("Unexpected error:", e);
    }
}

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Runtime requirements

• Node.js with global fetch (Node 18+ recommended).
• TypeScript target: ES2020 works.

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Security notes

• Keep your VAPID private key secret.
• Always validate subscriptions server-side before storing or using them.
• Avoid sending sensitive data in payloads; push payloads can be stored/forwarded by push services.

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License

Apache 2.0 See LICENSE