Official HelloJohn SDKs for React, JavaScript, Next.js, Node.js, Go, and Python — with TypeScript support throughout.

SDKs

HelloJohn provides official SDKs for the most common languages and frameworks. All SDKs are open source, typed, and follow the same design principles: sensible defaults, minimal configuration, and full flexibility when you need it.

Available SDKs

SDK	Package	Use case
React	`@hellojohn/react`	React apps (hooks + components)
JavaScript	`@hellojohn/js`	Vanilla JS, Vue, Svelte, Angular
Next.js	`@hellojohn/nextjs`	Next.js App Router + Pages Router
Node.js	`@hellojohn/node`	Backend services, admin operations
Go	`github.com/hellojohn/hellojohn-go`	Go servers and services
Python	`hellojohn`	Python backends (FastAPI, Django, Flask)

Client vs. server SDKs

HelloJohn SDKs come in two flavors:

Client SDKs (React, JS, Next.js client components):

Run in the browser
Use the publishable key (pk_...)
Handle sign-in, sign-up, session management, MFA
Cannot access admin operations

Server SDKs (Node.js, Go, Python, Next.js server):

Run on your backend
Use the secret key (sk_...)
Can manage users, tenants, sessions
Never expose the secret key to browsers

// ✅ Client: use publishable key
const hj = createHelloJohnClient({ publishableKey: 'pk_live_...' });

// ✅ Server: use secret key
const hj = createHelloJohnAdminClient({ secretKey: process.env.HJ_SECRET_KEY });

Key types

Key	Prefix	Where used	Capabilities
Publishable key	`pk_live_` or `pk_test_`	Client-side code	Auth flows only
Secret key	`sk_live_` or `sk_test_`	Server-side only	Full admin API

Find your keys in the HelloJohn dashboard under Settings → API Keys.

Common patterns

Verify a JWT in your backend

Every server SDK provides a verifyToken helper:

// Node.js
import { verifyToken } from '@hellojohn/node';

const payload = await verifyToken(accessToken, {
  secretKey: process.env.HJ_SECRET_KEY,
});
// payload.sub — user ID
// payload.tenant_id — tenant
// payload.role — user's role

// Go
payload, err := hj.VerifyToken(ctx, accessToken)
if err != nil {
    http.Error(w, "Unauthorized", http.StatusUnauthorized)
    return
}

# Python
payload = hj.verify_token(access_token)

Protect a route

// Next.js middleware
import { withHelloJohnAuth } from '@hellojohn/nextjs/server';

export default withHelloJohnAuth(async (req) => {
  const user = req.auth.user;
  // ...
});

// Go middleware
func AuthMiddleware(hj *hellojohn.Client) func(http.Handler) http.Handler {
    return func(next http.Handler) http.Handler {
        return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
            token := r.Header.Get("Authorization")
            payload, err := hj.VerifyToken(r.Context(), strings.TrimPrefix(token, "Bearer "))
            if err != nil {
                http.Error(w, "Unauthorized", 401)
                return
            }
            ctx := context.WithValue(r.Context(), "user", payload)
            next.ServeHTTP(w, r.WithContext(ctx))
        })
    }
}

SDK versioning

All SDKs follow Semantic Versioning. SDK minor and patch versions are compatible with the same HelloJohn server version range:

SDK version	Compatible server versions
1.x.x	HelloJohn 1.x.x
2.x.x	HelloJohn 2.x.x

Community SDKs

Community-maintained SDKs (not officially supported):

Ruby — github.com/hellojohn-community/hellojohn-ruby
PHP — github.com/hellojohn-community/hellojohn-php
Java — github.com/hellojohn-community/hellojohn-java
Rust — github.com/hellojohn-community/hellojohn-rs

Want to build an SDK for another language? See our SDK Development Guide.

Getting help

GitHub Issues — Bug reports and feature requests
Discord — Community support
support@hellojohn.dev — Enterprise support

SDKs

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