SvelteKit Integration

Before you start, make sure you have a Better Auth instance configured. If you haven't done that yet, check out the installation.

Mount the handler

We need to mount the handler to SvelteKit server hook.

hooks.server.ts
import { auth } from "$lib/auth";
import { svelteKitHandler } from "better-auth/svelte-kit";
import { building } from "$app/environment";
 
export async function handle({ event, resolve }) {
  return svelteKitHandler({ event, resolve, auth, building });
}

Server Action Cookies

To ensure cookies are properly set when you call functions like signInEmail or signUpEmail in a server action, you should use the sveltekitCookies plugin. This plugin will automatically handle setting cookies for you in SvelteKit.

You need to add it as a plugin to your Better Auth instance.

The getRequestEvent function is available in SvelteKit 2.2.0 and later. Make sure you are using a compatible version.

lib/auth.ts
import { betterAuth } from "better-auth";
import { sveltekitCookies } from "better-auth/svelte-kit";
import { getRequestEvent } from "$app/server";
 
export const auth = betterAuth({
  // ... your config
  plugins: [sveltekitCookies(getRequestEvent)],
});

Create a client

Create a client instance. You can name the file anything you want. Here we are creating client.ts file inside the lib/ directory.

auth-client.ts
import { createAuthClient } from "better-auth/svelte"; // make sure to import from better-auth/svelte
 
export const authClient = createAuthClient({
  // you can pass client configuration here
});

Once you have created the client, you can use it to sign up, sign in, and perform other actions. Some of the actions are reactive. The client use nano-store to store the state and reflect changes when there is a change like a user signing in or out affecting the session state.

Example usage

<script lang="ts">
  import { authClient } from "$lib/client";
  const session = authClient.useSession();
</script>
    <div>
      {#if $session.data}
        <div>
          <p>
            {$session?.data?.user.name}
          </p>
          <button
            on:click={async () => {
              await authClient.signOut();
            }}
          >
            Sign Out
          </button>
        </div>
      {:else}
        <button
          on:click={async () => {
            await authClient.signIn.social({
              provider: "github",
            });
          }}
        >
          Continue with GitHub
        </button>
      {/if}
    </div>

Nuxt Integration

Integrate Better Auth with Nuxt.

SolidStart Integration

Integrate Better Auth with SolidStart.

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