diff --git a/tests/AltumClientTest.php b/tests/AltumClientTest.php
new file mode 100644
index 0000000..03ed10a
--- /dev/null
+++ b/tests/AltumClientTest.php
@@ -0,0 +1,181 @@
+<?php
+
+declare(strict_types=1);
+
+use Core\Plug\Altum\AltumClient;
+use Illuminate\Support\Facades\Http;
+
+beforeEach(function () {
+    $this->client = new AltumClient(
+        baseUrl: 'https://test.example.com',
+        adminApiKey: 'test-admin-key',
+        userApiKey: 'test-user-key',
+    );
+});
+
+it('builds correct user API GET URL', function () {
+    Http::fake([
+        'test.example.com/api/user' => Http::response(['data' => ['id' => 1]], 200),
+    ]);
+
+    $result = $this->client->user();
+
+    expect($result)->toHaveKey('data');
+    expect($result['data']['id'])->toBe(1);
+});
+
+it('lists resources with pagination params', function () {
+    Http::fake([
+        'test.example.com/api/websites/*' => Http::response(['data' => []], 200),
+    ]);
+
+    $result = $this->client->listResource('websites', ['page' => 2, 'results_per_page' => 10]);
+
+    expect($result)->toHaveKey('data');
+    Http::assertSent(fn ($request) =>
+        str_contains($request->url(), 'page=2') &&
+        str_contains($request->url(), 'results_per_page=10')
+    );
+});
+
+it('creates resources via POST', function () {
+    Http::fake([
+        'test.example.com/api/links' => Http::response(['data' => ['id' => 42]], 200),
+    ]);
+
+    $result = $this->client->createResource('links', ['url' => 'https://example.com']);
+
+    expect($result['data']['id'])->toBe(42);
+    Http::assertSent(fn ($request) =>
+        $request->method() === 'POST' &&
+        str_contains($request->url(), '/api/links')
+    );
+});
+
+it('updates resources via POST with ID', function () {
+    Http::fake([
+        'test.example.com/api/links/42' => Http::response(['data' => ['id' => 42]], 200),
+    ]);
+
+    $this->client->updateResource('links', 42, ['url' => 'https://new.com']);
+
+    Http::assertSent(fn ($request) =>
+        $request->method() === 'POST' &&
+        str_contains($request->url(), '/api/links/42')
+    );
+});
+
+it('deletes resources', function () {
+    Http::fake([
+        'test.example.com/api/links/42' => Http::response([], 200),
+    ]);
+
+    $this->client->deleteResource('links', 42);
+
+    Http::assertSent(fn ($request) =>
+        $request->method() === 'DELETE' &&
+        str_contains($request->url(), '/api/links/42')
+    );
+});
+
+it('sends Bearer auth for user API', function () {
+    Http::fake(['*' => Http::response([], 200)]);
+
+    $this->client->user();
+
+    Http::assertSent(fn ($request) =>
+        $request->hasHeader('Authorization', 'Bearer test-user-key')
+    );
+});
+
+it('sends Bearer auth for admin API', function () {
+    Http::fake(['*' => Http::response([], 200)]);
+
+    $this->client->listAdminUsers();
+
+    Http::assertSent(fn ($request) =>
+        $request->hasHeader('Authorization', 'Bearer test-admin-key')
+    );
+});
+
+it('throws when user API called without key', function () {
+    $client = new AltumClient(
+        baseUrl: 'https://test.example.com',
+        adminApiKey: 'test-admin-key',
+    );
+
+    $client->user();
+})->throws(\RuntimeException::class, 'User API key not set');
+
+it('returns new instance with withUserKey', function () {
+    $client = new AltumClient(
+        baseUrl: 'https://test.example.com',
+        adminApiKey: 'admin-key',
+    );
+
+    $withKey = $client->withUserKey('new-key');
+
+    expect($withKey)->not->toBe($client);
+
+    Http::fake(['*' => Http::response([], 200)]);
+    $withKey->user();
+
+    Http::assertSent(fn ($request) =>
+        $request->hasHeader('Authorization', 'Bearer new-key')
+    );
+});
+
+it('returns error array on HTTP failure', function () {
+    Http::fake(['*' => Http::response('Unauthorized', 401)]);
+
+    $result = $this->client->user();
+
+    expect($result)->toHaveKey('error', true);
+    expect($result)->toHaveKey('status', 401);
+});
+
+it('returns error array on exception', function () {
+    Http::fake(['*' => fn () => throw new \Exception('Connection refused')]);
+
+    $result = $this->client->user();
+
+    expect($result)->toHaveKey('error', true);
+    expect($result['message'])->toContain('Connection refused');
+});
+
+it('creates user with named params', function () {
+    Http::fake(['*' => Http::response(['data' => ['id' => 5]], 200)]);
+
+    $this->client->createUser('Test User', 'test@example.com', 'secret123');
+
+    Http::assertSent(fn ($request) =>
+        $request->method() === 'POST' &&
+        str_contains($request->url(), '/admin-api/users') &&
+        $request['name'] === 'Test User' &&
+        $request['email'] === 'test@example.com' &&
+        $request['password'] === 'secret123'
+    );
+});
+
+it('assigns VIP plan with correct defaults', function () {
+    Http::fake(['*' => Http::response([], 200)]);
+
+    $this->client->assignVipPlan(5);
+
+    Http::assertSent(fn ($request) =>
+        $request->method() === 'POST' &&
+        str_contains($request->url(), '/admin-api/users/5') &&
+        $request['plan_id'] == 2 &&
+        $request['plan_expiration_date'] === '2056-01-01'
+    );
+});
+
+it('uses form encoding for POST requests', function () {
+    Http::fake(['*' => Http::response([], 200)]);
+
+    $this->client->createResource('links', ['url' => 'https://example.com']);
+
+    Http::assertSent(fn ($request) =>
+        str_contains($request->header('Content-Type')[0] ?? '', 'application/x-www-form-urlencoded')
+    );
+});
diff --git a/tests/AltumManagerTest.php b/tests/AltumManagerTest.php
new file mode 100644
index 0000000..1330d80
--- /dev/null
+++ b/tests/AltumManagerTest.php
@@ -0,0 +1,45 @@
+<?php
+
+declare(strict_types=1);
+
+use Core\Plug\Altum\AltumManager;
+use Core\Plug\Altum\Analytics\Client as AnalyticsClient;
+use Core\Plug\Altum\Biolinks\Client as BiolinksClient;
+use Core\Plug\Altum\Pusher\Client as PusherClient;
+use Core\Plug\Altum\Socialproof\Client as SocialproofClient;
+
+beforeEach(function () {
+    $this->manager = new AltumManager([
+        'analytics' => ['url' => 'https://analytics.test', 'admin_key' => 'akey'],
+        'biolinks' => ['url' => 'https://bio.test', 'admin_key' => 'bkey'],
+        'pusher' => ['url' => 'https://push.test', 'admin_key' => 'pkey'],
+        'socialproof' => ['url' => 'https://trust.test', 'admin_key' => 'skey'],
+    ]);
+});
+
+it('creates analytics client', function () {
+    expect($this->manager->analytics())->toBeInstanceOf(AnalyticsClient::class);
+});
+
+it('creates biolinks client', function () {
+    expect($this->manager->biolinks())->toBeInstanceOf(BiolinksClient::class);
+});
+
+it('creates pusher client', function () {
+    expect($this->manager->pusher())->toBeInstanceOf(PusherClient::class);
+});
+
+it('creates socialproof client', function () {
+    expect($this->manager->socialproof())->toBeInstanceOf(SocialproofClient::class);
+});
+
+it('passes user API key to client', function () {
+    $client = $this->manager->analytics('my-user-key');
+    \Illuminate\Support\Facades\Http::fake(['*' => \Illuminate\Support\Facades\Http::response([], 200)]);
+    $client->user();
+})->throwsNoExceptions();
+
+it('throws on unconfigured product', function () {
+    $mgr = new AltumManager([]);
+    $mgr->analytics();
+})->throws(\RuntimeException::class, 'not configured');
diff --git a/tests/Analytics/ClientTest.php b/tests/Analytics/ClientTest.php
new file mode 100644
index 0000000..573a880
--- /dev/null
+++ b/tests/Analytics/ClientTest.php
@@ -0,0 +1,40 @@
+<?php
+
+declare(strict_types=1);
+
+use Core\Plug\Altum\Analytics\Client;
+use Illuminate\Support\Facades\Http;
+
+beforeEach(function () {
+    $this->client = new Client(
+        baseUrl: 'https://analytics.test',
+        adminApiKey: 'admin-key',
+        userApiKey: 'user-key',
+    );
+    Http::fake(['*' => Http::response(['data' => []], 200)]);
+});
+
+it('lists websites', function () {
+    $this->client->websites();
+    Http::assertSent(fn ($r) => str_contains($r->url(), '/api/websites/'));
+});
+
+it('gets a website', function () {
+    $this->client->website(1);
+    Http::assertSent(fn ($r) => str_contains($r->url(), '/api/websites/1'));
+});
+
+it('creates a website', function () {
+    $this->client->createWebsite(['name' => 'Test', 'host' => 'example.com']);
+    Http::assertSent(fn ($r) => $r->method() === 'POST' && str_contains($r->url(), '/api/websites'));
+});
+
+it('fetches statistics', function () {
+    $this->client->statistics(['website_id' => 1]);
+    Http::assertSent(fn ($r) => str_contains($r->url(), '/api/statistics/'));
+});
+
+it('creates annotations', function () {
+    $this->client->createAnnotation(['website_id' => 1, 'title' => 'Deploy']);
+    Http::assertSent(fn ($r) => str_contains($r->url(), '/api/annotations'));
+});
diff --git a/tests/Biolinks/ClientTest.php b/tests/Biolinks/ClientTest.php
new file mode 100644
index 0000000..659d72e
--- /dev/null
+++ b/tests/Biolinks/ClientTest.php
@@ -0,0 +1,40 @@
+<?php
+
+declare(strict_types=1);
+
+use Core\Plug\Altum\Biolinks\Client;
+use Illuminate\Support\Facades\Http;
+
+beforeEach(function () {
+    $this->client = new Client(
+        baseUrl: 'https://bio.test',
+        adminApiKey: 'admin-key',
+        userApiKey: 'user-key',
+    );
+    Http::fake(['*' => Http::response(['data' => []], 200)]);
+});
+
+it('lists links', function () {
+    $this->client->links();
+    Http::assertSent(fn ($r) => str_contains($r->url(), '/api/links/'));
+});
+
+it('creates a link', function () {
+    $this->client->createLink(['url' => 'https://example.com', 'type' => 'link']);
+    Http::assertSent(fn ($r) => $r->method() === 'POST' && str_contains($r->url(), '/api/links'));
+});
+
+it('gets link statistics', function () {
+    $this->client->linkStatistics(42);
+    Http::assertSent(fn ($r) => str_contains($r->url(), '/api/statistics/42'));
+});
+
+it('lists projects', function () {
+    $this->client->projects();
+    Http::assertSent(fn ($r) => str_contains($r->url(), '/api/projects/'));
+});
+
+it('creates QR codes', function () {
+    $this->client->createQrCode(['name' => 'Test QR', 'link_id' => 1]);
+    Http::assertSent(fn ($r) => $r->method() === 'POST' && str_contains($r->url(), '/api/qr-codes'));
+});
diff --git a/tests/Pest.php b/tests/Pest.php
new file mode 100644
index 0000000..174d7fd
--- /dev/null
+++ b/tests/Pest.php
@@ -0,0 +1,3 @@
+<?php
+
+declare(strict_types=1);
diff --git a/tests/Pusher/ClientTest.php b/tests/Pusher/ClientTest.php
new file mode 100644
index 0000000..cd584e4
--- /dev/null
+++ b/tests/Pusher/ClientTest.php
@@ -0,0 +1,35 @@
+<?php
+
+declare(strict_types=1);
+
+use Core\Plug\Altum\Pusher\Client;
+use Illuminate\Support\Facades\Http;
+
+beforeEach(function () {
+    $this->client = new Client(
+        baseUrl: 'https://push.test',
+        adminApiKey: 'admin-key',
+        userApiKey: 'user-key',
+    );
+    Http::fake(['*' => Http::response(['data' => []], 200)]);
+});
+
+it('lists subscribers', function () {
+    $this->client->subscribers();
+    Http::assertSent(fn ($r) => str_contains($r->url(), '/api/subscribers/'));
+});
+
+it('creates a campaign', function () {
+    $this->client->createCampaign(['title' => 'Test', 'url' => 'https://example.com']);
+    Http::assertSent(fn ($r) => $r->method() === 'POST' && str_contains($r->url(), '/api/campaigns'));
+});
+
+it('lists flows', function () {
+    $this->client->flows();
+    Http::assertSent(fn ($r) => str_contains($r->url(), '/api/flows/'));
+});
+
+it('creates segments', function () {
+    $this->client->createSegment(['name' => 'VIP']);
+    Http::assertSent(fn ($r) => $r->method() === 'POST' && str_contains($r->url(), '/api/segments'));
+});
diff --git a/tests/Socialproof/ClientTest.php b/tests/Socialproof/ClientTest.php
new file mode 100644
index 0000000..244d967
--- /dev/null
+++ b/tests/Socialproof/ClientTest.php
@@ -0,0 +1,35 @@
+<?php
+
+declare(strict_types=1);
+
+use Core\Plug\Altum\Socialproof\Client;
+use Illuminate\Support\Facades\Http;
+
+beforeEach(function () {
+    $this->client = new Client(
+        baseUrl: 'https://trust.test',
+        adminApiKey: 'admin-key',
+        userApiKey: 'user-key',
+    );
+    Http::fake(['*' => Http::response(['data' => []], 200)]);
+});
+
+it('lists campaigns', function () {
+    $this->client->campaigns();
+    Http::assertSent(fn ($r) => str_contains($r->url(), '/api/campaigns/'));
+});
+
+it('creates a campaign', function () {
+    $this->client->createCampaign(['name' => 'Test Campaign', 'type' => 'recent_activity']);
+    Http::assertSent(fn ($r) => $r->method() === 'POST' && str_contains($r->url(), '/api/campaigns'));
+});
+
+it('manages notifications within campaigns', function () {
+    $this->client->createNotification(['campaign_id' => 1, 'title' => 'New sale']);
+    Http::assertSent(fn ($r) => $r->method() === 'POST' && str_contains($r->url(), '/api/notifications'));
+});
+
+it('fetches statistics', function () {
+    $this->client->statistics();
+    Http::assertSent(fn ($r) => str_contains($r->url(), '/api/statistics/'));
+});