diff --git a/src/actions/voucher.test.ts b/src/actions/voucher.test.ts
new file mode 100644
index 00000000..dcdd5ca7
--- /dev/null
+++ b/src/actions/voucher.test.ts
@@ -0,0 +1,161 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+vi.mock("next/server", () => ({
+	NextResponse: {
+		json: vi.fn(),
+	},
+}));
+
+vi.mock("next-auth", () => ({
+	default: vi.fn(() => ({
+		handlers: {},
+		auth: vi.fn(),
+		signOut: vi.fn(),
+	})),
+}));
+
+vi.mock("@/lib/auth", () => ({
+	auth: vi.fn(),
+	handlers: {},
+	signOut: vi.fn(),
+}));
+
+const mockAuth = vi.hoisted(() => vi.fn());
+vi.mock("@/lib/auth", () => ({
+	auth: mockAuth,
+}));
+
+const hoistedInsertValues = vi.hoisted(() => vi.fn());
+const hoistedDeleteWhere = vi.hoisted(() => vi.fn());
+const hoistedSelectLimit = vi.hoisted(() => vi.fn());
+const hoistedSelectWhere = vi.hoisted(() =>
+	vi.fn(() => ({ limit: hoistedSelectLimit })),
+);
+const hoistedSelectFrom = vi.hoisted(() =>
+	vi.fn(() => ({ where: hoistedSelectWhere })),
+);
+const hoistedUpdateWhere = vi.hoisted(() => vi.fn());
+const hoistedUpdateSetObj = vi.hoisted(() => ({
+	set: vi.fn(() => ({ where: hoistedUpdateWhere })),
+}));
+
+vi.mock("@/lib/db", () => ({
+	db: {
+		select: vi.fn(() => ({ from: hoistedSelectFrom })),
+		insert: vi.fn(() => ({ values: hoistedInsertValues })),
+		update: vi.fn(() => hoistedUpdateSetObj),
+		delete: vi.fn(() => ({ where: hoistedDeleteWhere })),
+	},
+	WebsiteShopVouchers: {
+		id: "voucher.id",
+		code: "voucher.code",
+		amount: "voucher.amount",
+		maxUses: "voucher.maxUses",
+		useCount: "voucher.useCount",
+		expiresAt: "voucher.expiresAt",
+	},
+	WebsiteUsedShopVouchers: {
+		id: "used.id",
+		userId: "used.userId",
+		voucherId: "used.voucherId",
+	},
+}));
+
+const mockSendCurrency = vi.hoisted(() => vi.fn());
+vi.mock("@/lib/services/send-currency", () => ({
+	currencyDb: {},
+	sendCurrency: mockSendCurrency,
+}));
+
+const mockRateLimit = vi.hoisted(() => vi.fn());
+vi.mock("@/lib/rate-limit", () => ({
+	clientIp: vi.fn().mockResolvedValue("127.0.0.1"),
+	rateLimit: mockRateLimit,
+}));
+
+const mockRevalidatePath = vi.hoisted(() => vi.fn());
+vi.mock("next/cache", () => ({
+	revalidatePath: mockRevalidatePath,
+	unstable_cache: (fn: any) => fn,
+}));
+
+import { db } from "@/lib/db";
+import { redeem } from "./voucher";
+
+const fakeForm = (data: Record<string, string>) =>
+	({
+		get: (key: string) => data[key] ?? null,
+	}) as unknown as FormData;
+
+beforeEach(() => {
+	vi.clearAllMocks();
+	mockAuth.mockResolvedValue({ user: { id: "1" } });
+	mockRateLimit.mockResolvedValue({ ok: true });
+	hoistedSelectLimit.mockResolvedValue([]);
+	hoistedInsertValues.mockResolvedValue([]);
+	hoistedUpdateWhere.mockResolvedValue([]);
+	mockSendCurrency.mockResolvedValue(undefined);
+});
+
+describe("redeem action", () => {
+	it("rejects if user is not signed in", async () => {
+		mockAuth.mockResolvedValueOnce(null);
+		const result = await redeem(null, fakeForm({ code: "TEST" }));
+		expect(result).toEqual({
+			ok: false,
+			message: "You must be signed in to redeem a voucher.",
+		});
+	});
+
+	it("rejects if rate limited", async () => {
+		mockRateLimit.mockResolvedValueOnce({ ok: false });
+		const result = await redeem(null, fakeForm({ code: "TEST" }));
+		expect(result?.ok).toBe(false);
+		expect(result?.message).toContain("too fast");
+	});
+
+	it("rejects empty codes", async () => {
+		const result = await redeem(null, fakeForm({ code: "" }));
+		expect(result).toEqual({
+			ok: false,
+			message: "Please enter a voucher code.",
+		});
+	});
+
+	it("rejects if voucher does not exist or is expired", async () => {
+		hoistedSelectLimit.mockResolvedValueOnce([]); // voucher query
+		const result = await redeem(null, fakeForm({ code: "INVALID" }));
+		expect(result).toEqual({
+			ok: false,
+			message: "No active voucher with the given code was found.",
+		});
+	});
+
+	it("successfully redeems a valid voucher", async () => {
+		const futureDate = new Date(Date.now() + 86400000);
+		// 1st call: voucher query, 2nd call: already used check, 3rd & 4th calls: bump useCount / check maxUses
+		hoistedSelectLimit
+			.mockResolvedValueOnce([
+				{
+					id: 10n,
+					amount: 500,
+					maxUses: 10,
+					useCount: 2,
+					expiresAt: futureDate,
+				},
+			])
+			.mockResolvedValueOnce([]) // not used yet
+			.mockResolvedValueOnce([{ maxUses: 10, useCount: 3 }]); // updated count
+
+		const result = await redeem(null, fakeForm({ code: "VALIDCODE" }));
+		expect(result?.ok).toBe(true);
+		expect(result?.message).toContain("500 credits");
+		expect(mockSendCurrency).toHaveBeenCalledWith(
+			expect.any(Object),
+			1,
+			"credits",
+			500,
+		);
+		expect(db.insert).toHaveBeenCalled();
+	});
+});