diff --git a/apps/web/src/__tests__/lib/horizonAccount.test.ts b/apps/web/src/__tests__/lib/horizonAccount.test.ts
new file mode 100644
index 00000000..7aaeb679
--- /dev/null
+++ b/apps/web/src/__tests__/lib/horizonAccount.test.ts
@@ -0,0 +1,53 @@
+import { describe, it, expect, beforeEach, afterEach, vi } from "vitest";
+
+import { fetchBalances, horizonUrlFor } from "../../lib/horizonAccount";
+
+const PUBLIC_KEY = "GBBD47IF6LWK7P7MDEVSCWR7DPUWV3NY3DTQEVFL4NAT4AQH3ZLLFLA5";
+
+describe("horizonUrlFor", () => {
+  it("returns the Horizon mainnet URL for \"mainnet\"", () => {
+    expect(horizonUrlFor("mainnet")).toBe("https://horizon.stellar.org");
+  });
+
+  it("returns the Horizon testnet URL for any other value", () => {
+    expect(horizonUrlFor("testnet")).toBe(
+      "https://horizon-testnet.stellar.org"
+    );
+    expect(horizonUrlFor("futurenet")).toBe(
+      "https://horizon-testnet.stellar.org"
+    );
+  });
+});
+
+describe("fetchBalances", () => {
+  beforeEach(() => {
+    vi.stubGlobal("fetch", vi.fn());
+  });
+
+  afterEach(() => {
+    vi.unstubAllGlobals();
+  });
+
+  it("resolves to null when the Horizon response isn't ok", async () => {
+    vi.mocked(fetch).mockResolvedValue({ ok: false } as Response);
+
+    await expect(fetchBalances(PUBLIC_KEY, "testnet")).resolves.toBeNull();
+  });
+
+  it("resolves to the parsed balances on a successful response", async () => {
+    const balances = [
+      { asset_type: "native", balance: "100.0000000" },
+    ];
+    vi.mocked(fetch).mockResolvedValue({
+      ok: true,
+      json: async () => ({ balances }),
+    } as Response);
+
+    await expect(fetchBalances(PUBLIC_KEY, "mainnet")).resolves.toEqual({
+      balances,
+    });
+    expect(fetch).toHaveBeenCalledWith(
+      `https://horizon.stellar.org/accounts/${PUBLIC_KEY}`
+    );
+  });
+});