diff --git a/src/app.ts b/src/app.ts
index 330c05b..3cf7858 100644
--- a/src/app.ts
+++ b/src/app.ts
@@ -68,6 +68,7 @@ import {
   navigateSettings,
   selectSettingsItem,
   goBackInSettings,
+  getSelectedProviderUrl,
   type SettingsState,
 } from "./components/SettingsPanel";
 
@@ -363,6 +364,15 @@ export class HackerNewsApp {
     } else if (key.name === "k" || key.name === "up") {
       navigateSettings(this.settingsState, -1, getConfiguredProvider() || "anthropic");
       this.rerenderSettings();
+    } else if (key.name === "tab") {
+      // Open API key URL if a provider without a key is selected
+      const url = getSelectedProviderUrl(
+        this.settingsState,
+        getConfiguredProvider() || "anthropic",
+      );
+      if (url) {
+        this.callbacks.onOpenUrl?.(url);
+      }
     } else if (key.name === "return" || key.name === "enter") {
       const action = selectSettingsItem(
         this.settingsState,
diff --git a/src/components/SettingsPanel.ts b/src/components/SettingsPanel.ts
index 57155ca..e5cb12e 100644
--- a/src/components/SettingsPanel.ts
+++ b/src/components/SettingsPanel.ts
@@ -8,6 +8,17 @@ import {
   OPENAI_MODELS,
 } from "../config";
 
+const PROVIDER_API_KEY_URLS: Record<Provider, { display: string; full: string }> = {
+  anthropic: {
+    display: "platform.claude.com",
+    full: "https://platform.claude.com/settings/keys",
+  },
+  openai: {
+    display: "platform.openai.com",
+    full: "https://platform.openai.com/api-keys",
+  },
+};
+
 type SettingsItemType =
   | { type: "provider"; provider: Provider; hasKey: boolean }
   | { type: "model"; modelId: string; modelName: string }
@@ -139,8 +150,8 @@ export function renderSettings(
 
     if (!hasKey) {
       const hint = new TextRenderable(ctx, {
-        content: "Add API Key",
-        fg: COLORS.textSecondary,
+        content: `${PROVIDER_API_KEY_URLS[listItem.item.provider].display} (tab)`,
+        fg: COLORS.textTertiary,
       });
       itemBox.add(hint);
     }
@@ -305,3 +316,22 @@ export function selectSettingsItem(
 export function goBackInSettings(_state: SettingsState): boolean {
   return false; // Always exit settings on Esc
 }
+
+/**
+ * Returns the API key URL for the currently selected provider if it doesn't have a key.
+ * Returns null if the selection is not a provider or if the provider already has a key.
+ */
+export function getSelectedProviderUrl(
+  state: SettingsState,
+  chatProvider: Provider,
+): string | null {
+  const items = getSettingsList(chatProvider);
+  const selected = items[state.selectedIndex];
+  if (!selected) return null;
+
+  if (selected.item.type === "provider" && !selected.item.hasKey) {
+    return PROVIDER_API_KEY_URLS[selected.item.provider].full;
+  }
+
+  return null;
+}
diff --git a/src/test/settings.test.ts b/src/test/settings.test.ts
index 0196c41..7b7e116 100644
--- a/src/test/settings.test.ts
+++ b/src/test/settings.test.ts
@@ -1,4 +1,6 @@
 import { describe, it, expect } from "bun:test";
+import { getSelectedProviderUrl, initSettingsState, type SettingsState } from "../components/SettingsPanel";
+import { getApiKey } from "../config";
 
 // NOTE: Settings Mode rendering tests are skipped due to a pre-existing Yoga layout engine crash
 // in the OpenTUI test framework. The settings action logic is tested by directly calling
@@ -289,3 +291,61 @@ describe("Auth Setup State Management", () => {
     expect(mockState.keyInput).toBeNull();
   });
 });
+
+describe("Provider API Key URLs", () => {
+  it("should return correct Anthropic URL when Anthropic has no key and is selected", () => {
+    // Only test if Anthropic doesn't have a key configured
+    if (getApiKey("anthropic")) return;
+
+    const state = initSettingsState();
+    state.selectedIndex = 0; // Anthropic is first in the list
+
+    const url = getSelectedProviderUrl(state, "anthropic");
+    expect(url).toBe("https://platform.claude.com/settings/keys");
+  });
+
+  it("should return correct OpenAI URL when OpenAI has no key and is selected", () => {
+    // Only test if OpenAI doesn't have a key configured
+    if (getApiKey("openai")) return;
+
+    const state = initSettingsState();
+    state.selectedIndex = 1; // OpenAI is second in the list
+
+    const url = getSelectedProviderUrl(state, "anthropic");
+    expect(url).toBe("https://platform.openai.com/api-keys");
+  });
+
+  it("should return null when selection is not a provider (action item)", () => {
+    const state = initSettingsState();
+    // Done action is at index 2 when no keys are configured
+    state.selectedIndex = 2;
+
+    const url = getSelectedProviderUrl(state, "anthropic");
+    expect(url).toBeNull();
+  });
+
+  it("should return null when selected index is out of bounds", () => {
+    const state = initSettingsState();
+    state.selectedIndex = 999;
+
+    const url = getSelectedProviderUrl(state, "anthropic");
+    expect(url).toBeNull();
+  });
+
+  it("should return null when provider has a key configured", () => {
+    // This test verifies the behavior when a provider already has a key
+    // We can't easily mock this, but we can verify the function exists
+    // and handles the case based on real config state
+    const state = initSettingsState();
+    state.selectedIndex = 0;
+
+    const url = getSelectedProviderUrl(state, "anthropic");
+
+    // If Anthropic has a key, URL should be null; otherwise it should be the Anthropic URL
+    if (getApiKey("anthropic")) {
+      expect(url).toBeNull();
+    } else {
+      expect(url).toBe("https://platform.claude.com/settings/keys");
+    }
+  });
+});