diff --git a/e2e/contacts.spec.ts b/e2e/contacts.spec.ts
index 528b10e..0a76574 100644
--- a/e2e/contacts.spec.ts
+++ b/e2e/contacts.spec.ts
@@ -14,23 +14,53 @@ test("shows empty state", async ({ page }) => {
   await expect(page.getByText("No contacts added yet.")).toBeVisible();
 });
 
-test("adds a contact", async ({ page }) => {
+test("adds an email contact and displays it in the list", async ({ page }) => {
   await page.goto("/settings");
   await page.getByPlaceholder("email@example.com").fill("contact@example.com");
   await page.getByRole("button", { name: "Add" }).click();
 
-  await expect(page.getByText("contact@example.com")).toBeVisible();
+  const contactRow = page.getByRole("listitem").filter({ hasText: "contact@example.com" });
+  await expect(contactRow).toBeVisible();
+  await expect(contactRow.getByText("email")).toBeVisible();
+  await expect(contactRow.getByText("contact@example.com")).toBeVisible();
 });
 
-test("removes a contact", async ({ page, adminClient }) => {
-  // Seed a contact
-  await adminClient.from("contacts").insert({ email: "remove-me@example.com" });
+test("adds a Slack contact and displays it in the list", async ({ page }) => {
+  await page.goto("/settings");
+  await page.getByRole("combobox").selectOption("slack");
+  await page.getByPlaceholder("#channel name").fill("#alerts");
+  await page.getByPlaceholder("https://hooks.slack.com/services/...").fill("https://hooks.slack.com/services/T00/B00/test");
+  await page.getByRole("button", { name: "Add" }).click();
+
+  const contactRow = page.getByRole("listitem").filter({ hasText: "#alerts" });
+  await expect(contactRow).toBeVisible();
+  await expect(contactRow.getByText("slack")).toBeVisible();
+  await expect(contactRow.getByText("#alerts")).toBeVisible();
+  await expect(contactRow.getByRole("button", { name: "Remove" })).toBeVisible();
+});
+
+test("removes an email contact", async ({ page, adminClient }) => {
+  await adminClient.from("contacts").insert({ type: "email", email: "remove-me@example.com" });
 
   await page.goto("/settings");
   await expect(page.getByText("remove-me@example.com")).toBeVisible();
 
-  // Click the Remove button next to the specific contact
   const contactRow = page.getByRole("listitem").filter({ hasText: "remove-me@example.com" });
   await contactRow.getByRole("button", { name: "Remove" }).click();
   await expect(page.getByText("remove-me@example.com")).not.toBeVisible();
 });
+
+test("removes a Slack contact", async ({ page, adminClient }) => {
+  await adminClient.from("contacts").insert({
+    type: "slack",
+    webhook_url: "https://hooks.slack.com/services/T00/B00/remove-test",
+    label: "#ops-alerts",
+  });
+
+  await page.goto("/settings");
+  const contactRow = page.getByRole("listitem").filter({ hasText: "#ops-alerts" });
+  await expect(contactRow).toBeVisible();
+
+  await contactRow.getByRole("button", { name: "Remove" }).click();
+  await expect(page.getByText("#ops-alerts")).not.toBeVisible();
+});
diff --git a/src/__tests__/check-runner.test.ts b/src/__tests__/check-runner.test.ts
index 88187b2..ad14c68 100644
--- a/src/__tests__/check-runner.test.ts
+++ b/src/__tests__/check-runner.test.ts
@@ -11,9 +11,11 @@ vi.mock('@/lib/checker', async (importOriginal) => {
 })
 
 // Mock the notifications module
-const mockSendIncidentAlert = vi.fn()
+const mockSendIncidentEmail = vi.fn()
+const mockSendIncidentSlack = vi.fn()
 vi.mock('@/lib/notifications', () => ({
-  sendIncidentAlert: (...args: unknown[]) => mockSendIncidentAlert(...args),
+  sendIncidentEmail: (...args: unknown[]) => mockSendIncidentEmail(...args),
+  sendIncidentSlack: (...args: unknown[]) => mockSendIncidentSlack(...args),
 }))
 
 // Mock the admin client
@@ -30,7 +32,8 @@ import { checkSite } from '@/lib/checker'
 describe('POST /api/checks/run', () => {
   beforeEach(() => {
     vi.clearAllMocks()
-    mockSendIncidentAlert.mockResolvedValue(undefined)
+    mockSendIncidentEmail.mockResolvedValue(undefined)
+    mockSendIncidentSlack.mockResolvedValue(undefined)
     process.env.CRON_SECRET = 'test-secret'
   })
 
@@ -90,7 +93,7 @@ describe('POST /api/checks/run', () => {
     expect(body).toEqual({ message: 'No sites to check', checks: 0, incidents: 0 })
   })
 
-  test('hard failure (HTTP 500) creates incident immediately, sends email', async () => {
+  test('hard failure creates incident, sends email and Slack alerts', async () => {
     const site = { id: 'site-1', name: 'Test', url: 'https://example.com' }
 
     mockFrom.mockImplementation((table: string) => {
@@ -129,7 +132,10 @@ describe('POST /api/checks/run', () => {
       if (table === 'contacts') {
         return {
           select: () => ({
-            data: [{ email: 'alice@example.com' }],
+            data: [
+              { type: 'email', email: 'alice@example.com', webhook_url: null },
+              { type: 'slack', email: null, webhook_url: 'https://hooks.slack.com/services/T00/B00/xxx' },
+            ],
           }),
         }
       }
@@ -151,13 +157,20 @@ describe('POST /api/checks/run', () => {
     const body = await response.json()
     expect(body.checks).toBe(1)
     expect(body.incidents).toBe(1)
-    expect(mockSendIncidentAlert).toHaveBeenCalledWith({
+    expect(mockSendIncidentEmail).toHaveBeenCalledWith({
       siteName: 'Test',
       siteUrl: 'https://example.com',
       error: 'HTTP 500',
       incidentId: 'inc-1',
       contactEmails: ['alice@example.com'],
     })
+    expect(mockSendIncidentSlack).toHaveBeenCalledWith({
+      siteName: 'Test',
+      siteUrl: 'https://example.com',
+      error: 'HTTP 500',
+      incidentId: 'inc-1',
+      webhookUrls: ['https://hooks.slack.com/services/T00/B00/xxx'],
+    })
   })
 
   test('single soft failure (HTTP 503) does not create incident', async () => {
@@ -217,7 +230,8 @@ describe('POST /api/checks/run', () => {
     const response = await POST(request)
     const body = await response.json()
     expect(body.incidents).toBe(0)
-    expect(mockSendIncidentAlert).not.toHaveBeenCalled()
+    expect(mockSendIncidentEmail).not.toHaveBeenCalled()
+    expect(mockSendIncidentSlack).not.toHaveBeenCalled()
   })
 
   test('three soft failures within an hour creates incident', async () => {
@@ -272,7 +286,7 @@ describe('POST /api/checks/run', () => {
       if (table === 'contacts') {
         return {
           select: () => ({
-            data: [{ email: 'alice@example.com' }],
+            data: [{ type: 'email', email: 'alice@example.com', webhook_url: null }],
           }),
         }
       }
@@ -293,7 +307,8 @@ describe('POST /api/checks/run', () => {
     const response = await POST(request)
     const body = await response.json()
     expect(body.incidents).toBe(1)
-    expect(mockSendIncidentAlert).toHaveBeenCalled()
+    expect(mockSendIncidentEmail).toHaveBeenCalled()
+    expect(mockSendIncidentSlack).toHaveBeenCalled()
   })
 
   test('two soft failures within an hour does not create incident', async () => {
@@ -356,7 +371,8 @@ describe('POST /api/checks/run', () => {
     const response = await POST(request)
     const body = await response.json()
     expect(body.incidents).toBe(0)
-    expect(mockSendIncidentAlert).not.toHaveBeenCalled()
+    expect(mockSendIncidentEmail).not.toHaveBeenCalled()
+    expect(mockSendIncidentSlack).not.toHaveBeenCalled()
   })
 
   test('records checks without creating incidents for successful checks', async () => {
@@ -397,7 +413,8 @@ describe('POST /api/checks/run', () => {
     expect(mockInsert).toHaveBeenCalledWith(
       expect.objectContaining({ status: 'success', status_code: 200 })
     )
-    expect(mockSendIncidentAlert).not.toHaveBeenCalled()
+    expect(mockSendIncidentEmail).not.toHaveBeenCalled()
+    expect(mockSendIncidentSlack).not.toHaveBeenCalled()
   })
 
   test('skips rejected promises from Promise.allSettled', async () => {
@@ -441,7 +458,7 @@ describe('POST /api/checks/run', () => {
     expect(body.incidents).toBe(0)
   })
 
-  test('does not send email for existing open incident', async () => {
+  test('does not send alerts for existing open incident', async () => {
     const site = { id: 'site-1', name: 'Test', url: 'https://example.com' }
 
     mockFrom.mockImplementation((table: string) => {
@@ -489,7 +506,8 @@ describe('POST /api/checks/run', () => {
     const response = await POST(request)
     const body = await response.json()
     expect(body.incidents).toBe(0)
-    expect(mockSendIncidentAlert).not.toHaveBeenCalled()
+    expect(mockSendIncidentEmail).not.toHaveBeenCalled()
+    expect(mockSendIncidentSlack).not.toHaveBeenCalled()
   })
 })
 
diff --git a/src/__tests__/contacts.test.ts b/src/__tests__/contacts.test.ts
index e746a66..28b6cc2 100644
--- a/src/__tests__/contacts.test.ts
+++ b/src/__tests__/contacts.test.ts
@@ -37,12 +37,12 @@ describe("addContact action", () => {
     mockGetUser.mockResolvedValue({ data: { user: null } })
 
     const formData = new FormData()
-    formData.set("email", "test@example.com")
+    formData.set("contact_email", "test@example.com")
 
     await expect(addContact(formData)).rejects.toThrow("NEXT_REDIRECT:/login")
   })
 
-  test("inserts contact for authenticated users", async () => {
+  test("inserts email contact for authenticated users", async () => {
     mockGetUser.mockResolvedValue({
       data: { user: { id: "user-1" } },
     })
@@ -51,11 +51,47 @@ describe("addContact action", () => {
     mockFrom.mockReturnValue({ insert: mockInsert })
 
     const formData = new FormData()
-    formData.set("email", "test@example.com")
+    formData.set("contact_type", "email")
+    formData.set("contact_email", "test@example.com")
 
     await addContact(formData)
     expect(mockFrom).toHaveBeenCalledWith("contacts")
-    expect(mockInsert).toHaveBeenCalledWith({ email: "test@example.com" })
+    expect(mockInsert).toHaveBeenCalledWith({ type: "email", email: "test@example.com" })
+  })
+
+  test("inserts Slack contact for authenticated users", async () => {
+    mockGetUser.mockResolvedValue({
+      data: { user: { id: "user-1" } },
+    })
+
+    const mockInsert = vi.fn().mockReturnValue({ error: null })
+    mockFrom.mockReturnValue({ insert: mockInsert })
+
+    const formData = new FormData()
+    formData.set("contact_type", "slack")
+    formData.set("contact_label", "#alerts")
+    formData.set("contact_webhook_url", "https://hooks.slack.com/services/T00/B00/xxx")
+
+    await addContact(formData)
+    expect(mockFrom).toHaveBeenCalledWith("contacts")
+    expect(mockInsert).toHaveBeenCalledWith({
+      type: "slack",
+      webhook_url: "https://hooks.slack.com/services/T00/B00/xxx",
+      label: "#alerts",
+    })
+  })
+
+  test("rejects invalid Slack webhook URL", async () => {
+    mockGetUser.mockResolvedValue({
+      data: { user: { id: "user-1" } },
+    })
+
+    const formData = new FormData()
+    formData.set("contact_type", "slack")
+    formData.set("contact_webhook_url", "https://example.com/not-slack")
+
+    await addContact(formData)
+    expect(mockFrom).not.toHaveBeenCalled()
   })
 
   test("does nothing if email is empty", async () => {
@@ -64,9 +100,49 @@ describe("addContact action", () => {
     })
 
     const formData = new FormData()
+    formData.set("contact_type", "email")
+    await addContact(formData)
+    expect(mockFrom).not.toHaveBeenCalled()
+  })
+
+  test("does nothing if webhook URL is empty for Slack", async () => {
+    mockGetUser.mockResolvedValue({
+      data: { user: { id: "user-1" } },
+    })
+
+    const formData = new FormData()
+    formData.set("contact_type", "slack")
+    formData.set("contact_label", "#alerts")
     await addContact(formData)
     expect(mockFrom).not.toHaveBeenCalled()
   })
+
+  test("does nothing if label is empty for Slack", async () => {
+    mockGetUser.mockResolvedValue({
+      data: { user: { id: "user-1" } },
+    })
+
+    const formData = new FormData()
+    formData.set("contact_type", "slack")
+    formData.set("contact_webhook_url", "https://hooks.slack.com/services/T00/B00/xxx")
+    await addContact(formData)
+    expect(mockFrom).not.toHaveBeenCalled()
+  })
+
+  test("defaults to email type when contact_type is not set", async () => {
+    mockGetUser.mockResolvedValue({
+      data: { user: { id: "user-1" } },
+    })
+
+    const mockInsert = vi.fn().mockReturnValue({ error: null })
+    mockFrom.mockReturnValue({ insert: mockInsert })
+
+    const formData = new FormData()
+    formData.set("contact_email", "test@example.com")
+
+    await addContact(formData)
+    expect(mockInsert).toHaveBeenCalledWith({ type: "email", email: "test@example.com" })
+  })
 })
 
 describe("deleteContact action", () => {
diff --git a/src/__tests__/notifications.test.ts b/src/__tests__/notifications.test.ts
index 81e36f7..4a174b8 100644
--- a/src/__tests__/notifications.test.ts
+++ b/src/__tests__/notifications.test.ts
@@ -8,16 +8,20 @@ vi.mock("resend", () => ({
   },
 }))
 
-import { sendIncidentAlert } from "@/lib/notifications"
+// Mock fetch for Slack
+const mockFetch = vi.fn()
+vi.stubGlobal("fetch", mockFetch)
 
-describe("sendIncidentAlert", () => {
+import { sendIncidentEmail, sendIncidentSlack } from "@/lib/notifications"
+
+describe("sendIncidentEmail", () => {
   beforeEach(() => {
     vi.clearAllMocks()
     mockSend.mockResolvedValue({ id: "email-1" })
   })
 
   test("sends email to all contacts with correct content", async () => {
-    await sendIncidentAlert({
+    await sendIncidentEmail({
       siteName: "Main Website",
       siteUrl: "https://example.com",
       error: "HTTP 503",
@@ -37,7 +41,7 @@ describe("sendIncidentAlert", () => {
   })
 
   test("does nothing when contactEmails is empty", async () => {
-    await sendIncidentAlert({
+    await sendIncidentEmail({
       siteName: "Main Website",
       siteUrl: "https://example.com",
       error: "HTTP 503",
@@ -52,7 +56,7 @@ describe("sendIncidentAlert", () => {
     const consoleSpy = vi.spyOn(console, "error").mockImplementation(() => {})
     mockSend.mockRejectedValue(new Error("API rate limit"))
 
-    await sendIncidentAlert({
+    await sendIncidentEmail({
       siteName: "Main Website",
       siteUrl: "https://example.com",
       error: "HTTP 503",
@@ -68,7 +72,7 @@ describe("sendIncidentAlert", () => {
   })
 
   test("works without error field", async () => {
-    await sendIncidentAlert({
+    await sendIncidentEmail({
       siteName: "Main Website",
       siteUrl: "https://example.com",
       error: null,
@@ -80,3 +84,120 @@ describe("sendIncidentAlert", () => {
     expect(call.html).not.toContain("<strong>Error:</strong>")
   })
 })
+
+describe("sendIncidentSlack", () => {
+  beforeEach(() => {
+    vi.clearAllMocks()
+  })
+
+  test("posts to all Slack webhooks with correct content", async () => {
+    mockFetch.mockResolvedValue({ ok: true })
+
+    await sendIncidentSlack({
+      siteName: "Main Website",
+      siteUrl: "https://example.com",
+      error: "HTTP 503",
+      incidentId: "inc-1",
+      webhookUrls: ["https://hooks.slack.com/services/T00/B00/xxx"],
+    })
+
+    expect(mockFetch).toHaveBeenCalledTimes(1)
+    const [url, options] = mockFetch.mock.calls[0]
+    expect(url).toBe("https://hooks.slack.com/services/T00/B00/xxx")
+    expect(options.method).toBe("POST")
+
+    const body = JSON.parse(options.body)
+    expect(body.text).toContain("Site status alert: new incident")
+    expect(body.text).toContain("*Main Website* is down")
+    expect(body.text).toContain("https://example.com")
+    expect(body.text).toContain("HTTP 503")
+    expect(body.text).toContain("/incidents/inc-1")
+  })
+
+  test("sends to multiple webhooks", async () => {
+    mockFetch.mockResolvedValue({ ok: true })
+
+    await sendIncidentSlack({
+      siteName: "Main Website",
+      siteUrl: "https://example.com",
+      error: null,
+      incidentId: "inc-1",
+      webhookUrls: [
+        "https://hooks.slack.com/services/T00/B00/aaa",
+        "https://hooks.slack.com/services/T00/B00/bbb",
+      ],
+    })
+
+    expect(mockFetch).toHaveBeenCalledTimes(2)
+    expect(mockFetch.mock.calls[0][0]).toBe("https://hooks.slack.com/services/T00/B00/aaa")
+    expect(mockFetch.mock.calls[1][0]).toBe("https://hooks.slack.com/services/T00/B00/bbb")
+  })
+
+  test("does nothing when webhookUrls is empty", async () => {
+    await sendIncidentSlack({
+      siteName: "Main Website",
+      siteUrl: "https://example.com",
+      error: null,
+      incidentId: "inc-1",
+      webhookUrls: [],
+    })
+
+    expect(mockFetch).not.toHaveBeenCalled()
+  })
+
+  test("handles fetch failure gracefully and continues", async () => {
+    const consoleSpy = vi.spyOn(console, "error").mockImplementation(() => {})
+    mockFetch
+      .mockRejectedValueOnce(new Error("Network error"))
+      .mockResolvedValueOnce({ ok: true })
+
+    await sendIncidentSlack({
+      siteName: "Main Website",
+      siteUrl: "https://example.com",
+      error: null,
+      incidentId: "inc-1",
+      webhookUrls: [
+        "https://hooks.slack.com/services/T00/B00/aaa",
+        "https://hooks.slack.com/services/T00/B00/bbb",
+      ],
+    })
+
+    expect(mockFetch).toHaveBeenCalledTimes(2)
+    expect(consoleSpy).toHaveBeenCalledWith(
+      "Failed to send Slack alert:",
+      expect.any(Error)
+    )
+    consoleSpy.mockRestore()
+  })
+
+  test("logs error when webhook returns non-ok status", async () => {
+    const consoleSpy = vi.spyOn(console, "error").mockImplementation(() => {})
+    mockFetch.mockResolvedValue({ ok: false, status: 403 })
+
+    await sendIncidentSlack({
+      siteName: "Main Website",
+      siteUrl: "https://example.com",
+      error: null,
+      incidentId: "inc-1",
+      webhookUrls: ["https://hooks.slack.com/services/T00/B00/xxx"],
+    })
+
+    expect(consoleSpy).toHaveBeenCalledWith("Slack webhook returned", 403)
+    consoleSpy.mockRestore()
+  })
+
+  test("omits error line when error is null", async () => {
+    mockFetch.mockResolvedValue({ ok: true })
+
+    await sendIncidentSlack({
+      siteName: "Main Website",
+      siteUrl: "https://example.com",
+      error: null,
+      incidentId: "inc-1",
+      webhookUrls: ["https://hooks.slack.com/services/T00/B00/xxx"],
+    })
+
+    const body = JSON.parse(mockFetch.mock.calls[0][1].body)
+    expect(body.text).not.toContain("Error:")
+  })
+})
diff --git a/src/app/api/checks/run/route.ts b/src/app/api/checks/run/route.ts
index d70f136..0355f54 100644
--- a/src/app/api/checks/run/route.ts
+++ b/src/app/api/checks/run/route.ts
@@ -1,7 +1,7 @@
 import { NextRequest, NextResponse } from 'next/server'
 import { createAdminClient } from '@/lib/supabase/admin'
 import { checkSite, isSoftFailure } from '@/lib/checker'
-import { sendIncidentAlert } from '@/lib/notifications'
+import { sendIncidentEmail, sendIncidentSlack } from '@/lib/notifications'
 
 export const maxDuration = 60
 
@@ -95,15 +95,32 @@ async function handleCheckRun(request: NextRequest) {
           if (incident) {
             const { data: contacts } = await supabase
               .from('contacts')
-              .select('email')
-
-            await sendIncidentAlert({
-              siteName: site.name,
-              siteUrl: site.url,
-              error,
-              incidentId: incident.id,
-              contactEmails: (contacts ?? []).map((c: { email: string }) => c.email),
-            })
+              .select('type, email, webhook_url')
+
+            const allContacts = contacts ?? []
+            const emailAddresses = allContacts
+              .filter((c: { type: string }) => c.type === 'email')
+              .map((c: { email: string }) => c.email)
+            const webhookUrls = allContacts
+              .filter((c: { type: string }) => c.type === 'slack')
+              .map((c: { webhook_url: string }) => c.webhook_url)
+
+            await Promise.all([
+              sendIncidentEmail({
+                siteName: site.name,
+                siteUrl: site.url,
+                error,
+                incidentId: incident.id,
+                contactEmails: emailAddresses,
+              }),
+              sendIncidentSlack({
+                siteName: site.name,
+                siteUrl: site.url,
+                error,
+                incidentId: incident.id,
+                webhookUrls,
+              }),
+            ])
           }
         }
       }
diff --git a/src/app/settings/actions.ts b/src/app/settings/actions.ts
index 1fcab26..8953a38 100644
--- a/src/app/settings/actions.ts
+++ b/src/app/settings/actions.ts
@@ -4,6 +4,8 @@ import { revalidatePath } from "next/cache"
 import { redirect } from "next/navigation"
 import { createClient } from "@/lib/supabase/server"
 
+const SLACK_WEBHOOK_REGEX = /^https:\/\/hooks\.slack\.com\/services\/.+$/
+
 export async function addContact(formData: FormData) {
   const supabase = await createClient()
   const {
@@ -12,10 +14,22 @@ export async function addContact(formData: FormData) {
 
   if (!user) redirect("/login")
 
-  const email = formData.get("email") as string
-  if (!email) return
+  const type = (formData.get("contact_type") as string) || "email"
+
+  if (type === "slack") {
+    const webhookUrl = formData.get("contact_webhook_url") as string
+    const label = formData.get("contact_label") as string
+    if (!webhookUrl || !label) return
+    if (!SLACK_WEBHOOK_REGEX.test(webhookUrl)) return
+    const { error } = await supabase.from("contacts").insert({ type: "slack", webhook_url: webhookUrl, label })
+    if (error) console.error("Failed to insert Slack contact:", error)
+  } else {
+    const email = formData.get("contact_email") as string
+    if (!email) return
+    const { error } = await supabase.from("contacts").insert({ type: "email", email })
+    if (error) console.error("Failed to insert email contact:", error)
+  }
 
-  await supabase.from("contacts").insert({ email })
   revalidatePath("/settings")
 }
 
diff --git a/src/app/settings/page.tsx b/src/app/settings/page.tsx
index 332138e..e87ab8c 100644
--- a/src/app/settings/page.tsx
+++ b/src/app/settings/page.tsx
@@ -1,7 +1,8 @@
 import { redirect } from "next/navigation"
 import { createClient } from "@/lib/supabase/server"
 import type { Contact, Invitation } from "@/lib/supabase/types"
-import { addContact, deleteContact } from "./actions"
+import { deleteContact } from "./actions"
+import AddContactForm from "@/components/AddContactForm"
 import { sendInvitation, revokeInvitation } from "./invite-actions"
 import Link from "next/link"
 
@@ -54,7 +55,7 @@ export default async function SettingsPage() {
           Contacts
         </h2>
         <p className="text-sm mb-5" style={{ color: "#5C5C5C" }}>
-          All contacts are notified by email when an incident is opened.
+          All contacts are notified when an incident is opened.
         </p>
 
         <ul className="list-none mb-5">
@@ -69,8 +70,17 @@ export default async function SettingsPage() {
                 className="flex items-center justify-between py-2.5"
                 style={{ borderBottom: "1px solid #F0EDEA" }}
               >
-                <span className="text-[15px]" style={{ color: "#1A1A1A" }}>
-                  {contact.email}
+                <span className="text-[15px] flex items-center gap-2" style={{ color: "#1A1A1A" }}>
+                  <span
+                    className="text-[11px] font-medium uppercase px-1.5 py-0.5 rounded"
+                    style={{
+                      backgroundColor: contact.type === "slack" ? "#E8F0E8" : "#E8EEF4",
+                      color: contact.type === "slack" ? "#2D6A2D" : "#2D4A6A",
+                    }}
+                  >
+                    {contact.type}
+                  </span>
+                  {contact.type === "slack" ? (contact.label || "Slack webhook") : contact.email}
                 </span>
                 <form action={deleteContact.bind(null, contact.id)}>
                   <button
@@ -90,27 +100,7 @@ export default async function SettingsPage() {
           )}
         </ul>
 
-        <form action={addContact} className="flex gap-2">
-          <input
-            type="email"
-            name="email"
-            placeholder="email@example.com"
-            required
-            className="flex-1 text-sm px-3 py-2 rounded outline-none transition-colors"
-            style={{
-              border: "1px solid #E8E4DF",
-              backgroundColor: "#FFFFFF",
-              color: "#1A1A1A",
-            }}
-          />
-          <button
-            type="submit"
-            className="text-sm font-medium px-4 py-2 rounded cursor-pointer text-white"
-            style={{ backgroundColor: "#2C2C2C" }}
-          >
-            Add
-          </button>
-        </form>
+        <AddContactForm />
       </div>
 
       <div
diff --git a/src/components/AddContactForm.tsx b/src/components/AddContactForm.tsx
new file mode 100644
index 0000000..8090d14
--- /dev/null
+++ b/src/components/AddContactForm.tsx
@@ -0,0 +1,74 @@
+"use client"
+
+import { useState } from "react"
+import { addContact } from "@/app/settings/actions"
+
+const inputStyle = {
+  border: "1px solid #E8E4DF",
+  backgroundColor: "#FFFFFF",
+  color: "#1A1A1A",
+}
+
+export default function AddContactForm() {
+  const [type, setType] = useState<"email" | "slack">("email")
+
+  return (
+    <form action={async (formData: FormData) => {
+      await addContact(formData)
+      setType("email")
+    }} className="flex gap-2">
+      <input type="hidden" name="contact_type" value={type} />
+      <select
+        value={type}
+        onChange={(e) => setType(e.target.value as "email" | "slack")}
+        className="text-sm px-2 py-2 rounded"
+        style={inputStyle}
+      >
+        <option value="email">Email</option>
+        <option value="slack">Slack</option>
+      </select>
+      {type === "email" ? (
+        <input
+          type="email"
+          name="contact_email"
+          placeholder="email@example.com"
+          required
+          data-1p-ignore
+          autoComplete="off"
+          className="flex-1 text-sm px-3 py-2 rounded outline-none transition-colors"
+          style={inputStyle}
+        />
+      ) : (
+        <>
+          <input
+            type="text"
+            name="contact_label"
+            placeholder="#channel name"
+            required
+            data-1p-ignore
+            autoComplete="off"
+            className="text-sm px-3 py-2 rounded outline-none transition-colors"
+            style={{ ...inputStyle, width: "140px" }}
+          />
+          <input
+            type="url"
+            name="contact_webhook_url"
+            placeholder="https://hooks.slack.com/services/..."
+            required
+            data-1p-ignore
+            autoComplete="off"
+            className="flex-1 text-sm px-3 py-2 rounded outline-none transition-colors"
+            style={inputStyle}
+          />
+        </>
+      )}
+      <button
+        type="submit"
+        className="text-sm font-medium px-4 py-2 rounded cursor-pointer text-white"
+        style={{ backgroundColor: "#2C2C2C" }}
+      >
+        Add
+      </button>
+    </form>
+  )
+}
diff --git a/src/lib/notifications.ts b/src/lib/notifications.ts
index f528caf..b1d0db4 100644
--- a/src/lib/notifications.ts
+++ b/src/lib/notifications.ts
@@ -6,7 +6,7 @@ function getResend() {
   return _resend
 }
 
-type IncidentAlertParams = {
+type IncidentEmailParams = {
   siteName: string
   siteUrl: string
   error: string | null
@@ -14,13 +14,13 @@ type IncidentAlertParams = {
   contactEmails: string[]
 }
 
-export async function sendIncidentAlert({
+export async function sendIncidentEmail({
   siteName,
   siteUrl,
   error,
   incidentId,
   contactEmails,
-}: IncidentAlertParams) {
+}: IncidentEmailParams) {
   if (contactEmails.length === 0) return
 
   const appUrl = process.env.NEXT_PUBLIC_APP_URL || "https://status.rootsofprogress.org"
@@ -47,3 +47,50 @@ export async function sendIncidentAlert({
     console.error("Failed to send incident alert email:", err)
   }
 }
+
+type IncidentSlackParams = {
+  siteName: string
+  siteUrl: string
+  error: string | null
+  incidentId: string
+  webhookUrls: string[]
+}
+
+export async function sendIncidentSlack({
+  siteName,
+  siteUrl,
+  error,
+  incidentId,
+  webhookUrls,
+}: IncidentSlackParams) {
+  if (webhookUrls.length === 0) return
+
+  const appUrl = process.env.NEXT_PUBLIC_APP_URL || "https://status.rootsofprogress.org"
+  const incidentLink = `${appUrl}/incidents/${incidentId}`
+
+  const text = [
+    `Site status alert: new incident — *${siteName}* is down`,
+    `URL: ${siteUrl}`,
+    error ? `Error: ${error}` : null,
+    `<${incidentLink}|View incident>`,
+  ]
+    .filter(Boolean)
+    .join("\n")
+
+  const body = JSON.stringify({ text })
+
+  for (const webhookUrl of webhookUrls) {
+    try {
+      const response = await fetch(webhookUrl, {
+        method: "POST",
+        headers: { "Content-Type": "application/json" },
+        body,
+      })
+      if (!response.ok) {
+        console.error("Slack webhook returned", response.status)
+      }
+    } catch (err) {
+      console.error("Failed to send Slack alert:", err)
+    }
+  }
+}
diff --git a/src/lib/supabase/types.ts b/src/lib/supabase/types.ts
index 8241eb0..b0490a6 100644
--- a/src/lib/supabase/types.ts
+++ b/src/lib/supabase/types.ts
@@ -26,7 +26,10 @@ export type Incident = {
 
 export type Contact = {
   id: string
-  email: string
+  type: 'email' | 'slack'
+  email: string | null
+  webhook_url: string | null
+  label: string | null
   created_at: string
 }
 
diff --git a/supabase/migrations/20250223000001_add_slack_contacts.sql b/supabase/migrations/20250223000001_add_slack_contacts.sql
new file mode 100644
index 0000000..e6edfe9
--- /dev/null
+++ b/supabase/migrations/20250223000001_add_slack_contacts.sql
@@ -0,0 +1,22 @@
+-- Add type and webhook_url columns to contacts for Slack alerting
+ALTER TABLE contacts
+  ADD COLUMN type text NOT NULL DEFAULT 'email' CHECK (type IN ('email', 'slack')),
+  ADD COLUMN webhook_url text,
+  ADD COLUMN label text;
+
+-- Make email nullable (Slack contacts won't have one)
+ALTER TABLE contacts ALTER COLUMN email DROP NOT NULL;
+
+-- Drop existing unique constraint on email
+ALTER TABLE contacts DROP CONSTRAINT contacts_email_key;
+
+-- Ensure email contacts have email, Slack contacts have webhook_url
+ALTER TABLE contacts ADD CONSTRAINT contacts_value_required
+  CHECK (
+    (type = 'email' AND email IS NOT NULL) OR
+    (type = 'slack' AND webhook_url IS NOT NULL)
+  );
+
+-- Unique constraints to prevent duplicate contacts
+CREATE UNIQUE INDEX contacts_email_unique ON contacts (email) WHERE email IS NOT NULL;
+CREATE UNIQUE INDEX contacts_webhook_url_unique ON contacts (webhook_url) WHERE webhook_url IS NOT NULL;