diff --git a/e2e/USER_STORIES.md b/e2e/USER_STORIES.md
index 4b1a56e8..b5260fed 100644
--- a/e2e/USER_STORIES.md
+++ b/e2e/USER_STORIES.md
@@ -1508,6 +1508,18 @@ Acceptance:
 - Payment history lists past invoices with amount and billing period, most
   recent first.
 
+### US-122 — Export and import a hosted relay's data
+
+As a space owner, I want to take a copy of everything my relay holds and put
+events back, so that I can keep a backup and move between hosts.
+
+Acceptance:
+
+- "Import / export data" in the relay actions menu opens a Relay data dialog,
+  whose "Download events" downloads the relay's events as `<subdomain>.jsonl`.
+- Importing a file reports how many events were stored and names the lines the
+  relay refused.
+
 ## Notifications & navigation
 
 ### US-103 — See and clear unread indicators
diff --git a/e2e/harness/net/http.ts b/e2e/harness/net/http.ts
index 4ad6ff40..6e7be392 100644
--- a/e2e/harness/net/http.ts
+++ b/e2e/harness/net/http.ts
@@ -452,7 +452,9 @@ export const mockHosting = async (context: BrowserContext, fixtures: HostingFixt
   await context.route(`${HOSTING_ORIGIN}/**`, route => {
     const request = route.request()
     const method = request.method()
-    const body: HostingRecord = request.postDataJSON() ?? {}
+    // An import posts JSONL, which postDataJSON() throws on. Every other write posts json.
+    const isJson = request.headers()["content-type"] === "application/json"
+    const body: HostingRecord = (isJson && request.postDataJSON()) || {}
     const [resource, id, sub, detail] = new URL(request.url()).pathname.split("/").filter(Boolean)
 
     const missing = (what: string) => route.fulfill({status: 404, json: {error: `No such ${what}`}})
@@ -528,6 +530,30 @@ export const mockHosting = async (context: BrowserContext, fixtures: HostingFixt
         return route.fulfill({json: {data: {activity: relay.activity ?? []}}})
       }
 
+      // The dump is whatever the fixture left on the record, served as the download itself rather
+      // than in a json envelope.
+      if (sub === "export") {
+        return route.fulfill({
+          contentType: "application/x-ndjson",
+          body: String(relay.events ?? ""),
+        })
+      }
+
+      // Storing events is the relay's own business, so the fake counts the lines and refuses the
+      // ones that don't look signed, which is the shape zooid reports problems in.
+      if (sub === "import") {
+        const lines = (request.postData() ?? "").split("\n").filter(line => line.trim())
+        const problems = lines.flatMap((line, index) =>
+          line.includes(`"sig"`) ? [] : [{line: index + 1, event_id: "", message: "invalid event"}],
+        )
+
+        return route.fulfill({
+          json: {
+            data: {imported: lines.length - problems.length, invalid: problems.length, problems},
+          },
+        })
+      }
+
       const updated = {...relay, ...(method === "PUT" ? body : {})}
 
       if (sub === "deactivate") {
diff --git a/e2e/specs/admin.spec.ts b/e2e/specs/admin.spec.ts
index 1a153eac..0cf90116 100644
--- a/e2e/specs/admin.spec.ts
+++ b/e2e/specs/admin.spec.ts
@@ -1101,3 +1101,40 @@ test("US-102 pause a relay and settle the bill", async ({seed, as}) => {
   await expect(invoices.nth(1)).toContainText("$5.00")
   await expect(invoices.nth(1)).toContainText(await period(paidPeriod))
 })
+
+test("US-122 export and import a hosted relay's data", async ({seed, as}) => {
+  const scenario = await seed(({relay, user}) => {
+    const space = relay("space")
+
+    space.room("general", {name: "General"})
+    space.join(user.alice, "general")
+  })
+
+  const {url} = scenario.space("space")
+  const dump = '{"id":"a","sig":"a"}\n{"id":"b","sig":"b"}\n'
+  const page = await as(users.alice, spacePath(url) + "/admin", {
+    hosting: {plans: PLANS, relays: [hostedRelay({events: dump})]},
+  })
+
+  await page.getByRole("button", {name: "Relay actions"}).click()
+  await menuItem(page, "Import / export data").click()
+
+  const modal = dialog(page, "Relay data")
+  const download = page.waitForEvent("download")
+
+  await modal.getByRole("button", {name: "Download events"}).click()
+
+  expect((await download).suggestedFilename()).toBe("space.jsonl")
+
+  await modal.locator("input[type=file]").setInputFiles({
+    name: "events.jsonl",
+    mimeType: "application/x-ndjson",
+    buffer: Buffer.from('{"id":"c","sig":"c"}\nnot an event\n'),
+  })
+
+  await modal.getByRole("button", {name: "Import events"}).click()
+
+  // The relay keeps what it could verify and says which line it refused
+  await expect(modal.getByText("Imported 1 event, skipped 1.")).toBeVisible()
+  await expect(modal.getByText("line 2: invalid event")).toBeVisible()
+})
diff --git a/src/app/components/hosting/DataTransferModal.svelte b/src/app/components/hosting/DataTransferModal.svelte
new file mode 100644
index 00000000..fd59f7cc
--- /dev/null
+++ b/src/app/components/hosting/DataTransferModal.svelte
@@ -0,0 +1,154 @@
+<script lang="ts">
+  import type {Maybe} from "@welshman/lib"
+  import {randomId} from "@welshman/lib"
+  import AltArrowLeft from "@assets/icons/alt-arrow-left.svg?dataurl"
+  import Download from "@assets/icons/download.svg?dataurl"
+  import Upload from "@assets/icons/upload.svg?dataurl"
+  import {downloadText} from "@lib/html"
+  import Icon from "@lib/components/Icon.svelte"
+  import Button from "@lib/components/Button.svelte"
+  import Divider from "@lib/components/Divider.svelte"
+  import Spinner from "@lib/components/Spinner.svelte"
+  import Modal from "@lib/components/Modal.svelte"
+  import ModalBody from "@lib/components/ModalBody.svelte"
+  import ModalHeader from "@lib/components/ModalHeader.svelte"
+  import ModalTitle from "@lib/components/ModalTitle.svelte"
+  import ModalSubtitle from "@lib/components/ModalSubtitle.svelte"
+  import ModalFooter from "@lib/components/ModalFooter.svelte"
+  import {pushToast} from "@app/toast"
+  import {
+    exportRelayData,
+    importRelayData,
+    HostingError,
+    type HostedRelay,
+    type ImportResult,
+  } from "@app/hosting"
+
+  type Props = {
+    relay: HostedRelay
+  }
+
+  const {relay}: Props = $props()
+
+  const inputId = randomId()
+
+  const relayLabel = relay.info_name || relay.subdomain
+
+  const back = () => history.back()
+
+  const onFileChange = (event: Event) => {
+    file = (event.target as HTMLInputElement).files?.[0]
+    result = undefined
+  }
+
+  const download = async () => {
+    exporting = true
+
+    try {
+      await downloadText(`${relay.subdomain}.jsonl`, await exportRelayData(relay.id))
+    } catch (e) {
+      pushToast({
+        theme: "error",
+        message: e instanceof HostingError ? e.message : "Failed to export relay data.",
+      })
+    } finally {
+      exporting = false
+    }
+  }
+
+  const upload = async () => {
+    if (file) {
+      importing = true
+
+      try {
+        result = await importRelayData(relay.id, file)
+      } catch (e) {
+        pushToast({
+          theme: "error",
+          message: e instanceof HostingError ? e.message : "Failed to import relay data.",
+        })
+      } finally {
+        importing = false
+      }
+    }
+  }
+
+  let exporting = $state(false)
+  let importing = $state(false)
+  let file: Maybe<File> = $state()
+  let result: Maybe<ImportResult> = $state()
+</script>
+
+<Modal>
+  <ModalBody>
+    <ModalHeader>
+      <ModalTitle>Relay data</ModalTitle>
+      <ModalSubtitle>
+        Everything {relayLabel} holds, as one event per line. Uploaded media is not included.
+      </ModalSubtitle>
+    </ModalHeader>
+
+    <div class="flex flex-col items-start gap-2">
+      <h3 class="text-sm font-semibold uppercase tracking-wider text-content-muted">Export</h3>
+      <p class="text-sm text-content-muted">
+        Download a copy of every event on the relay, for a backup or a move to another host.
+      </p>
+      <Button class="button button-primary" onclick={download} disabled={exporting}>
+        {#if !exporting}
+          <Icon icon={Download} size={4} />
+        {/if}
+        <Spinner loading={exporting}>Download events</Spinner>
+      </Button>
+    </div>
+
+    <Divider />
+
+    <div class="flex flex-col items-start gap-2">
+      <h3 class="text-sm font-semibold uppercase tracking-wider text-content-muted">Import</h3>
+      <p class="text-sm text-content-muted">
+        Add the events in a file to the relay. Each one carries its own signature, so a tampered or
+        unsigned line is skipped and reported, and importing the same file twice changes nothing.
+      </p>
+      <input
+        id={inputId}
+        type="file"
+        accept=".jsonl,.ndjson,.json,application/x-ndjson,application/json"
+        onchange={onFileChange}
+        class="hidden" />
+      <div class="flex flex-wrap items-center gap-2">
+        <label for={inputId} class="button button-neutral cursor-pointer">
+          <Icon icon={Upload} size={4} />
+          {file ? "Choose another file" : "Choose a file"}
+        </label>
+        {#if file}
+          <span class="min-w-0 break-all text-sm text-content-muted">{file.name}</span>
+        {/if}
+      </div>
+      <Button class="button button-primary" onclick={upload} disabled={importing || !file}>
+        <Spinner loading={importing}>Import events</Spinner>
+      </Button>
+    </div>
+
+    {#if result}
+      <div class="flex flex-col gap-2 rounded-2xl border border-line bg-surface-less p-4">
+        <p class="text-sm">
+          Imported {result.imported}
+          {result.imported === 1 ? "event" : "events"}{result.invalid > 0
+            ? `, skipped ${result.invalid}`
+            : ""}.
+        </p>
+        {#each result.problems?.slice(0, 5) || [] as problem (problem.line)}
+          <p class="break-all font-mono text-xs text-content-muted">
+            {problem.line ? `line ${problem.line}: ` : ""}{problem.message}
+          </p>
+        {/each}
+      </div>
+    {/if}
+  </ModalBody>
+  <ModalFooter>
+    <Button class="button button-link" onclick={back}>
+      <Icon icon={AltArrowLeft} />
+      Go back
+    </Button>
+  </ModalFooter>
+</Modal>
diff --git a/src/app/components/hosting/RelayDetailCard.svelte b/src/app/components/hosting/RelayDetailCard.svelte
index 6e6293e7..eb371b38 100644
--- a/src/app/components/hosting/RelayDetailCard.svelte
+++ b/src/app/components/hosting/RelayDetailCard.svelte
@@ -12,6 +12,7 @@
   import Copy from "@assets/icons/copy.svg?dataurl"
   import Refresh from "@assets/icons/refresh.svg?dataurl"
   import BillList from "@assets/icons/bill-list.svg?dataurl"
+  import Database from "@assets/icons/database.svg?dataurl"
   import {fly} from "@lib/transition"
   import {ucFirst} from "@lib/util"
   import Icon from "@lib/components/Icon.svelte"
@@ -26,6 +27,7 @@
   import ToggleInput from "@lib/components/ToggleInput.svelte"
   import Confirm from "@lib/components/Confirm.svelte"
   import CustomDomainModal from "@app/components/hosting/CustomDomainModal.svelte"
+  import DataTransferModal from "@app/components/hosting/DataTransferModal.svelte"
   import PlanModal from "@app/components/hosting/PlanModal.svelte"
   import {roomLists} from "@app/core"
   import RelayForm from "@app/components/hosting/RelayForm.svelte"
@@ -139,6 +141,10 @@
     })
   }
 
+  const openDataTransfer = () => {
+    pushModal(DataTransferModal, {relay: current})
+  }
+
   const openCustomDomain = () => {
     pushModal(CustomDomainModal, {relay: current, onUpdate: setCurrentAndFollowHost})
   }
@@ -268,6 +274,12 @@
                 Change plan
               </Button>
             </li>
+            <li>
+              <Button onclick={openDataTransfer}>
+                <Icon icon={Database} />
+                Import / export data
+              </Button>
+            </li>
             <li>
               {#if current.status === "active"}
                 <Button class="text-error" onclick={requestDeactivate}>
diff --git a/src/app/hosting.ts b/src/app/hosting.ts
index 5266a14d..a59d62ae 100644
--- a/src/app/hosting.ts
+++ b/src/app/hosting.ts
@@ -160,6 +160,19 @@ export type Activity = {
   resource_id: string
 }
 
+// One line of an imported JSONL file the relay could not store.
+export type ImportProblem = {
+  line: number
+  event_id: string
+  message: string
+}
+
+export type ImportResult = {
+  imported: number
+  invalid: number
+  problems?: ImportProblem[]
+}
+
 export class HostingError extends Error {
   status: number
 
@@ -201,29 +214,33 @@ const getAuthHeader = (): Promise<string> => {
 
 type HostingResponse<T> = {data: T; error?: string}
 
-export const hostingFetch = async <T>(method: string, path: string, body?: unknown): Promise<T> => {
-  const headers: Record<string, string> = {
-    Accept: "application/json",
-    Authorization: await getAuthHeader(),
-  }
-
-  if (body !== undefined) headers["Content-Type"] = "application/json"
-
-  const response = await fetch(new URL(path, HOSTING_BACKEND_URL).toString(), {
+const hostingRequest = async (method: string, path: string, init: RequestInit = {}) =>
+  fetch(new URL(path, HOSTING_BACKEND_URL).toString(), {
+    ...init,
     method,
-    headers,
-    body: body === undefined ? undefined : JSON.stringify(body),
+    headers: {
+      Accept: "application/json",
+      Authorization: await getAuthHeader(),
+      ...init.headers,
+    },
   })
 
+const hostingJson = async <T>(response: Response): Promise<T> => {
   const payload: Maybe<HostingResponse<T>> = await response.json().catch(() => undefined)
 
-  if (!response.ok || !payload) {
-    throw new HostingError(payload?.error || `Request failed (${response.status})`, response.status)
-  }
+  if (response.ok && payload) return payload.data
 
-  return payload.data
+  throw new HostingError(payload?.error || `Request failed (${response.status})`, response.status)
 }
 
+export const hostingFetch = async <T>(method: string, path: string, body?: unknown): Promise<T> =>
+  hostingJson<T>(
+    await hostingRequest(method, path, {
+      headers: body === undefined ? undefined : {"Content-Type": "application/json"},
+      body: body === undefined ? undefined : JSON.stringify(body),
+    }),
+  )
+
 export const listPlans = () => hostingFetch<Plan[]>("GET", "/plans")
 
 export const createTenant = (returnUrl: string) =>
@@ -273,6 +290,27 @@ export const listRelayMembers = (id: string) =>
 export const listRelayActivity = (id: string) =>
   hostingFetch<{activity: Activity[]}>("GET", `/relays/${id}/activity`)
 
+// Every event the relay holds, as JSONL. Fetched rather than linked, since the
+// nip 98 auth header can't ride on an <a href>.
+export const exportRelayData = async (id: string) => {
+  const response = await hostingRequest("GET", `/relays/${id}/export`)
+
+  if (response.ok) return response.text()
+
+  // Only the failure path is a json envelope; success is the dump itself.
+  return hostingJson<string>(response)
+}
+
+// Events keep their own signatures, so the relay validates them itself and
+// reports the lines it refused.
+export const importRelayData = async (id: string, file: Blob) =>
+  hostingJson<ImportResult>(
+    await hostingRequest("POST", `/relays/${id}/import`, {
+      headers: {"Content-Type": "application/x-ndjson"},
+      body: file,
+    }),
+  )
+
 export const getInvoice = (id: string) => hostingFetch<Invoice>("GET", `/invoices/${id}`)
 
 export const listInvoiceItems = (invoiceId: string) =>