diff --git a/.github/workflows/installer-test.yml b/.github/workflows/installer-test.yml
new file mode 100644
index 00000000000..d77c277a18e
--- /dev/null
+++ b/.github/workflows/installer-test.yml
@@ -0,0 +1,165 @@
+name: "Installer test"
+
+# Exercises bin/installer.sh and bin/installer.ps1 end-to-end so the
+# one-line install paths in the README stay working.
+
+on:
+  push:
+    paths:
+      - "bin/installer.sh"
+      - "bin/installer.ps1"
+      - ".github/workflows/installer-test.yml"
+  pull_request:
+    paths:
+      - "bin/installer.sh"
+      - "bin/installer.ps1"
+      - ".github/workflows/installer-test.yml"
+
+permissions:
+  contents: read
+
+jobs:
+  shellcheck:
+    name: shellcheck
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+      - name: Run shellcheck on installer.sh
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y shellcheck
+          shellcheck bin/installer.sh
+
+  installer-posix:
+    name: end-to-end install (${{ matrix.os }})
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, macos-latest]
+    steps:
+      - uses: actions/checkout@v6
+
+      - uses: actions/setup-node@v6
+        with:
+          node-version: 22
+
+      - name: Pre-install pnpm (avoid sudo prompt in the installer)
+        run: npm install -g pnpm
+
+      - name: Run bin/installer.sh against this commit
+        env:
+          ETHERPAD_DIR: ${{ runner.temp }}/etherpad-installer-test
+          ETHERPAD_REPO: ${{ github.server_url }}/${{ github.repository }}.git
+          ETHERPAD_BRANCH: ${{ github.head_ref || github.ref_name }}
+          NO_COLOR: "1"
+        run: sh ./bin/installer.sh
+
+      - name: Verify clone + dependencies + build artifacts
+        shell: bash
+        env:
+          ETHERPAD_DIR: ${{ runner.temp }}/etherpad-installer-test
+        run: |
+          set -eux
+          test -d "$ETHERPAD_DIR/.git"
+          test -f "$ETHERPAD_DIR/package.json"
+          test -d "$ETHERPAD_DIR/node_modules"
+          test -d "$ETHERPAD_DIR/src/node_modules"
+          # build:etherpad copies the admin SPA into src/templates/admin
+          test -f "$ETHERPAD_DIR/src/templates/admin/index.html"
+
+      - name: Smoke test - start Etherpad and curl /api
+        shell: bash
+        env:
+          ETHERPAD_DIR: ${{ runner.temp }}/etherpad-installer-test
+        run: |
+          set -eu
+          cd "$ETHERPAD_DIR"
+          pnpm run prod >/tmp/etherpad.log 2>&1 &
+          PID=$!
+          # Wait up to 60s for the API to come up.
+          ok=0
+          for i in $(seq 1 60); do
+            if curl -fsS http://localhost:9001/api >/dev/null 2>&1; then
+              echo "Etherpad answered on /api after ${i}s"
+              ok=1
+              break
+            fi
+            sleep 1
+          done
+          if [ "$ok" != "1" ]; then
+            echo "Etherpad did not start within 60s. Last 200 lines of log:" >&2
+            tail -200 /tmp/etherpad.log >&2 || true
+            kill "$PID" 2>/dev/null || true
+            exit 1
+          fi
+          kill "$PID" 2>/dev/null || true
+          wait "$PID" 2>/dev/null || true
+
+  installer-windows:
+    name: end-to-end install (windows-latest)
+    runs-on: windows-latest
+    steps:
+      - uses: actions/checkout@v6
+
+      - uses: actions/setup-node@v6
+        with:
+          node-version: 22
+
+      - name: Pre-install pnpm
+        run: npm install -g pnpm
+
+      - name: Run bin/installer.ps1 against this commit
+        shell: pwsh
+        env:
+          ETHERPAD_DIR: ${{ runner.temp }}\etherpad-installer-test
+          ETHERPAD_REPO: ${{ github.server_url }}/${{ github.repository }}.git
+          ETHERPAD_BRANCH: ${{ github.head_ref || github.ref_name }}
+          NO_COLOR: "1"
+        run: ./bin/installer.ps1
+
+      - name: Verify clone + dependencies + build artifacts
+        shell: pwsh
+        env:
+          ETHERPAD_DIR: ${{ runner.temp }}\etherpad-installer-test
+        run: |
+          if (-not (Test-Path "$env:ETHERPAD_DIR\.git"))                      { throw '.git missing' }
+          if (-not (Test-Path "$env:ETHERPAD_DIR\package.json"))              { throw 'package.json missing' }
+          if (-not (Test-Path "$env:ETHERPAD_DIR\node_modules"))              { throw 'node_modules missing' }
+          if (-not (Test-Path "$env:ETHERPAD_DIR\src\node_modules"))          { throw 'src/node_modules missing' }
+          if (-not (Test-Path "$env:ETHERPAD_DIR\src\templates\admin\index.html")) { throw 'admin SPA missing' }
+
+      - name: Smoke test - start Etherpad and curl /api
+        shell: pwsh
+        env:
+          ETHERPAD_DIR: ${{ runner.temp }}\etherpad-installer-test
+        run: |
+          Push-Location $env:ETHERPAD_DIR
+          $logPath = Join-Path $env:RUNNER_TEMP 'etherpad.log'
+          # pnpm on Windows is a .cmd shim, which Start-Process can't run
+          # directly — wrap it in cmd.exe.
+          $proc = Start-Process -FilePath cmd.exe `
+                                -ArgumentList '/c','pnpm','run','prod' `
+                                -RedirectStandardOutput $logPath `
+                                -RedirectStandardError "$logPath.err" `
+                                -PassThru -NoNewWindow
+          $ok = $false
+          for ($i = 1; $i -le 90; $i++) {
+            try {
+              Invoke-WebRequest -UseBasicParsing -Uri http://localhost:9001/api -TimeoutSec 2 | Out-Null
+              Write-Host "Etherpad answered on /api after ${i}s"
+              $ok = $true
+              break
+            } catch { Start-Sleep -Seconds 1 }
+          }
+          if (-not $ok) {
+            Write-Host 'Etherpad did not start within 90s. Last 200 lines of log (stdout):'
+            if (Test-Path $logPath) { Get-Content $logPath -Tail 200 }
+            Write-Host 'Last 200 lines of stderr:'
+            if (Test-Path "$logPath.err") { Get-Content "$logPath.err" -Tail 200 }
+            Stop-Process -Id $proc.Id -Force -ErrorAction SilentlyContinue
+            Pop-Location
+            exit 1
+          }
+          Stop-Process -Id $proc.Id -Force -ErrorAction SilentlyContinue
+          Pop-Location
diff --git a/README.md b/README.md
index 492ad015d3c..5c0c8c48b1a 100644
--- a/README.md
+++ b/README.md
@@ -43,6 +43,43 @@ We're looking for maintainers and have some funding available.  Please contact J
 
 ## Installation
 
+### Quick install (one-liner)
+
+The fastest way to get Etherpad running. Requires `git` and Node.js >= 20.
+
+**macOS / Linux / WSL:**
+
+```sh
+curl -fsSL https://raw.githubusercontent.com/ether/etherpad-lite/master/bin/installer.sh | sh
+```
+
+**Windows (PowerShell):**
+
+```powershell
+irm https://raw.githubusercontent.com/ether/etherpad-lite/master/bin/installer.ps1 | iex
+```
+
+Both installers clone Etherpad into `./etherpad-lite`, install dependencies, and
+build the frontend. When the installer finishes, run:
+
+```sh
+cd etherpad-lite && pnpm run prod
+```
+
+Then open <http://localhost:9001>.
+
+To install and start in one go:
+
+```sh
+# macOS / Linux / WSL
+ETHERPAD_RUN=1 sh -c "$(curl -fsSL https://raw.githubusercontent.com/ether/etherpad-lite/master/bin/installer.sh)"
+```
+
+```powershell
+# Windows
+$env:ETHERPAD_RUN=1; irm https://raw.githubusercontent.com/ether/etherpad-lite/master/bin/installer.ps1 | iex
+```
+
 ### Docker-Compose
 
 ```yaml
@@ -100,7 +137,7 @@ volumes:
 
 ### Requirements
 
-[Node.js](https://nodejs.org/).
+[Node.js](https://nodejs.org/) >= 20.
 
 ### Windows, macOS, Linux
 
diff --git a/bin/installer.ps1 b/bin/installer.ps1
new file mode 100644
index 00000000000..f1295b72fd2
--- /dev/null
+++ b/bin/installer.ps1
@@ -0,0 +1,155 @@
+# Etherpad one-line installer for Windows (PowerShell).
+#
+# Usage:
+#   irm https://raw.githubusercontent.com/ether/etherpad-lite/master/bin/installer.ps1 | iex
+#
+# Optional environment variables:
+#   $env:ETHERPAD_DIR     Directory to install into (default: .\etherpad-lite)
+#   $env:ETHERPAD_BRANCH  Branch / tag to clone (default: master)
+#   $env:ETHERPAD_REPO    Repo URL (default: https://github.com/ether/etherpad-lite.git)
+#   $env:ETHERPAD_RUN     If "1", start Etherpad after install
+#   $env:NO_COLOR         If set, disables coloured output
+
+#Requires -Version 5.1
+
+$ErrorActionPreference = 'Stop'
+
+# ---------- pretty output ----------
+$useColor = -not $env:NO_COLOR
+function Write-Step([string]$msg) {
+    if ($useColor) { Write-Host "==> $msg" -ForegroundColor Green }
+    else           { Write-Host "==> $msg" }
+}
+function Write-Warn([string]$msg) {
+    if ($useColor) { Write-Host "==> $msg" -ForegroundColor Yellow }
+    else           { Write-Host "==> $msg" }
+}
+function Write-Fatal([string]$msg) {
+    if ($useColor) { Write-Host "==> $msg" -ForegroundColor Red }
+    else           { Write-Host "==> $msg" }
+    exit 1
+}
+
+function Test-Cmd([string]$name) {
+    return [bool](Get-Command $name -ErrorAction SilentlyContinue)
+}
+
+# ---------- defaults ----------
+$EtherpadDir    = if ($env:ETHERPAD_DIR)    { $env:ETHERPAD_DIR }    else { 'etherpad-lite' }
+$EtherpadBranch = if ($env:ETHERPAD_BRANCH) { $env:ETHERPAD_BRANCH } else { 'master' }
+$EtherpadRepo   = if ($env:ETHERPAD_REPO)   { $env:ETHERPAD_REPO }   else { 'https://github.com/ether/etherpad-lite.git' }
+$RequiredNodeMajor = 20
+
+Write-Step 'Etherpad installer'
+
+# ---------- prerequisite checks ----------
+if (-not (Test-Cmd git)) {
+    Write-Fatal 'git is required but not installed. See https://git-scm.com/download/win'
+}
+if (-not (Test-Cmd node)) {
+    Write-Fatal "Node.js is required (>= $RequiredNodeMajor). Install it from https://nodejs.org"
+}
+
+$nodeMajor = [int](node -p 'process.versions.node.split(".")[0]')
+if ($nodeMajor -lt $RequiredNodeMajor) {
+    $nodeVer = (node --version)
+    Write-Fatal "Node.js >= $RequiredNodeMajor required. You have $nodeVer."
+}
+
+if (-not (Test-Cmd pnpm)) {
+    Write-Step 'Installing pnpm globally'
+    if (-not (Test-Cmd npm)) {
+        Write-Fatal "npm not found. Install Node.js >= $RequiredNodeMajor."
+    }
+    npm install -g pnpm
+    if ($LASTEXITCODE -ne 0) {
+        Write-Fatal 'Failed to install pnpm. Install it manually: https://pnpm.io/installation'
+    }
+    if (-not (Test-Cmd pnpm)) {
+        Write-Fatal 'pnpm install reported success but pnpm is still not on PATH. Open a new shell and re-run.'
+    }
+}
+
+# ---------- clone ----------
+if (Test-Path $EtherpadDir) {
+    if (Test-Path (Join-Path $EtherpadDir '.git')) {
+        Write-Warn "$EtherpadDir already exists; updating to $EtherpadBranch."
+        Push-Location $EtherpadDir
+        try {
+            # Verify the existing checkout points at the expected remote.
+            $existingRemote = (git remote get-url origin 2>$null)
+            if ($existingRemote -and $existingRemote -ne $EtherpadRepo) {
+                Write-Fatal "$EtherpadDir is checked out from '$existingRemote', expected '$EtherpadRepo'. Refusing to overwrite."
+            }
+
+            # Refuse to clobber meaningful local changes. pnpm-lock.yaml is
+            # excluded because `pnpm i` rewrites it during installation,
+            # which would otherwise make every re-run of the installer fail.
+            $statusLines = (git status --porcelain) -split "`n" |
+                Where-Object { $_ -and ($_ -notmatch '\bpnpm-lock\.yaml$') }
+            if ($statusLines) {
+                $statusLines | ForEach-Object { Write-Host $_ }
+                Write-Fatal "$EtherpadDir has uncommitted changes. Commit/stash them or remove the directory."
+            }
+
+            git fetch --tags --prune origin
+            if ($LASTEXITCODE -ne 0) { Write-Fatal "git fetch failed in $EtherpadDir" }
+
+            # Discard any pnpm-lock.yaml changes from a prior pnpm install
+            # so the subsequent checkout doesn't refuse to overwrite.
+            git checkout -- pnpm-lock.yaml 2>$null
+
+            # Switch to the requested branch / tag and fast-forward to it.
+            git show-ref --verify --quiet "refs/remotes/origin/$EtherpadBranch"
+            $isBranch = ($LASTEXITCODE -eq 0)
+            git show-ref --verify --quiet "refs/tags/$EtherpadBranch"
+            $isTag = ($LASTEXITCODE -eq 0)
+
+            if ($isBranch) {
+                git checkout -B $EtherpadBranch "origin/$EtherpadBranch"
+                if ($LASTEXITCODE -ne 0) { Write-Fatal "git checkout $EtherpadBranch failed" }
+            } elseif ($isTag) {
+                git checkout --detach "refs/tags/$EtherpadBranch"
+                if ($LASTEXITCODE -ne 0) { Write-Fatal "git checkout tag $EtherpadBranch failed" }
+            } else {
+                Write-Fatal "Branch or tag '$EtherpadBranch' not found on origin."
+            }
+
+            $installedRev = (git rev-parse --short HEAD)
+            Write-Step "Updated $EtherpadDir to $EtherpadBranch @ $installedRev"
+        } finally {
+            Pop-Location
+        }
+    } else {
+        Write-Fatal "$EtherpadDir exists and is not a git checkout. Aborting."
+    }
+} else {
+    Write-Step "Cloning Etherpad ($EtherpadBranch) into $EtherpadDir"
+    git clone --depth 1 --branch $EtherpadBranch $EtherpadRepo $EtherpadDir
+    if ($LASTEXITCODE -ne 0) { Write-Fatal 'git clone failed.' }
+}
+
+Push-Location $EtherpadDir
+
+# ---------- install + build ----------
+Write-Step 'Installing dependencies (pnpm i)'
+pnpm i
+if ($LASTEXITCODE -ne 0) { Pop-Location; Write-Fatal 'pnpm i failed.' }
+
+Write-Step 'Building Etherpad (pnpm run build:etherpad)'
+pnpm run build:etherpad
+if ($LASTEXITCODE -ne 0) { Pop-Location; Write-Fatal 'pnpm run build:etherpad failed.' }
+
+# ---------- done ----------
+Write-Host ''
+if ($useColor) { Write-Host "🎉 Etherpad is installed in $EtherpadDir" -ForegroundColor Green }
+else           { Write-Host "Etherpad is installed in $EtherpadDir" }
+Write-Host 'To start Etherpad:'
+Write-Host "  cd $EtherpadDir; pnpm run prod"
+Write-Host 'Then open http://localhost:9001 in your browser.'
+Write-Host ''
+
+if ($env:ETHERPAD_RUN -eq '1') {
+    Write-Step 'Starting Etherpad on http://localhost:9001'
+    pnpm run prod
+}
diff --git a/bin/installer.sh b/bin/installer.sh
new file mode 100755
index 00000000000..151aafd50cd
--- /dev/null
+++ b/bin/installer.sh
@@ -0,0 +1,133 @@
+#!/bin/sh
+#
+# Etherpad one-line installer.
+#
+# Usage:
+#   curl -fsSL https://raw.githubusercontent.com/ether/etherpad-lite/master/bin/installer.sh | sh
+#
+# Optional environment variables:
+#   ETHERPAD_DIR     Directory to install into (default: ./etherpad-lite)
+#   ETHERPAD_BRANCH  Branch / tag to clone (default: master)
+#   ETHERPAD_RUN     If set to 1, start Etherpad after install
+#   NO_COLOR         If set, disables coloured output
+
+set -eu
+
+# ---------- pretty output ----------
+if [ -z "${NO_COLOR:-}" ] && [ -t 1 ]; then
+  bold=$(printf '\033[1m')
+  green=$(printf '\033[32m')
+  red=$(printf '\033[31m')
+  yellow=$(printf '\033[33m')
+  reset=$(printf '\033[0m')
+else
+  bold=''; green=''; red=''; yellow=''; reset=''
+fi
+
+step()  { printf '%s==>%s %s%s%s\n' "$green" "$reset" "$bold" "$*" "$reset"; }
+warn()  { printf '%s==>%s %s\n' "$yellow" "$reset" "$*" >&2; }
+fatal() { printf '%s==>%s %s\n' "$red" "$reset" "$*" >&2; exit 1; }
+
+is_cmd() { command -v "$1" >/dev/null 2>&1; }
+
+# ---------- defaults ----------
+ETHERPAD_DIR="${ETHERPAD_DIR:-etherpad-lite}"
+ETHERPAD_BRANCH="${ETHERPAD_BRANCH:-master}"
+ETHERPAD_REPO="${ETHERPAD_REPO:-https://github.com/ether/etherpad-lite.git}"
+REQUIRED_NODE_MAJOR=20
+
+step "Etherpad installer"
+
+# ---------- prerequisite checks ----------
+is_cmd git || fatal "git is required but not installed. See https://git-scm.com/downloads"
+
+if ! is_cmd node; then
+  fatal "Node.js is required (>= ${REQUIRED_NODE_MAJOR}). Install it from https://nodejs.org"
+fi
+
+NODE_MAJOR=$(node -p "process.versions.node.split('.')[0]")
+if [ "$NODE_MAJOR" -lt "$REQUIRED_NODE_MAJOR" ]; then
+  fatal "Node.js >= ${REQUIRED_NODE_MAJOR} required. You have $(node --version)."
+fi
+
+if ! is_cmd pnpm; then
+  step "Installing pnpm globally"
+  is_cmd npm || fatal "npm not found. Install Node.js >= ${REQUIRED_NODE_MAJOR}."
+  if ! npm install -g pnpm 2>/dev/null; then
+    warn "Global npm install requires elevated permissions; retrying with sudo."
+    is_cmd sudo || fatal "sudo not available. Install pnpm manually: https://pnpm.io/installation"
+    sudo npm install -g pnpm || \
+      fatal "Failed to install pnpm. Install it manually: https://pnpm.io/installation"
+  fi
+  is_cmd pnpm || \
+    fatal "pnpm install reported success but pnpm is still not on PATH. Open a new shell and re-run."
+fi
+
+# ---------- clone ----------
+if [ -d "$ETHERPAD_DIR" ]; then
+  if [ -d "$ETHERPAD_DIR/.git" ]; then
+    warn "$ETHERPAD_DIR already exists; updating to $ETHERPAD_BRANCH."
+    cd "$ETHERPAD_DIR" || fatal "Cannot cd into $ETHERPAD_DIR"
+
+    # Verify the existing checkout points at the expected remote.
+    EXISTING_REMOTE=$(git remote get-url origin 2>/dev/null || echo "")
+    if [ -n "$EXISTING_REMOTE" ] && [ "$EXISTING_REMOTE" != "$ETHERPAD_REPO" ]; then
+      fatal "$ETHERPAD_DIR is checked out from '$EXISTING_REMOTE', expected '$ETHERPAD_REPO'. Refusing to overwrite."
+    fi
+
+    # Refuse to clobber meaningful local changes. pnpm-lock.yaml is excluded
+    # because `pnpm i` rewrites it during installation, which would otherwise
+    # make every re-run of the installer fail.
+    DIRTY=$(git status --porcelain 2>/dev/null | awk '$2 != "pnpm-lock.yaml" {print}')
+    if [ -n "$DIRTY" ]; then
+      printf '%s\n' "$DIRTY" >&2
+      fatal "$ETHERPAD_DIR has uncommitted changes. Commit/stash them or remove the directory."
+    fi
+
+    git fetch --tags --prune origin || fatal "git fetch failed in $ETHERPAD_DIR"
+
+    # Discard any pnpm-lock.yaml changes from a prior pnpm install so the
+    # subsequent checkout doesn't refuse to overwrite local changes.
+    git checkout -- pnpm-lock.yaml 2>/dev/null || true
+
+    # Switch to the requested branch / tag and fast-forward to it.
+    if git show-ref --verify --quiet "refs/remotes/origin/$ETHERPAD_BRANCH"; then
+      git checkout -B "$ETHERPAD_BRANCH" "origin/$ETHERPAD_BRANCH" || \
+        fatal "git checkout $ETHERPAD_BRANCH failed"
+    elif git show-ref --verify --quiet "refs/tags/$ETHERPAD_BRANCH"; then
+      git checkout --detach "refs/tags/$ETHERPAD_BRANCH" || \
+        fatal "git checkout tag $ETHERPAD_BRANCH failed"
+    else
+      fatal "Branch or tag '$ETHERPAD_BRANCH' not found on origin."
+    fi
+
+    INSTALLED_REV=$(git rev-parse --short HEAD)
+    step "Updated $ETHERPAD_DIR to $ETHERPAD_BRANCH @ $INSTALLED_REV"
+    cd - >/dev/null || exit 1
+  else
+    fatal "$ETHERPAD_DIR exists and is not a git checkout. Aborting."
+  fi
+else
+  step "Cloning Etherpad ($ETHERPAD_BRANCH) into $ETHERPAD_DIR"
+  git clone --depth 1 --branch "$ETHERPAD_BRANCH" "$ETHERPAD_REPO" "$ETHERPAD_DIR"
+fi
+
+cd "$ETHERPAD_DIR"
+
+# ---------- install + build ----------
+step "Installing dependencies (pnpm i)"
+pnpm i
+
+step "Building Etherpad (pnpm run build:etherpad)"
+pnpm run build:etherpad
+
+# ---------- done ----------
+printf '\n%s🎉 Etherpad is installed in %s%s\n' "$green" "$ETHERPAD_DIR" "$reset"
+printf 'To start Etherpad:\n'
+printf '  cd %s && pnpm run prod\n' "$ETHERPAD_DIR"
+printf 'Then open http://localhost:9001 in your browser.\n\n'
+
+if [ "${ETHERPAD_RUN:-0}" = "1" ]; then
+  step "Starting Etherpad on http://localhost:9001"
+  exec pnpm run prod
+fi