diff --git a/.airtap.yml b/.airtap.yml
new file mode 100644
index 0000000..225fb41
--- /dev/null
+++ b/.airtap.yml
@@ -0,0 +1,7 @@
+providers:
+  - airtap-playwright
+
+browsers:
+  - name: chromium
+  - name: firefox
+  - name: webkit
diff --git a/.travis.yml b/.travis.yml
index acaad06..71bbf0c 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,9 +1,8 @@
 language: node_js
 
 node_js:
-  - 6
-  - 8
   - 10
   - 12
+  - 14
 
 after_success: npm run coverage
diff --git a/index.js b/index.js
index 1f7dd9d..6915d7c 100644
--- a/index.js
+++ b/index.js
@@ -1,13 +1,9 @@
 'use strict'
 
-// For (old) browser support
-var xtend = require('xtend')
-var assign = require('xtend/mutable')
+module.exports = function supports (...manifests) {
+  const manifest = manifests.reduce((acc, m) => Object.assign(acc, m), {})
 
-module.exports = function supports () {
-  var manifest = xtend.apply(null, arguments)
-
-  return assign(manifest, {
+  return Object.assign(manifest, {
     // Features of abstract-leveldown
     bufferKeys: manifest.bufferKeys || false,
     snapshots: manifest.snapshots || false,
@@ -30,6 +26,6 @@ module.exports = function supports () {
     encodings: manifest.encodings || false,
 
     // Methods that are not part of abstract-leveldown or levelup
-    additionalMethods: xtend(manifest.additionalMethods)
+    additionalMethods: Object.assign({}, manifest.additionalMethods)
   })
 }
diff --git a/package.json b/package.json
index fecb126..db9c2e9 100644
--- a/package.json
+++ b/package.json
@@ -5,11 +5,9 @@
   "license": "MIT",
   "scripts": {
     "test": "standard && hallmark && (nyc -s node test/self.js | faucet) && nyc report",
-    "test-browser-local": "airtap --coverage --local test/self.js",
+    "test-browsers-local": "airtap --coverage test/self.js",
     "coverage": "nyc report --reporter=text-lcov | coveralls",
-    "hallmark": "hallmark --fix",
-    "dependency-check": "dependency-check --no-dev . test/*.js",
-    "prepublishOnly": "npm run dependency-check"
+    "hallmark": "hallmark --fix"
   },
   "files": [
     "test",
@@ -17,18 +15,16 @@
     "CONTRIBUTORS.md",
     "index.js"
   ],
-  "dependencies": {
-    "xtend": "^4.0.2"
-  },
+  "dependencies": {},
   "devDependencies": {
-    "airtap": "^3.0.0",
+    "airtap": "^4.0.3",
+    "airtap-playwright": "^1.0.1",
     "coveralls": "^3.0.6",
-    "dependency-check": "^4.1.0",
     "faucet": "^0.0.1",
     "hallmark": "^3.1.0",
     "level-community": "^3.0.0",
     "nyc": "^14.1.1",
-    "standard": "^14.3.1",
+    "standard": "^16.0.3",
     "tape": "^5.0.1"
   },
   "hallmark": {
@@ -48,6 +44,6 @@
     "manifest"
   ],
   "engines": {
-    "node": ">=6"
+    "node": ">=10"
   }
 }
diff --git a/test/cloneable.js b/test/cloneable.js
index 2712416..2a64b18 100644
--- a/test/cloneable.js
+++ b/test/cloneable.js
@@ -1,13 +1,13 @@
 'use strict'
 
-var supports = require('..')
+const supports = require('..')
 
 // Every object in a manifest must have a unique identity, to avoid accidental
 // mutation. In supports() we only shallowly clone the manifest object itself
 // and additionalMethods. If in the future we add more objects to manifests,
 // this test will break and we'll know to start performing a deep clone.
 module.exports = function cloneable (t, manifest) {
-  var copy = supports(manifest)
+  const copy = supports(manifest)
   verifyUnique(t, 'manifest', manifest, copy)
 }
 
diff --git a/test/index.js b/test/index.js
index aba38bd..0208416 100644
--- a/test/index.js
+++ b/test/index.js
@@ -1,19 +1,18 @@
 'use strict'
 
-var xtend = require('xtend')
-var shape = require('./shape')
-var cloneable = require('./cloneable')
+const shape = require('./shape')
+const cloneable = require('./cloneable')
 
 module.exports = function suite (test, testCommon) {
   test('db has manifest', function (t) {
-    var db = testCommon.factory()
-    var manifest = db.supports
+    const db = testCommon.factory()
+    const manifest = db.supports
 
     shape(t, manifest)
     cloneable(t, manifest)
 
-    var before = xtend(manifest, {
-      additionalMethods: xtend(manifest.additionalMethods)
+    const before = Object.assign({}, manifest, {
+      additionalMethods: Object.assign({}, manifest.additionalMethods)
     })
 
     db.open(function (err) {
diff --git a/test/self.js b/test/self.js
index 3c7d75b..5b3678b 100644
--- a/test/self.js
+++ b/test/self.js
@@ -1,9 +1,9 @@
 'use strict'
 
-var test = require('tape')
-var supports = require('..')
-var shape = require('./shape')
-var cloneable = require('./cloneable')
+const test = require('tape')
+const supports = require('..')
+const shape = require('./shape')
+const cloneable = require('./cloneable')
 
 test('no options', function (t) {
   shape(t, supports())
@@ -13,7 +13,7 @@ test('no options', function (t) {
 
 test('falsy options', function (t) {
   ;[null, false, undefined, 0, ''].forEach(function (value) {
-    var manifest = supports({
+    const manifest = supports({
       bufferKeys: value,
       additionalMethods: {
         foo: value
@@ -29,7 +29,7 @@ test('falsy options', function (t) {
 
 test('truthy options', function (t) {
   ;[true, {}, 'yes', 1, []].forEach(function (value) {
-    var manifest = supports({
+    const manifest = supports({
       streams: value,
       additionalMethods: {
         foo: value
@@ -45,9 +45,9 @@ test('truthy options', function (t) {
 })
 
 test('merges input objects without mutating them', function (t) {
-  var input1 = { bufferKeys: null, streams: false }
-  var input2 = { streams: true, additionalMethods: {} }
-  var manifest = supports(input1, input2)
+  const input1 = { bufferKeys: null, streams: false }
+  const input2 = { streams: true, additionalMethods: {} }
+  const manifest = supports(input1, input2)
 
   manifest.foobar = true
   manifest.additionalMethods.baz = true
@@ -61,15 +61,15 @@ test('merges input objects without mutating them', function (t) {
 })
 
 test('inherits additionalMethods', function (t) {
-  var manifest = supports({ additionalMethods: { foo: true } }, {})
+  const manifest = supports({ additionalMethods: { foo: true } }, {})
   t.same(manifest.additionalMethods, { foo: true })
   t.end()
 })
 
 test('does not merge additionalMethods', function (t) {
-  var input1 = { additionalMethods: { foo: true } }
-  var input2 = { additionalMethods: { bar: true } }
-  var manifest = supports(input1, input2)
+  const input1 = { additionalMethods: { foo: true } }
+  const input2 = { additionalMethods: { bar: true } }
+  const manifest = supports(input1, input2)
   t.same(manifest.additionalMethods, { bar: true })
   t.end()
 })
diff --git a/test/shape.js b/test/shape.js
index dc96b54..82198ec 100644
--- a/test/shape.js
+++ b/test/shape.js
@@ -1,12 +1,12 @@
 'use strict'
 
-var hasOwnProperty = Object.prototype.hasOwnProperty
+const hasOwnProperty = Object.prototype.hasOwnProperty
 
 module.exports = function shape (t, manifest) {
   t.ok(isObject(manifest), 'manifest is object')
   t.ok(isObject(manifest.additionalMethods), 'additionalMethods is object')
 
-  for (var k in manifest) {
+  for (const k in manifest) {
     if (!hasOwnProperty.call(manifest, k)) continue
 
     if (manifest[k]) {