diff --git a/.circleci/config.yml b/.circleci/config.yml
index 7b2316bb..6bb370fe 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -6,7 +6,7 @@ defaults: &defaults
   working_directory: ~/axe-core-gems
 
 orbs:
-  browser-tools: circleci/browser-tools@1.4.3
+  browser-tools: circleci/browser-tools@1.4.8
   node: circleci/node@5.0.0
 
 commands:
@@ -14,9 +14,7 @@ commands:
     description: Install dependencies and bootstrap packages
     steps:
       - checkout
-      - browser-tools/install-browser-tools:
-          # TODO: remove when chromedriver downloads are fixed
-          chrome-version: 116.0.5845.96
+      - browser-tools/install-browser-tools
       - node/install:
           node-version: "16.13"
       - run: gem install bundler # setup bundler
diff --git a/.github/workflows/sync-master-develop.yml b/.github/workflows/sync-master-develop.yml
index e15ff080..3df440bf 100644
--- a/.github/workflows/sync-master-develop.yml
+++ b/.github/workflows/sync-master-develop.yml
@@ -1,19 +1,19 @@
 name: Sync master/develop branches
 
 on:
-  pull_request:
-    types: [closed]
-    branches: master
+  push:
+    branches:
+      - master
 
 jobs:
   create_sync_pull_request:
     runs-on: ubuntu-latest
     timeout-minutes: 2
     steps:
-      - uses: dequelabs/action-sync-branches@v1
+      - uses: dequelabs/action-sync-branches@v1.0.1
         with:
-          github-token: ${{ secrets.GITHUB_TOKEN }}
+          github-token: ${{ secrets.PAT }}
           pr-title: "chore: merge master into develop"
-          pr-reviewers: adnoc,michael-siek,stephenmathieson
+          pr-team-reviewers: axe-api-team
           pr-labels: chore
-          pr-template: .github/PULL_REQUEST_TEMPLATE.md
\ No newline at end of file
+          pr-template: .github/PULL_REQUEST_TEMPLATE.md
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2db13616..4d3ff5a8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,18 @@
 
 All notable changes to this project will be documented in this file. See [commit-and-tag-version](https://github.com/absolute-version/commit-and-tag-version) for commit guidelines.
 
+## [4.10.0](https://github.com/dequelabs/axe-core-gems/compare/v4.9.1...v4.10.0) (2024-08-13)
+
+
+### Features
+
+* Update axe-core to v4.10.0 ([#397](https://github.com/dequelabs/axe-core-gems/issues/397)) ([09e659e](https://github.com/dequelabs/axe-core-gems/commit/09e659ecae87be2b3949d470795c214ad77407ec))
+
+
+### Bug Fixes
+
+* add `Lazy-load Axe::API::Run` to improve boot time ([#396](https://github.com/dequelabs/axe-core-gems/issues/396)) ([f16172e](https://github.com/dequelabs/axe-core-gems/commit/f16172ee3377e05fd08ca9c4fd55649457402cde))
+
 ## [4.9.1](https://github.com/dequelabs/axe-core-gems/compare/v4.9.0...v4.9.1) (2024-05-08)
 
 
diff --git a/package-lock.json b/package-lock.json
index 526e85f6..bff91918 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,15 +1,15 @@
 {
   "name": "axe-core-gems",
-  "version": "4.8.0",
+  "version": "4.9.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "axe-core-gems",
-      "version": "4.8.0",
+      "version": "4.9.0",
       "license": "MPL-2.0",
       "devDependencies": {
-        "axe-test-fixtures": "github:dequelabs/axe-test-fixtures",
+        "axe-test-fixtures": "github:dequelabs/axe-test-fixtures#v1",
         "commit-and-tag-version": "^11.2.4",
         "conventional-changelog-cli": "^2.2.2"
       }
@@ -115,7 +115,7 @@
     },
     "node_modules/axe-test-fixtures": {
       "version": "1.0.0",
-      "resolved": "git+ssh://git@github.com/dequelabs/axe-test-fixtures.git#a8b90ebb4fe63fc76158d231c109d527471e698f",
+      "resolved": "git+ssh://git@github.com/dequelabs/axe-test-fixtures.git#80fde4a947257461a2cc2d3dc746e9381dc59aa0",
       "dev": true,
       "license": "MPL-2.0"
     },
diff --git a/package.json b/package.json
index d898c04e..2d068a4f 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "axe-core-gems",
-  "version": "4.9.1",
+  "version": "4.10.0",
   "license": "MPL-2.0",
   "private": true,
   "repository": {
@@ -11,7 +11,7 @@
     "changelog": "standard-version -a --skip.tag=true --skip.commit=true --skip.bump=true"
   },
   "devDependencies": {
-    "axe-test-fixtures": "github:dequelabs/axe-test-fixtures",
+    "axe-test-fixtures": "github:dequelabs/axe-test-fixtures#v1",
     "commit-and-tag-version": "^11.2.4",
     "conventional-changelog-cli": "^2.2.2"
   }
diff --git a/packages/axe-core-api/e2e/selenium/spec/api_spec.rb b/packages/axe-core-api/e2e/selenium/spec/api_spec.rb
index ee2a78dc..ddfb090f 100644
--- a/packages/axe-core-api/e2e/selenium/spec/api_spec.rb
+++ b/packages/axe-core-api/e2e/selenium/spec/api_spec.rb
@@ -2,10 +2,10 @@
 require "json" #TODO: REMOVE
 require "selenium-webdriver"
 require "axe/core"
-require "axe/api/run"
+require "axe/api"
 
 options = Selenium::WebDriver::Chrome::Options.new
-# options.add_argument('--headless')
+options.add_argument('--headless')
 options.add_argument('--no-sandbox')
 options.add_argument('--disable-dev-shm-usage')
 $driver = Selenium::WebDriver.for :chrome, options: options
diff --git a/packages/axe-core-api/lib/axe/api.rb b/packages/axe-core-api/lib/axe/api.rb
new file mode 100644
index 00000000..75ca0c26
--- /dev/null
+++ b/packages/axe-core-api/lib/axe/api.rb
@@ -0,0 +1,5 @@
+module Axe
+  module API
+    autoload :Run, "axe/api/run"
+  end
+end
diff --git a/packages/axe-core-api/lib/axe/matchers/be_axe_clean.rb b/packages/axe-core-api/lib/axe/matchers/be_axe_clean.rb
index e7065f6d..d7dfc5f3 100644
--- a/packages/axe-core-api/lib/axe/matchers/be_axe_clean.rb
+++ b/packages/axe-core-api/lib/axe/matchers/be_axe_clean.rb
@@ -2,7 +2,7 @@
 
 require_relative "../../chain_mail/chainable"
 require_relative "../core"
-require_relative "../api/run"
+require_relative "../api"
 
 module Axe
   module Matchers
diff --git a/packages/axe-core-api/package-lock.json b/packages/axe-core-api/package-lock.json
index 752a7c20..ab21f26b 100644
--- a/packages/axe-core-api/package-lock.json
+++ b/packages/axe-core-api/package-lock.json
@@ -7,13 +7,13 @@
       "name": "axe-core-api",
       "license": "MPL-2.0",
       "dependencies": {
-        "axe-core": "^4.9.1"
+        "axe-core": "^4.10.0"
       }
     },
     "node_modules/axe-core": {
-      "version": "4.9.1",
-      "resolved": "https://registry.npmjs.org/axe-core/-/axe-core-4.9.1.tgz",
-      "integrity": "sha512-QbUdXJVTpvUTHU7871ppZkdOLBeGUKBQWHkHrvN2V9IQWGMt61zf3B45BtzjxEJzYuj0JBjBZP/hmYS/R9pmAw==",
+      "version": "4.10.0",
+      "resolved": "https://registry.npmjs.org/axe-core/-/axe-core-4.10.0.tgz",
+      "integrity": "sha512-Mr2ZakwQ7XUAjp7pAwQWRhhK8mQQ6JAaNWSjmjxil0R8BPioMtQsTLOolGYkji1rcL++3dCqZA3zWqpT+9Ew6g==",
       "engines": {
         "node": ">=4"
       }
@@ -21,9 +21,9 @@
   },
   "dependencies": {
     "axe-core": {
-      "version": "4.9.1",
-      "resolved": "https://registry.npmjs.org/axe-core/-/axe-core-4.9.1.tgz",
-      "integrity": "sha512-QbUdXJVTpvUTHU7871ppZkdOLBeGUKBQWHkHrvN2V9IQWGMt61zf3B45BtzjxEJzYuj0JBjBZP/hmYS/R9pmAw=="
+      "version": "4.10.0",
+      "resolved": "https://registry.npmjs.org/axe-core/-/axe-core-4.10.0.tgz",
+      "integrity": "sha512-Mr2ZakwQ7XUAjp7pAwQWRhhK8mQQ6JAaNWSjmjxil0R8BPioMtQsTLOolGYkji1rcL++3dCqZA3zWqpT+9Ew6g=="
     }
   }
 }
diff --git a/packages/axe-core-api/package.json b/packages/axe-core-api/package.json
index 62e466ea..7de1fb65 100644
--- a/packages/axe-core-api/package.json
+++ b/packages/axe-core-api/package.json
@@ -2,6 +2,6 @@
   "name": "axe-core-api",
   "license": "MPL-2.0",
   "dependencies": {
-    "axe-core": "^4.9.1"
+    "axe-core": "^4.10.0"
   }
 }
diff --git a/version.rb b/version.rb
index 7467b548..9f24dbc3 100644
--- a/version.rb
+++ b/version.rb
@@ -1,5 +1,5 @@
 # this version is used by all the packages
 
 module AxeCoreGems
-  VERSION = "4.9.1"
+  VERSION = "4.10.0"
 end