diff --git a/.gitignore b/.gitignore
index a7126769a4..68b3295238 100644
--- a/.gitignore
+++ b/.gitignore
@@ -20,6 +20,7 @@
 !/storage/.keep
 
 /public/assets
+/public/wasm
 .byebug_history
 
 # Ignore master key for decrypting credentials and more.
diff --git a/app/commands/solution/generate_test_run_config.rb b/app/commands/solution/generate_test_run_config.rb
new file mode 100644
index 0000000000..3dc3202609
--- /dev/null
+++ b/app/commands/solution/generate_test_run_config.rb
@@ -0,0 +1,22 @@
+class Solution::GenerateTestRunConfig
+  include Mandate
+
+  initialize_with :solution
+
+  def call
+    {
+      files: exercise_repo.tooling_files
+    }
+  end
+
+  private
+  memoize
+  def exercise_repo
+    Git::Exercise.new(
+      solution.git_slug,
+      solution.git_type,
+      solution.git_sha,
+      repo_url: solution.track.repo_url
+    )
+  end
+end
diff --git a/app/commands/submission/create.rb b/app/commands/submission/create.rb
index 3de1544102..b43b446232 100644
--- a/app/commands/submission/create.rb
+++ b/app/commands/submission/create.rb
@@ -1,16 +1,15 @@
 class Submission::Create
   include Mandate
 
-  def initialize(solution, files, submitted_via)
+  def initialize(solution, raw_files, submitted_via, test_results_json = nil)
     @submission_uuid = SecureRandom.compact_uuid
-
     @solution = solution
-    @submitted_files = files
     @submitted_via = submitted_via
+    @test_results_json = test_results_json
 
     # TODO: (Optional) - Move this into another service
     # TODO: (Optional) - Consider risks around filenames
-    @submitted_files.each do |f|
+    @submitted_files = raw_files.each do |f|
       f[:digest] = Digest::SHA1.hexdigest(f[:content])
     end
   end
@@ -21,7 +20,7 @@ def call
 
     create_submission!
     create_files!
-    init_test_run!
+    handle_test_run!
     schedule_jobs!
     log_metric!
 
@@ -30,7 +29,7 @@ def call
   end
 
   private
-  attr_reader :solution, :submitted_files, :submission_uuid, :submitted_via, :submission
+  attr_reader :solution, :submitted_files, :submission_uuid, :submitted_via, :submission, :test_results_json
 
   delegate :track, :user, to: :solution
 
@@ -61,8 +60,12 @@ def create_files!
     end
   end
 
-  def init_test_run!
-    Submission::TestRun::Init.(submission)
+  def handle_test_run!
+    if test_results_json
+      Submission::TestRun::ProcessClientSideResults.(submission, test_results_json)
+    else
+      Submission::TestRun::Init.(submission)
+    end
   end
 
   def schedule_jobs!
diff --git a/app/commands/submission/test_run/process.rb b/app/commands/submission/test_run/process.rb
index a840af3dfa..3176629a5c 100644
--- a/app/commands/submission/test_run/process.rb
+++ b/app/commands/submission/test_run/process.rb
@@ -114,9 +114,9 @@ def broadcast!(test_run)
   def results
     res = JSON.parse(tooling_job.execution_output['results.json'], allow_invalid_unicode: true)
     res.is_a?(Hash) ? res.symbolize_keys : {}
-  rescue StandardError => e
-    Bugsnag.notify(e)
-    {}
+    # rescue StandardError => e
+    #   Bugsnag.notify(e)
+    #   {}
   end
 
   memoize
diff --git a/app/commands/submission/test_run/process_client_side_results.rb b/app/commands/submission/test_run/process_client_side_results.rb
new file mode 100644
index 0000000000..c9cfc5851b
--- /dev/null
+++ b/app/commands/submission/test_run/process_client_side_results.rb
@@ -0,0 +1,29 @@
+class Submission::TestRun::ProcessClientSideResults
+  include Mandate
+
+  initialize_with :submission, :test_results_json
+
+  def call
+    Submission::TestRun::Process.(
+      FauxToolingJob.new(submission, test_results_json)
+    )
+  end
+
+  # Rather than rewrite this critical component, for now
+  # we're just stubbing a tooling job as if it had come back
+  # from the server.
+  class FauxToolingJob
+    include Mandate
+
+    initialize_with :submission, :test_results_json do
+      @id = SecureRandom.uuid
+    end
+
+    attr_reader :id
+
+    delegate :uuid, to: :submission, prefix: true
+    def execution_status = 200
+    def source = { "exercise_git_sha" => submission.solution.git_sha }
+    def execution_output = { "results.json" => test_results_json }
+  end
+end
diff --git a/app/controllers/api/solutions/submissions_controller.rb b/app/controllers/api/solutions/submissions_controller.rb
index 2d1ea15203..71f3324cba 100644
--- a/app/controllers/api/solutions/submissions_controller.rb
+++ b/app/controllers/api/solutions/submissions_controller.rb
@@ -16,7 +16,7 @@ def create
 
     # TODO: (Required) Allow rerunning of tests if previous submission was an error / ops error / timeout
     begin
-      submission = Submission::Create.(solution, files, :api)
+      submission = Submission::Create.(solution, files, :api, params[:test_results_json])
     rescue DuplicateSubmissionError
       return render_error(400, :duplicate_submission)
     end
diff --git a/app/helpers/react_components/editor.rb b/app/helpers/react_components/editor.rb
index c25856fd5e..7cba24b335 100644
--- a/app/helpers/react_components/editor.rb
+++ b/app/helpers/react_components/editor.rb
@@ -75,7 +75,8 @@ def data
           icon_url: track.icon_url,
           median_wait_time: track.median_wait_time
         },
-        show_deep_dive_video: show_deep_dive_video?
+        show_deep_dive_video: show_deep_dive_video?,
+        local_test_runner:
       }
     end
 
@@ -102,6 +103,12 @@ def show_deep_dive_video?
       true
     end
 
+    def local_test_runner
+      return nil unless track.slug == "javascript"
+
+      Solution::GenerateTestRunConfig.(solution)
+    end
+
     def mark_video_as_seen_endpoint
       return nil if solution.user.watched_video?(:youtube, exercise.deep_dive_youtube_id)
 
diff --git a/app/javascript/components/Editor.tsx b/app/javascript/components/Editor.tsx
index 382d969d6b..d533a36d07 100644
--- a/app/javascript/components/Editor.tsx
+++ b/app/javascript/components/Editor.tsx
@@ -52,6 +52,7 @@ import {
 import { RealtimeFeedbackModal } from './modals'
 import { ChatGptTab } from './editor/ChatGptFeedback/ChatGptTab'
 import { ChatGptPanel } from './editor/ChatGptFeedback/ChatGptPanel'
+import { runTestsClientSide } from './editor/ClientSideTestRunner/generalTestRunner'
 
 export type TabIndex =
   | 'instructions'
@@ -127,7 +128,9 @@ export default ({
     current: submission,
     set: setSubmission,
     remove: removeSubmission,
-  } = useSubmissionsList(defaultSubmissions, { create: links.runTests })
+  } = useSubmissionsList(defaultSubmissions, {
+    create: links.runTests,
+  })
   const { revertToExerciseStart, revertToLastIteration } = useFileRevert()
   const { create: createIteration } = useIteration()
   const { get: getFiles, set: setFiles } = useEditorFiles({
@@ -162,44 +165,50 @@ export default ({
     else setIsProcessing(false)
   }, [status, testRunStatus])
 
-  const runTests = useCallback(() => {
+  const runTests = useCallback(async () => {
     dispatch({ status: EditorStatus.CREATING_SUBMISSION })
 
-    createSubmission(files, {
-      onSuccess: () => {
-        dispatch({ status: EditorStatus.INITIALIZED })
-        setSubmissionFiles(files)
-        setHasLatestIteration(false)
-      },
-      onError: async (error) => {
-        let editorError: null | Promise<{ type: string; message: string }> =
-          null
+    const testResults = await runTestsClientSide(files)
 
-        if (error instanceof Error) {
-          editorError = Promise.resolve({
-            type: 'unknown',
-            message: 'Unable to submit file. Please try again.',
-          })
-        } else if (error instanceof Response) {
-          editorError = error
-            .json()
-            .then((json) => json.error)
-            .catch(() => {
-              return {
-                type: 'unknown',
-                message: 'Unable to submit file. Please try again.',
-              }
+    createSubmission(
+      { files, testResults },
+      {
+        onSuccess: () => {
+          console.log('SUCCESS')
+          dispatch({ status: EditorStatus.INITIALIZED })
+          setSubmissionFiles(files)
+          setHasLatestIteration(false)
+        },
+        onError: async (error) => {
+          let editorError: null | Promise<{ type: string; message: string }> =
+            null
+
+          if (error instanceof Error) {
+            editorError = Promise.resolve({
+              type: 'unknown',
+              message: 'Unable to submit file. Please try again.',
             })
-        }
+          } else if (error instanceof Response) {
+            editorError = error
+              .json()
+              .then((json) => json.error)
+              .catch(() => {
+                return {
+                  type: 'unknown',
+                  message: 'Unable to submit file. Please try again.',
+                }
+              })
+          }
 
-        if (editorError) {
-          dispatch({
-            status: EditorStatus.CREATE_SUBMISSION_FAILED,
-            error: await editorError,
-          })
-        }
-      },
-    })
+          if (editorError) {
+            dispatch({
+              status: EditorStatus.CREATE_SUBMISSION_FAILED,
+              error: await editorError,
+            })
+          }
+        },
+      }
+    )
   }, [createSubmission, dispatch, files])
 
   const showFeedbackModal = useCallback(() => {
diff --git a/app/javascript/components/editor/ClientSideTestRunner/generalTestRunner.ts b/app/javascript/components/editor/ClientSideTestRunner/generalTestRunner.ts
new file mode 100644
index 0000000000..efb6818643
--- /dev/null
+++ b/app/javascript/components/editor/ClientSideTestRunner/generalTestRunner.ts
@@ -0,0 +1,20 @@
+import { File } from '../../types'
+import { runJsTests } from './jsTestRunner'
+import { runRubyTests } from './rubyTestRunner'
+
+export async function runTestsClientSide(files: File[]) {
+  const solutionFile = files[0]
+
+  const fileExtension = solutionFile.filename.split('.').pop()
+
+  switch (fileExtension) {
+    case 'js':
+      return runJsTests()
+
+    case 'rb':
+      return await runRubyTests()
+
+    default:
+      return null
+  }
+}
diff --git a/app/javascript/components/editor/ClientSideTestRunner/jsTestRunner.ts b/app/javascript/components/editor/ClientSideTestRunner/jsTestRunner.ts
new file mode 100644
index 0000000000..de27d5485d
--- /dev/null
+++ b/app/javascript/components/editor/ClientSideTestRunner/jsTestRunner.ts
@@ -0,0 +1,34 @@
+export function runJsTests() {
+  // run tests here with the js test-runner from npm and return results
+
+  return TEST_RESULTS
+}
+
+const TEST_RESULTS = {
+  version: 3,
+  status: 'pass',
+  message: null,
+  messageHtml: null,
+  output: null,
+  outputHtml: null,
+  tests: [
+    {
+      name: 'Hello World > Say Hi!',
+      status: 'pass',
+      testCode: "expect(hello()).toEqual('Hello, World!');",
+      message:
+        'Error: \u001b[2mexpect(\u001b[22m\u001b[31mreceived\u001b[39m\u001b[2m).\u001b[22mtoEqual\u001b[2m(\u001b[22m\u001b[32mexpected\u001b[39m\u001b[2m) // deep equality\u001b[22m\n\nExpected: \u001b[32m"\u001b[7mHello, World\u001b[27m!"\u001b[39m\nReceived: \u001b[31m"\u001b[7mGoodbye, Mars\u001b[27m!"\u001b[39m',
+      messageHtml:
+        "Error: expect(<span style='color:#A00;'>received</span>).toEqual(<span style='color:#0A0;'>expected</span>) // deep equality\n\nExpected: <span style='color:#0A0;'>&quot;Hello, World!&quot;</span>\nReceived: <span style='color:#A00;'>&quot;Goodbye, Mars!&quot;</span>",
+      expected: null,
+      output: null,
+      outputHtml: null,
+      taskId: null,
+    },
+  ],
+  tasks: [],
+  highlightjsLanguage: 'javascript',
+  links: {
+    self: 'http://local.exercism.io:3020/api/v2/solutions/b714573e50244417a0812ca49cc76a1d/submissions/71487f490f584bfaa61a0051bd244932/test_run',
+  },
+}
diff --git a/app/javascript/components/editor/ClientSideTestRunner/rubyTestRunner.ts b/app/javascript/components/editor/ClientSideTestRunner/rubyTestRunner.ts
new file mode 100644
index 0000000000..4ba397a25c
--- /dev/null
+++ b/app/javascript/components/editor/ClientSideTestRunner/rubyTestRunner.ts
@@ -0,0 +1,51 @@
+import { DefaultRubyVM } from '@ruby/wasm-wasi/dist/browser'
+
+export async function runRubyTests() {
+  const response = await fetch('/wasm/ruby/ruby+stdlib.wasm')
+  const module = await WebAssembly.compileStreaming(response)
+
+  const { vm } = await DefaultRubyVM(module)
+
+  globalThis.RUBY_TEST_RESULTS = null
+  exec(vm)
+
+  console.log('RES', globalThis.RUBY_TEST_RESULTS)
+  return globalThis.RUBY_TEST_RESULTS
+}
+
+function exec(vm) {
+  vm.eval(`
+    require "js"
+    JS.global[:console].log("HERE!!!")
+
+    result = {
+      version: 3,
+      status: 'pass',
+      message: nil,
+      messageHtml: nil,
+      output: nil,
+      outputHtml: nil,
+      tests: [
+        {
+          name: 'Hello World > Say Hi!',
+          status: 'pass',
+          testCode: "expect(hello()).toEqual('Hello, World!');",
+          message:
+            'Error: \u001b[2mexpect(\u001b[22m\u001b[31mreceived\u001b[39m\u001b[2m).\u001b[22mtoEqual\u001b[2m(\u001b[22m\u001b[32mexpected\u001b[39m\u001b[2m) // deep equality\u001b[22m\n\nExpected: \u001b[32m"\u001b[7mHello, World\u001b[27m!"\u001b[39m\nReceived: \u001b[31m"\u001b[7mGoodbye, Mars\u001b[27m!"\u001b[39m',
+          messageHtml:
+            "Error: expect(<span style='color:#A00;'>received</span>).toEqual(<span style='color:#0A0;'>expected</span>) // deep equality\n\nExpected: <span style='color:#0A0;'>&quot;Hello, World!&quot;</span>\nReceived: <span style='color:#A00;'>&quot;Goodbye, Mars!&quot;</span>",
+          expected: nil,
+          output: nil,
+          outputHtml: nil,
+          taskId: nil,
+        },
+      ],
+      tasks: [],
+      highlightjsLanguage: 'javascript',
+      links: {
+        self: 'http://local.exercism.io:3020/api/v2/solutions/b714573e50244417a0812ca49cc76a1d/submissions/71487f490f584bfaa61a0051bd244932/test_run',
+      },
+    }
+    JS.global["RUBY_TEST_RESULTS"] = result
+  `)
+}
diff --git a/app/javascript/components/editor/useSubmissionsList.ts b/app/javascript/components/editor/useSubmissionsList.ts
index 557e1b334a..bb85337750 100644
--- a/app/javascript/components/editor/useSubmissionsList.ts
+++ b/app/javascript/components/editor/useSubmissionsList.ts
@@ -9,13 +9,18 @@ type Links = {
   create: string
 }
 
+type CreateSubmissionParams = {
+  files: File[]
+  testResults: Object | null
+}
+
 export const useSubmissionsList = (
   defaultList: readonly Submission[],
   links: Links
 ): {
   current: Submission | null
   create: (
-    files: File[],
+    params: CreateSubmissionParams,
     config?: { onSuccess: () => void; onError: (error: unknown) => void }
   ) => void
   set: (uuid: string, data: Submission) => void
@@ -23,12 +28,18 @@ export const useSubmissionsList = (
 } => {
   const [list, setList] = useState(defaultList)
 
-  const { mutate: create } = useMutation<Submission, unknown, File[]>(
-    async (files) => {
+  const { mutate: create } = useMutation<
+    Submission,
+    unknown,
+    CreateSubmissionParams
+  >(
+    async ({ files, testResults }) => {
+      const testResultsJson = testResults ? JSON.stringify(testResults) : null
+      console.log('Creating submission with files:', files, testResultsJson)
       const { fetch } = sendRequest({
         endpoint: links.create,
         method: 'POST',
-        body: JSON.stringify({ files: files }),
+        body: JSON.stringify({ files, test_results_json: testResultsJson }),
       })
 
       return fetch.then((response) =>
diff --git a/package.json b/package.json
index 3e9a822cb4..44bff9ca54 100644
--- a/package.json
+++ b/package.json
@@ -40,6 +40,8 @@
     "@popperjs/core": "^2.11.8",
     "@rails/actioncable": "^6.0.0",
     "@replit/codemirror-interact": "^6.3.1",
+    "@ruby/3.4-wasm-wasi": "^2.7.1",
+    "@ruby/wasm-wasi": "^2.7.1",
     "@sector-labs/postcss-inline-class": "^0.0.6",
     "@stripe/react-stripe-js": "^2.1.1",
     "@stripe/stripe-js": "^1.54.1",
@@ -211,7 +213,8 @@
     "test": "jest",
     "test-watch": "jest --watchAll",
     "build:css": "postcss ./app/css/packs/**/*.css --dir .built-assets",
-    "build": "./app/javascript/esbuild.js",
+    "copy:wasm": "node ./scripts/wasm/ruby.js",
+    "build": "yarn copy:wasm && ./app/javascript/esbuild.js",
     "prepare": "husky install"
   },
   "resolutions": {
diff --git a/scripts/wasm/ruby.js b/scripts/wasm/ruby.js
new file mode 100644
index 0000000000..3b4c994c78
--- /dev/null
+++ b/scripts/wasm/ruby.js
@@ -0,0 +1,16 @@
+const fs = require('fs')
+const path = require('path')
+
+const src = path.resolve(
+  __dirname, // this is scripts/wasm/
+  '../../node_modules/@ruby/3.4-wasm-wasi/dist/ruby+stdlib.wasm'
+)
+const destDir = path.resolve(__dirname, '../../public/wasm/ruby')
+const dest = path.join(destDir, 'ruby+stdlib.wasm')
+
+if (!fs.existsSync(destDir)) {
+  fs.mkdirSync(destDir, { recursive: true })
+}
+
+fs.copyFileSync(src, dest)
+console.log('✅ Copied ruby+stdlib.wasm to public/wasm/ruby/')
diff --git a/test/commands/submission/create_test.rb b/test/commands/submission/create_test.rb
index 6e82786097..628a8461a2 100644
--- a/test/commands/submission/create_test.rb
+++ b/test/commands/submission/create_test.rb
@@ -110,4 +110,25 @@ class Submission::CreateTest < ActiveSupport::TestCase
     assert_equal solution.track, metric.track
     assert_equal solution.user, metric.user
   end
+
+  test "processes test run if it's passed and doesn't create new one" do
+    test_results_json = { "foo": "bar" }.to_json
+    solution = create :concept_solution
+
+    files = [{ filename: "subdir/foobar.rb", content: "'I think' = 'I am'" }]
+
+    test_run_id = SecureRandom.uuid
+    submission_uuid = SecureRandom.uuid
+    SecureRandom.stubs(uuid: test_run_id)
+    SecureRandom.stubs(compact_uuid: submission_uuid)
+    Submission::TestRun::Init.expects(:call).never
+    Submission::TestRun::Process.expects(:call).with do |tooling_job|
+      assert_equal test_run_id, tooling_job.id
+      assert_equal submission_uuid, tooling_job.submission_uuid
+      assert_equal 200, tooling_job.execution_status
+      assert_equal({ "exercise_git_sha": solution.git_sha }, tooling_job.source)
+      assert_equal({ "results.json": test_results_json }, tooling_job.execution_output)
+    end
+    Submission::Create.(solution, files, :api, test_results_json)
+  end
 end
diff --git a/test/controllers/api/solutions/submissions_controller_test.rb b/test/controllers/api/solutions/submissions_controller_test.rb
index 486aa9b1db..f40cd38175 100644
--- a/test/controllers/api/solutions/submissions_controller_test.rb
+++ b/test/controllers/api/solutions/submissions_controller_test.rb
@@ -66,7 +66,7 @@ class API::Solutions::SubmissionsControllerTest < API::BaseTestCase
       { filename: "foo", content: "bar" },
       { filename: "bar", content: "foo" }
     ]
-    Submission::Create.expects(:call).with(solution, files, :api).returns(create(:submission))
+    Submission::Create.expects(:call).with(solution, files, :api, nil).returns(create(:submission))
 
     post api_solution_submissions_path(solution.uuid),
       params: { files: },
@@ -76,6 +76,25 @@ class API::Solutions::SubmissionsControllerTest < API::BaseTestCase
     assert_response :created
   end
 
+  test "create should proxy test results" do
+    setup_user
+    solution = create :concept_solution, user: @current_user
+
+    files = [
+      { filename: "foo", content: "bar" },
+      { filename: "bar", content: "foo" }
+    ]
+    test_results_json = { "foo": "bar" }.to_json
+    Submission::Create.expects(:call).with(solution, files, :api, test_results_json).returns(create(:submission))
+
+    post api_solution_submissions_path(solution.uuid, test_results_json:),
+      params: { files: },
+      headers: @headers,
+      as: :json
+
+    assert_response :created
+  end
+
   test "create is rate limited" do
     setup_user
 
diff --git a/yarn.lock b/yarn.lock
index ec643ccc40..e7660f0c88 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1050,6 +1050,11 @@
   resolved "https://registry.yarnpkg.com/@bcoe/v8-coverage/-/v8-coverage-0.2.3.tgz#75a2e8b51cb758a7553d6804a5932d7aace75c39"
   integrity sha512-0hYQ8SB4Db5zvZB4axdMHGwEaQjkZzFjQiN9LVYvIFB2nSUHW9tYpxWriPrWDASIxiaXax83REcLxuSdnGPZtw==
 
+"@bjorn3/browser_wasi_shim@^0.3.0":
+  version "0.3.0"
+  resolved "https://registry.yarnpkg.com/@bjorn3/browser_wasi_shim/-/browser_wasi_shim-0.3.0.tgz#8aa310eed2298bab435bd1f73ab100fbc3f018da"
+  integrity sha512-FlRBYttPRLcWORzBe6g8nmYTafBkOEFeOqMYM4tAHJzFsQy4+xJA94z85a9BCs8S+Uzfh9LrkpII7DXr2iUVFg==
+
 "@bugsnag/browser@^7.25.0":
   version "7.25.0"
   resolved "https://registry.yarnpkg.com/@bugsnag/browser/-/browser-7.25.0.tgz#aa56a8e138dfff268ac29c5fe374cfc3c9b42a76"
@@ -2055,6 +2060,21 @@
   dependencies:
     "@codemirror/state" "^6.2.1"
 
+"@ruby/3.4-wasm-wasi@^2.7.1":
+  version "2.7.1"
+  resolved "https://registry.yarnpkg.com/@ruby/3.4-wasm-wasi/-/3.4-wasm-wasi-2.7.1.tgz#4c42ed6521982b1ae2cde8ca0b7c870cc6d814d8"
+  integrity sha512-uPRvWNL0eR3nYV1iiuJ/QBREUCqc3QKQIJw1iDmuLjiWsftqPfLxN6t0cEtF5mOGh90EZG/NptJoJ4SlJrfzHw==
+  dependencies:
+    "@ruby/wasm-wasi" "^2.0.0"
+
+"@ruby/wasm-wasi@^2.0.0", "@ruby/wasm-wasi@^2.7.1":
+  version "2.7.1"
+  resolved "https://registry.yarnpkg.com/@ruby/wasm-wasi/-/wasm-wasi-2.7.1.tgz#72816add3dd665e6c6bcb39b69567f76b4c28ccb"
+  integrity sha512-2f4NqiJuFoeYiXNr60PH3TbH5c+z/xP2Hq36Av2yahp05AaLDyJxWZwr9EGmfoFsmVTmeDdEW2KjPTfpue6xeg==
+  dependencies:
+    "@bjorn3/browser_wasi_shim" "^0.3.0"
+    tslib "^2.8.1"
+
 "@sector-labs/postcss-inline-class@^0.0.6":
   version "0.0.6"
   resolved "https://registry.yarnpkg.com/@sector-labs/postcss-inline-class/-/postcss-inline-class-0.0.6.tgz#b88965715d6eed5b079df31b33ee66d212fb5cd6"