diff --git a/Rakefile b/Rakefile
index d69d8900..dbadc2b8 100644
--- a/Rakefile
+++ b/Rakefile
@@ -19,7 +19,7 @@ namespace :demo do
 end
 
 namespace :packages do
-  # TODO: add tests and support for Vite and esbuild
+  # TODO: add tests and support for Vite
   desc "Build & test the Node version of Ruby2JS plus frontend bundling packages"
   task :test do
 
@@ -30,9 +30,7 @@ namespace :packages do
     end
 
     Dir.chdir 'packages/esbuild-plugin' do
-      npm_root = `npm root`.strip
       sh 'yarn install' unless File.exist? 'yarn.lock'
-      sh "cp ../ruby2js/ruby2js.js #{npm_root}/@ruby2js/ruby2js/ruby2js.js"
       sh 'yarn test'
     end
 
diff --git a/demo/ruby2js.rb b/demo/ruby2js.rb
index 5241117f..a1cb36dd 100755
--- a/demo/ruby2js.rb
+++ b/demo/ruby2js.rb
@@ -23,6 +23,7 @@
 require 'ruby2js/demo'
 require 'cgi'
 require 'pathname'
+require 'json'
 
 def parse_request(env=ENV)
 
@@ -57,6 +58,10 @@ def parse_request(env=ENV)
 
   opts.on('--preset', "use sane defaults (modern eslevel & common filters)") {options[:preset] = true}
 
+  opts.on('-C', '--config [FILE]', "configuration file to use (default is config/ruby2js.rb)") {|filename|
+    options[:config_file] = filename
+  }
+
   opts.on('--autoexports [default]', "add export statements for top level constants") {|option|
     options[:autoexports] = option ? option.to_sym : true
   }
@@ -90,6 +95,10 @@ def parse_request(env=ENV)
     selected.push(*names)
   end
 
+  opts.on('--filepath [PATH]', "supply a path if stdin is related to a source file") do |filepath|
+    options[:file] = filepath
+  end
+
   opts.on('--identity', "triple equal comparison operators") {options[:comparison] = :identity}
 
   opts.on('--import_from_skypack', "use Skypack for internal functions import statements") do
@@ -130,6 +139,10 @@ def parse_request(env=ENV)
     options[:underscored_private] = true
   end
 
+  opts.on("--sourcemap", "Provide a JSON object with the code and sourcemap") do
+    @provide_sourcemap = true
+  end
+
   # shameless hack.  Instead of repeating the available options, extract them
   # from the OptionParser.  Exclude default options and es20xx options.
   options_available = opts.instance_variable_get(:@stack).last.list.
@@ -168,9 +181,29 @@ def parse_request(env=ENV)
   # command line support
   if ARGV.length > 0
     options[:file] = ARGV.first
-    puts Ruby2JS.convert(File.read(ARGV.first), options).to_s
+    conv = Ruby2JS.convert(File.read(ARGV.first), options)
+    if @provide_sourcemap
+      puts(
+        {
+          code: conv.to_s,
+          sourcemap: conv.sourcemap,
+        }.to_json
+      )
+    else
+      puts conv.to_s
+    end
   else
-    puts Ruby2JS.convert($stdin.read, options).to_s
+    conv = Ruby2JS.convert($stdin.read, options)
+    if @provide_sourcemap
+      puts(
+        {
+          code: conv.to_s,
+          sourcemap: conv.sourcemap,
+        }.to_json
+      )
+    else
+      puts conv.to_s
+    end
   end  
 
 else
diff --git a/lib/ruby2js.rb b/lib/ruby2js.rb
index 04a11271..f672bd39 100644
--- a/lib/ruby2js.rb
+++ b/lib/ruby2js.rb
@@ -8,6 +8,7 @@
   $VERBOSE = old_verbose
 end
 
+require 'ruby2js/configuration_dsl' unless RUBY_ENGINE == 'opal'
 require 'ruby2js/converter'
 require 'ruby2js/filter'
 require 'ruby2js/namespace'
@@ -68,16 +69,11 @@ class Processor < Parser::AST::Processor
       include Ruby2JS::Filter
       BINARY_OPERATORS = Converter::OPERATORS[2..-1].flatten
 
-      attr_accessor :prepend_list, :disable_autoimports, :namespace
+      attr_accessor :prepend_list, :disable_autoimports, :disable_autoexports, :namespace
 
       def initialize(comments)
         @comments = comments
 
-        # check if magic comment is present:
-        first_comment = @comments.values.first&.map(&:text)&.first
-        @disable_autoimports = first_comment&.include?(" autoimports: false")
-        @disable_autoexports = first_comment&.include?(" autoexports: false")
-
         @ast = nil
         @exclude_methods = []
         @prepend_list = Set.new
@@ -218,18 +214,10 @@ def on_send(node)
     end
   end
 
+  # TODO: this method has gotten long and unwieldy!
   def self.convert(source, options={})
     Filter.autoregister unless RUBY_ENGINE == 'opal'
     options = options.dup
-    if options[:preset]
-      options[:eslevel] ||= @@eslevel_preset_default
-      options[:filters] = Filter::PRESET_FILTERS + Array(options[:filters]).uniq
-      options[:comparison] ||= :identity
-      options[:underscored_private] = true unless options[:underscored_private] == false
-    end
-    options[:eslevel] ||= @@eslevel_default
-    options[:strict] = @@strict_default if options[:strict] == nil
-    options[:module] ||= @@module_default || :esm
 
     if Proc === source
       file,line = source.source_location
@@ -246,11 +234,54 @@ def self.convert(source, options={})
       comments = ast ? Parser::Source::Comment.associate(ast, comments) : {}
     end
 
+    # check if magic comment is present
+    first_comment = comments.values.first&.map(&:text)&.first
+    if first_comment
+      if first_comment.include?(" ruby2js: preset")
+        options[:preset] = true
+        if first_comment.include?("filters: ")
+          options[:filters] = first_comment.match(%r(filters:\s*?([^\s]+)\s?.*$))[1].split(",").map(&:to_sym)
+        end
+        if first_comment.include?("eslevel: ")
+          options[:eslevel] = first_comment.match(%r(eslevel:\s*?([^\s]+)\s?.*$))[1].to_i
+        end
+        if first_comment.include?("disable_filters: ")
+          options[:disable_filters] = first_comment.match(%r(disable_filters:\s*?([^\s]+)\s?.*$))[1].split(",").map(&:to_sym)
+        end
+      end
+      disable_autoimports = first_comment.include?(" autoimports: false")
+      disable_autoexports = first_comment.include?(" autoexports: false")
+    end
+
+    unless RUBY_ENGINE == 'opal'
+      unless options.key?(:config_file) || !File.exist?("config/ruby2js.rb")
+        options[:config_file] ||= "config/ruby2js.rb"
+      end
+
+      if options[:config_file]
+        options = ConfigurationDSL.load_from_file(options[:config_file], options).to_h
+      end
+    end
+
+    if options[:preset]
+      options[:eslevel] ||= @@eslevel_preset_default
+      options[:filters] = Filter::PRESET_FILTERS + Array(options[:filters]).uniq
+      if options[:disable_filters]
+        options[:filters] -= options[:disable_filters]
+      end
+      options[:comparison] ||= :identity
+      options[:underscored_private] = true unless options[:underscored_private] == false
+    end
+    options[:eslevel] ||= @@eslevel_default
+    options[:strict] = @@strict_default if options[:strict] == nil
+    options[:module] ||= @@module_default || :esm
+
     namespace = Namespace.new
 
     filters = Filter.require_filters(options[:filters] || Filter::DEFAULTS)
 
     unless filters.empty?
+      filter_options = options.merge({ filters: filters })
       filters.dup.each do |filter|
         filters = filter.reorder(filters) if filter.respond_to? :reorder
       end
@@ -261,7 +292,9 @@ def self.convert(source, options={})
       end
       filter = filter.new(comments)
 
-      filter.options = options
+      filter.disable_autoimports = disable_autoimports
+      filter.disable_autoexports = disable_autoexports
+      filter.options = filter_options
       filter.namespace = namespace
       ast = filter.process(ast)
 
diff --git a/lib/ruby2js/configuration_dsl.rb b/lib/ruby2js/configuration_dsl.rb
new file mode 100644
index 00000000..e1a0c7a2
--- /dev/null
+++ b/lib/ruby2js/configuration_dsl.rb
@@ -0,0 +1,86 @@
+module Ruby2JS
+  class ConfigurationDSL
+    def self.load_from_file(config_file, options = {})
+      new(options).tap { _1.instance_eval(File.read(config_file), config_file, 1) }
+    end
+
+    def initialize(options = {})
+      @options = options
+    end
+
+    def preset(bool = true)
+      @options[:preset] = bool
+    end
+
+    def filter(name)
+      @options[:filters] ||= []
+      @options[:filters] << name
+    end
+
+    def remove_filter(name)
+      @options[:filters]&.reject! { _1 == name }
+    end
+
+    def eslevel(level)
+      @options[:eslevel] = level
+    end
+
+    def equality_comparison
+      @options[:comparison] = :equality
+    end
+
+    def identity_comparison
+      @options[:comparison] = :identity
+    end
+
+    def esm_modules
+      @options[:module] = :esm
+    end
+
+    def cjs_modules
+      @options[:module] = :cjs
+    end
+
+    def underscored_ivars
+      @options[:underscored_private] = true
+    end
+
+    # Only applies for ES2022+
+    def private_field_ivars
+      @options[:underscored_private] = false
+    end
+
+    def logical_or
+      @options[:or] = :logical
+    end
+
+    def nullish_or
+      @options[:or] = :nullish
+    end
+
+    def use_strict(bool = true)
+      @options[:strict] = bool
+    end
+
+    def autoimport(identifier = nil, file = nil, &block)
+      if block
+        @options[:autoimports] = block
+        return
+      elsif @options[:autoimports].is_a?(Proc)
+        @options[:autoimports] = {}
+      end
+
+      @options[:autoimports] ||= {}
+      @options[:autoimports][identifier] = file
+    end
+
+    def include_method(method_name)
+      @options[:include] ||= []
+      @options[:include] << method_name unless @options[:include].include?(method_name)
+    end
+
+    def to_h
+      @options
+    end
+  end
+end
diff --git a/lib/ruby2js/converter/return.rb b/lib/ruby2js/converter/return.rb
index edf9a9d5..0589868b 100644
--- a/lib/ruby2js/converter/return.rb
+++ b/lib/ruby2js/converter/return.rb
@@ -15,7 +15,7 @@ class Converter
     EXPRESSIONS = [ :array, :float, :hash, :int, :lvar, :nil, :send, :attr,
       :str, :sym, :dstr, :dsym, :cvar, :ivar, :zsuper, :super, :or, :and,
       :block, :const, :true, :false, :xnode, :taglit, :self,
-      :op_asgn, :and_asgn, :or_asgn, :taglit, :gvar, :csend ]
+      :op_asgn, :and_asgn, :or_asgn, :taglit, :gvar, :csend, :call ]
 
     handle :autoreturn do |*statements|
       return if statements == [nil]
diff --git a/lib/ruby2js/filter/camelCase.rb b/lib/ruby2js/filter/camelCase.rb
index 926c5ec8..a7ff72ca 100644
--- a/lib/ruby2js/filter/camelCase.rb
+++ b/lib/ruby2js/filter/camelCase.rb
@@ -132,6 +132,10 @@ def on_sym(node)
         handle_generic_node(super, :sym)
       end
 
+      def on_assign(node)
+        S(:assign , node.children[0], *node.children[1..-1].map{ process _1 })
+      end
+
       def on_defs(node)
         node = super
         return node if node.type != :defs
diff --git a/lib/ruby2js/filter/require.rb b/lib/ruby2js/filter/require.rb
index 6d1214be..a9dd72ed 100644
--- a/lib/ruby2js/filter/require.rb
+++ b/lib/ruby2js/filter/require.rb
@@ -91,6 +91,18 @@ def on_send(node)
                 target << child.children[1]
               elsif child.type == :def
                 target << child.children[0]
+              elsif child.type == :send && child.children[1] == :async
+                target << child.children[2].children[0]
+              elsif child.type == :const
+                target << child.children[1]
+              elsif child.type == :array
+                child.children.each do |export_statement|
+                  if export_statement.type == :const
+                    target << export_statement.children[1]
+                  elsif export_statement.type == :hash
+                    default_exports << export_statement.children[0].children[1].children[1]
+                  end
+                end
               end
             end
 
@@ -99,6 +111,12 @@ def on_send(node)
             else
               named_exports += auto_exports
             end
+            default_exports.map! { _1.to_s.sub(/[?!]/, '').then do |name|
+              respond_to?(:camelCase) ? camelCase(name) : name.to_sym
+            end }
+            named_exports.map! { _1.to_s.sub(/[?!]/, '').then do |name|
+              respond_to?(:camelCase) ? camelCase(name) : name.to_sym
+            end }
 
             imports = @require_seen[realpath]
             imports << s(:const, nil, default_exports.first) unless default_exports.empty?
diff --git a/packages/esbuild-plugin/package.json b/packages/esbuild-plugin/package.json
index edaa59db..464c9328 100644
--- a/packages/esbuild-plugin/package.json
+++ b/packages/esbuild-plugin/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@ruby2js/esbuild-plugin",
-  "version": "0.0.3",
+  "version": "1.0.0",
   "description": "ruby2js plugin for esbuild",
   "contributors": [
     "Jared White",
@@ -28,7 +28,6 @@
     "access": "public"
   },
   "dependencies": {
-    "@ruby2js/ruby2js": ">0.0.1",
     "convert-source-map": "^1.8.0"
   },
   "devDependencies": {
diff --git a/packages/esbuild-plugin/src/index.js b/packages/esbuild-plugin/src/index.js
index 8db22802..c3be01a9 100644
--- a/packages/esbuild-plugin/src/index.js
+++ b/packages/esbuild-plugin/src/index.js
@@ -1,26 +1,70 @@
-const Ruby2JS = require('@ruby2js/ruby2js')
+const path = require("path")
 const convert = require('convert-source-map')
-const path = require('path')
 const fs = require('fs').promises
+const { spawn } = require('child_process');
 
-module.exports = (options = {}) => ({
+const spawnChild = async (source, extraArgs, filepath) => {
+  const child = spawn('bundle', ['exec', 'ruby2js', '--filepath', filepath, ...extraArgs])
+
+  child.stdin.write(source)
+  child.stdin.end()
+
+  let data = "";
+  for await (const chunk of child.stdout) {
+    data += chunk;
+  }
+  let error = "";
+  for await (const chunk of child.stderr) {
+    error += chunk;
+  }
+  const exitCode = await new Promise((resolve, reject) => {
+    child.on('close', resolve);
+  });
+
+  if (exitCode) {
+    throw new Error(`subprocess error exit ${exitCode}, ${data} ${error}`);
+  }
+  return data;
+}
+
+const ruby2js = (options = {}) => ({
   name: 'ruby2js',
   setup(build) {
     if (!options.buildFilter) options.buildFilter = /\.js\.rb$/
+    let extraArgs = []
+    if (typeof options.provideSourceMaps === "undefined") {
+      options.provideSourceMaps = true
+    }
+    if (options.provideSourceMaps) {
+      extraArgs.push("--sourcemap")
+    }
+    if (typeof options.extraArgs !== undefined) {
+      extraArgs = [...extraArgs, ...(options.extraArgs || [])]
+    }
 
     build.onLoad({ filter: options.buildFilter }, async (args) => {
       const code = await fs.readFile(args.path, 'utf8')
-      js = Ruby2JS.convert(code, { ...options, file: args.path })
-      const output = js.toString()
+      let js = await spawnChild(code, extraArgs, args.path)
 
-      const smap = js.sourcemap
-      smap.sourcesContent = [code]
-      smap.sources[0] = path.basename(args.path)
+      if (options.provideSourceMaps) {
+        js = JSON.parse(js)
+        const output = `${js.code}\n`
+        const smap = js.sourcemap
+        smap.sourcesContent = [code]
+        smap.sources[0] = path.basename(args.path)
 
-      return {
-        contents: output + convert.fromObject(smap).toComment(),
-        loader: 'js'
+        return {
+          contents: output + convert.fromObject(smap).toComment(),
+          loader: 'js'
+        }
+      } else {
+        return {
+          contents: js,
+          loader: 'js'
+        }
       }
     })
   },
 })
+
+module.exports = ruby2js
diff --git a/packages/esbuild-plugin/test/esbuild.config.js b/packages/esbuild-plugin/test/esbuild.config.js
index 95a565df..250514dd 100644
--- a/packages/esbuild-plugin/test/esbuild.config.js
+++ b/packages/esbuild-plugin/test/esbuild.config.js
@@ -16,7 +16,7 @@ require("esbuild").build({
   minify,
   plugins: [
     ruby2js({
-      preset: true
+      extraArgs: ["--preset"]
     })
   ],
-}).catch(() => process.exit(1))
\ No newline at end of file
+}).catch(() => process.exit(1))
diff --git a/packages/esbuild-plugin/test/test_esbuild.js b/packages/esbuild-plugin/test/test_esbuild.js
index 956384ed..54a7d37e 100644
--- a/packages/esbuild-plugin/test/test_esbuild.js
+++ b/packages/esbuild-plugin/test/test_esbuild.js
@@ -1,24 +1,28 @@
 const assert = require('assert')
 const fs = require('fs').promises
 
-describe('@ruby2js/esbuild-plugin', function() {
+function timeout(ms) {
+  return new Promise(resolve => setTimeout(resolve, ms));
+}
+
+describe('@ruby2js/esbuild-plugin', function () {
   this.timeout(5000);
 
-  it('runs code through ruby2js', () => {
+  it('runs code through ruby2js', async () => {
     require("./esbuild.config.js")
 
-    setTimeout(async () => {
-      const code = await fs.readFile(
-        "app/assets/builds/application.js",
-        { encoding: "utf-8"}
-      )
+    await timeout(1000)
+
+    const code = await fs.readFile(
+      "app/assets/builds/application.js",
+      { encoding: "utf-8" }
+    )
 
-      assert.strictEqual(
+    assert.strictEqual(
       `(() => {
-        // main.js.rb
-        console.log(parseInt("2A", 16));
-      })();
-      `, code)
-    }, 1000)
+  // main.js.rb
+  console.log(parseInt("2A", 16));
+})();
+`, code)
   })
 })
diff --git a/spec/config/test_ruby2js.rb b/spec/config/test_ruby2js.rb
new file mode 100644
index 00000000..65bf33d0
--- /dev/null
+++ b/spec/config/test_ruby2js.rb
@@ -0,0 +1,17 @@
+preset
+
+filter :camelCase
+filter :lit
+
+eslevel 2022
+
+equality_comparison
+
+nullish_or
+
+use_strict true
+
+autoimport :FooBar, "@org/package/foobar.js"
+
+include_method :class
+include_method :call
diff --git a/spec/configuration_dsl_spec.rb b/spec/configuration_dsl_spec.rb
new file mode 100644
index 00000000..48ad96ab
--- /dev/null
+++ b/spec/configuration_dsl_spec.rb
@@ -0,0 +1,23 @@
+gem 'minitest'
+require 'minitest/autorun'
+require 'ruby2js'
+
+describe Ruby2JS::ConfigurationDSL do
+  
+  def to_js( string)
+    _(Ruby2JS.convert(string, config_file: "spec/config/test_ruby2js.rb").to_s)
+  end
+
+  # random tests just to santity check…see return_spec.rb for the full suite
+  describe "loaded config file" do
+    it "should affect the transpilation" do
+      to_js( 'class C; def self.f_n(x_y); FooBar.(x_y); end; def inst; self.class.f_n(); end; end' ).
+        must_equal '"use strict"; import FooBar from "@org/package/foobar.js"; class C {static fN(xY) {return FooBar(xY)}; get inst() {return this.constructor.fN()}}'
+    end
+
+    it "should support Lit" do
+      to_js( 'class FooElement < LitElement; customElement "foo-bar"; end' ).
+        must_equal '"use strict"; import { LitElement, css, html } from "lit"; class FooElement extends LitElement {}; customElements.define("foo-bar", FooElement)'
+    end
+  end
+end
diff --git a/spec/lit_spec.rb b/spec/lit_spec.rb
index 05280653..03148a97 100644
--- a/spec/lit_spec.rb
+++ b/spec/lit_spec.rb
@@ -15,8 +15,7 @@ def to_js22(string)
   end
   
   def to_js_esm(string)
-    _(Ruby2JS.convert(string, eslevel: 2021,
-      filters: [Ruby2JS::Filter::Lit, Ruby2JS::Filter::ESM]).to_s)
+    _(Ruby2JS.convert(string, eslevel: 2021, filters: [:lit, :esm]).to_s)
   end
 
   describe "properties <= 2021" do
diff --git a/spec/preset_spec.rb b/spec/preset_spec.rb
index ab8b2349..4f499df1 100644
--- a/spec/preset_spec.rb
+++ b/spec/preset_spec.rb
@@ -4,10 +4,14 @@
 
 describe "preset option" do
 
-  def to_js( string)
+  def to_js(string)
     _(Ruby2JS.convert(string, preset: true).to_s)
   end
 
+  def to_js_basic(string)
+    _(Ruby2JS.convert(string).to_s)
+  end
+
   # random tests just to santity check…see return_spec.rb for the full suite
   describe :return do
     it "should handle arrays" do
@@ -43,4 +47,26 @@ def to_js( string)
         must_equal 'class A {b() {this._c = 1; return this._c}}'
     end
   end
+
+  describe :magic_comments do
+    it 'should allow preset option' do
+      to_js_basic( %(# ruby2js: preset\nclass A; def b(); @c = 1; end; end;) ).
+        must_equal %(// ruby2js: preset\nclass A {\n  b() {\n    this._c = 1;\n    return this._c\n  }\n})
+    end
+
+    it 'should allow filters' do
+      to_js_basic( %(# ruby2js: preset, filters: camelCase\nclass A; def b_x(); @c_z = 1; end; end;) ).
+        must_equal %(// ruby2js: preset, filters: camelCase\nclass A {\n  bX() {\n    this._cZ = 1;\n    return this._cZ\n  }\n})
+    end
+
+    it 'should allow eslevel' do
+      to_js_basic( %(# ruby2js: preset, eslevel: 2022\nx.last) ).
+        must_equal %(// ruby2js: preset, eslevel: 2022\nx.at(-1))
+    end
+
+    it 'should allow for disabling filters' do
+      to_js_basic( %(# ruby2js: preset, disable_filters: return\nclass A; def b(); @c = 1; end; end;) ).
+        must_equal %(// ruby2js: preset, disable_filters: return\nclass A {\n  b() {\n    this._c = 1\n  }\n})
+    end
+  end
 end
diff --git a/spec/require/test4.rb b/spec/require/test4.rb
index 766c10fa..d3e11c61 100644
--- a/spec/require/test4.rb
+++ b/spec/require/test4.rb
@@ -1 +1,4 @@
-export Foo = 1
+Foo = 1
+Whoa = 2
+
+export [ Foo, default: Whoa ]
diff --git a/spec/require_spec.rb b/spec/require_spec.rb
index bee35775..5bcbc099 100644
--- a/spec/require_spec.rb
+++ b/spec/require_spec.rb
@@ -77,7 +77,7 @@ def to_js_esm_recursive(string)
   describe :esmimport do
     it "should handle explicit exports" do
       to_js_esm( 'require "require/test4.rb"' ).
-        must_equal 'import { Foo } from "./require/test4.rb"'
+        must_equal 'import Whoa, { Foo } from "./require/test4.rb"'
     end
 
     it "should handle auto exports" do