diff --git a/Gemfile.lock b/Gemfile.lock
index 8aaef74..fed40a6 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -2,6 +2,7 @@ PATH
   remote: .
   specs:
     simplecov-inline (0.1.0)
+      rainbow (~> 3.1)
       simplecov (~> 0.22)
 
 GEM
diff --git a/lib/simplecov/inline.rb b/lib/simplecov/inline.rb
index 51a8089..71cbb1f 100644
--- a/lib/simplecov/inline.rb
+++ b/lib/simplecov/inline.rb
@@ -1,4 +1,5 @@
 require_relative 'inline/version'
+require_relative 'inline/formatter'
 
 module SimpleCov
   module Inline
diff --git a/lib/simplecov/inline/formatter.rb b/lib/simplecov/inline/formatter.rb
new file mode 100644
index 0000000..7eca6a5
--- /dev/null
+++ b/lib/simplecov/inline/formatter.rb
@@ -0,0 +1,101 @@
+require 'rainbow'
+
+module Simplecov
+  module Inline
+    class Formatter
+      Result = Struct.new(:file, :start_line, :end_line, :type) do
+        def to_s
+          lines = [start_line, end_line].uniq.join('-')
+          "#{file}:#{lines} (#{type})"
+        end
+      end
+
+      Config = Struct.new(:files) do
+        def no_output!(reason:)
+          @no_output = reason
+        end
+
+        attr_reader :no_output
+      end
+
+      def self.reset_config = @config = Config.new
+      reset_config
+
+      def self.config(&block)
+        return @config if block.nil?
+
+        block.call(@config)
+
+        return if @config.files.nil?
+
+        @config.files = @config.files.to_set.freeze
+      end
+
+      def format(result, putter: Kernel)
+        missing_coverage = process_files(filtered_files(result:).reject { |file| fully_covered?(file) })
+        success_message = build_success_message(missing_coverage:)
+
+        if success_message
+          putter.puts success_message
+          return
+        end
+
+        putter.puts
+        putter.puts Rainbow('Missing coverage:').yellow
+        putter.puts Rainbow(missing_coverage).yellow
+        putter.puts
+      end
+
+      private
+
+      def build_success_message(missing_coverage:)
+        if self.class.config.no_output
+          return Rainbow("Coverage output skipped. Reason: #{self.class.config.no_output}.").yellow
+        end
+
+        return Rainbow("All branches covered (#{human_filter} files) ✔ ").green if missing_coverage.empty?
+
+        nil
+      end
+
+      def fully_covered?(file)
+        [file.covered_percent, file.branches_coverage_percent].all? { |coverage| coverage == 100 }
+      end
+
+      def human_filter
+        self.class.config.files&.length || 'all'
+      end
+
+      def filtered_files(result:)
+        filter = self.class.config.files
+
+        return result.files if filter.nil?
+
+        result.files.filter { |file| filter.include?(file.filename) }
+      end
+
+      def process_files(files)
+        files.map do |file|
+          [
+            build_line_coverage(file),
+            build_branch_coverage(file),
+          ]
+        end.flatten.compact.join("\n")
+      end
+
+      def build_line_coverage(file)
+        file.missed_lines.map do |uncovered|
+          # uncovered is a SimpleCov::SourceFile::Line
+          Result.new(file.project_filename, uncovered.line_number, uncovered.line_number, 'line')
+        end
+      end
+
+      def build_branch_coverage(file)
+        file.missed_branches.map do |uncovered|
+          # uncovered is a SimpleCov::SourceFile::Branch
+          Result.new(file.project_filename, uncovered.report_line, uncovered.report_line, "branch:#{uncovered.type}")
+        end
+      end
+    end
+  end
+end
diff --git a/simplecov-inline.gemspec b/simplecov-inline.gemspec
index 826f348..bc12038 100644
--- a/simplecov-inline.gemspec
+++ b/simplecov-inline.gemspec
@@ -26,6 +26,7 @@ Gem::Specification.new do |spec|
   spec.executables = spec.files.grep(%r{\Aexe/}) { |f| File.basename(f) }
   spec.require_paths = ['lib']
 
+  spec.add_dependency 'rainbow', '~> 3.1'
   spec.add_dependency 'simplecov', '~> 0.22'
 
   # For more information and examples about making a new gem, check out our
diff --git a/spec/fixtures/file1.rb b/spec/fixtures/file1.rb
new file mode 100644
index 0000000..56fb7f3
--- /dev/null
+++ b/spec/fixtures/file1.rb
@@ -0,0 +1,5 @@
+class File1
+  def method(arg)
+    arg ? 1 : 2
+  end
+end
diff --git a/spec/fixtures/file2.rb b/spec/fixtures/file2.rb
new file mode 100644
index 0000000..691f2aa
--- /dev/null
+++ b/spec/fixtures/file2.rb
@@ -0,0 +1,5 @@
+class File2
+  def method(arg)
+    arg ? 1 : 2
+  end
+end
diff --git a/spec/lib/simplecov/inline/formatter_spec.rb b/spec/lib/simplecov/inline/formatter_spec.rb
new file mode 100644
index 0000000..a574b15
--- /dev/null
+++ b/spec/lib/simplecov/inline/formatter_spec.rb
@@ -0,0 +1,101 @@
+RSpec.describe Simplecov::Inline::Formatter do
+  after { described_class.reset_config }
+
+  describe '#format' do
+    subject { described_class.new.format(result, putter:) }
+
+    let(:putter) { class_double(Kernel) }
+
+    before { allow(putter).to receive(:puts) }
+
+    context 'missing coverage' do
+      let(:result) do
+        SimpleCov::Result.new({
+          File.join(fixture_directory, 'file1.rb') => {
+            # 0 means line 3 is uncovered
+            'lines' => [1, 1, 0, 1, 1],
+            # => 0 means the else branch is uncovered.
+            # 2 is an idenditifier, 3 is the start line, 12 is the start col, 3 is the end line and 14 is the end col.
+            'branches' => {[:if, 0, 3, 4, 3, 8] => {[:then, 1, 3, 8, 3, 10] => 1, [:else, 2, 3, 12, 3, 14] => 0}},
+          },
+        })
+      end
+
+      it 'prints a yellow message saying coverage is missing' do
+        subject
+
+        expect(putter).to have_received(:puts).with(Rainbow('Missing coverage:').yellow)
+      end
+
+      it 'prints the missing lines and branches in yellow' do
+        subject
+
+        expect(putter).to have_received(:puts).with(Rainbow([
+          '/spec/fixtures/file1.rb:3 (line)',
+          '/spec/fixtures/file1.rb:3 (branch:else)',
+        ].join("\n")).yellow)
+      end
+    end
+
+    context 'fully covered' do
+      let(:result) do
+        SimpleCov::Result.new({
+          File.join(fixture_directory, 'file1.rb') => {
+            'lines' => [1, 1, 1, 1, 1],
+            'branches' => {[:if, 0, 3, 4, 3, 8] => {[:then, 1, 3, 8, 3, 10] => 1, [:else, 2, 3, 12, 3, 14] => 1}},
+          },
+        })
+      end
+
+      it 'prints a green message saying fully covered' do
+        subject
+        expect(putter).to have_received(:puts).with(Rainbow('All branches covered (all files) ✔ ').green)
+      end
+    end
+
+    context 'output disabled' do
+      let(:result) { SimpleCov::Result.new({}) }
+
+      before do
+        described_class.config { |config| config.no_output!(reason: 'no output thanks') }
+      end
+
+      it 'prints a yellow message saying output is disabled' do
+        subject
+        expect(putter).to have_received(:puts).with(Rainbow('Coverage output skipped. Reason: no output thanks.').yellow)
+      end
+    end
+
+    context 'filtering out of uncovered files' do
+      let(:result) do
+        SimpleCov::Result.new({
+          File.join(fixture_directory, 'file1.rb') => {'lines' => [1, 1, 1, 1, 1]},
+          File.join(fixture_directory, 'file2.rb') => {'lines' => [1, 1, 0, 1, 1]},
+        })
+      end
+
+      before do
+        described_class.config { |config| config.files = [File.join(fixture_directory, 'file1.rb')]}
+      end
+
+      it 'prints a green message saying fully covered, but notes only 1 file was considered' do
+        subject
+        expect(putter).to have_received(:puts).with(Rainbow('All branches covered (1 files) ✔ ').green)
+      end
+    end
+  end
+
+  describe '.config' do
+    subject { described_class.config }
+
+    it { is_expected.to have_attributes files: nil }
+    it { is_expected.to respond_to :no_output! }
+
+    it 'can change the files' do
+      expect { described_class.config { |config| config.files = ['test.txt'] } }
+        .to change { described_class.config.files }
+        .from(nil)
+        .to(['test.txt'])
+    end
+  end
+end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index bf5ce84..37545e9 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -20,3 +20,5 @@
     c.syntax = :expect
   end
 end
+
+def fixture_directory = @fixture_directory ||= File.join(File.dirname(__FILE__), 'fixtures')