diff --git a/lib/better_errors/code_formatter.rb b/lib/better_errors/code_formatter.rb
index 4c6824d1..fea2643f 100644
--- a/lib/better_errors/code_formatter.rb
+++ b/lib/better_errors/code_formatter.rb
@@ -12,12 +12,16 @@ class CodeFormatter
       ".haml" => :haml
     }
 
-    attr_reader :filename, :line, :context
+    attr_reader :filename, :line, :uperlines, :lowerlines
 
-    def initialize(filename, line, context = 5)
-      @filename = filename
-      @line     = line
-      @context  = context
+    def initialize(filename, line, uperlines = nil, lowerlines = nil)
+      @filename   = filename
+      @line       = line
+      @uperlines  = uperlines || line - 5
+      @lowerlines = lowerlines || line + 5
+
+      @uperlines = 1 if begin_of_file_reached?
+      @lowerlines = source_lines.count if end_of_file_reached?
     end
 
     def output
@@ -55,9 +59,15 @@ def source_lines
     end
 
     def line_range
-      min = [line - context, 1].max
-      max = [line + context, source_lines.count].min
-      min..max
+      uperlines..lowerlines
+    end
+
+    def begin_of_file_reached?
+      uperlines <= 1
+    end
+
+    def end_of_file_reached?
+      lowerlines >= source_lines.count
     end
   end
 end
diff --git a/lib/better_errors/code_formatter/html.rb b/lib/better_errors/code_formatter/html.rb
index ec96a214..4a116b59 100644
--- a/lib/better_errors/code_formatter/html.rb
+++ b/lib/better_errors/code_formatter/html.rb
@@ -19,8 +19,40 @@ def formatted_nums
       }
     end
 
+    def diff_expander_icon
+      '<svg aria-hidden="true" class="octicon octicon-unfold" ' \
+           'height="16" version="1.1" viewBox="0 0 14 16" width="14">' \
+        '<path fill-rule="evenodd" d="M11.5 7.5L14 10c0 .55-.45 1-1 ' \
+        '1H9v-1h3.5l-2-2h-7l-2 2H5v1H1c-.55 0-1-.45-1-1l2.5-2.5L0 ' \
+        '5c0-.55.45-1 1-1h4v1H1.5l2 2h7l2-2H9V4h4c.55 0 1 .45 1 ' \
+        '1l-2.5 2.5zM6 6h2V3h2L7 0 4 3h2v3zm2 3H6v3H4l3 3 3-3H8V9z">' \
+        '</path>' \
+      '</svg>'
+    end
+
     def formatted_code
-      %{<div class="code_linenums">#{formatted_nums.join}</div><div class="code">#{super}</div>}
+      code = ''
+
+      if true
+        code << '<span class="diff-expander">' \
+                  "<a href='#' data-direction='up' title='Expand'>" \
+                    "#{diff_expander_icon}" \
+                  "</a>" \
+                '</span>'
+      end
+
+      code << "<div class='code_linenums'>#{formatted_nums.join}</div>"
+      code << "<div class='code'>#{super}</div>"
+
+      if true
+        code << '<span class="diff-expander">' \
+                  "<a href='#' data-direction='down' title='Expand'>" \
+                    "#{diff_expander_icon}" \
+                  "</a>" \
+                '</span>'
+      end
+
+      code
     end
   end
 end
diff --git a/lib/better_errors/error_page.rb b/lib/better_errors/error_page.rb
index 40cccb1c..0102199e 100644
--- a/lib/better_errors/error_page.rb
+++ b/lib/better_errors/error_page.rb
@@ -31,8 +31,7 @@ def render(template_name = "main")
     end
 
     def do_variables(opts)
-      index = opts["index"].to_i
-      @frame = backtrace_frames[index]
+      load_frame_from(opts)
       @var_start_time = Time.now.to_f
       { html: render("variable_info") }
     end
@@ -50,6 +49,16 @@ def do_eval(opts)
       eval_and_respond(index, code)
     end
 
+    def do_diffexpand(opts)
+      load_frame_from(opts)
+
+      @frame.uperlines -= 5 if opts['direction'] == 'up'
+      @frame.lowerlines += 5 if opts['direction'] == 'down'
+
+      @var_start_time = Time.now.to_f
+      { html: render("trace_info") }
+    end
+
     def backtrace_frames
       exception.backtrace
     end
@@ -92,7 +101,8 @@ def request_path
     end
 
     def html_formatted_code_block(frame)
-      CodeFormatter::HTML.new(frame.filename, frame.line).output
+      CodeFormatter::HTML.new(frame.filename, frame.line, frame.uperlines,
+                              frame.lowerlines).output
     end
 
     def text_formatted_code_block(frame)
@@ -138,5 +148,10 @@ def eval_and_respond(index, code)
         result:            result
       }
     end
+
+    def load_frame_from(opts)
+      index = opts["index"].to_i
+      @frame = backtrace_frames[index]
+    end
   end
 end
diff --git a/lib/better_errors/stack_frame.rb b/lib/better_errors/stack_frame.rb
index 46518031..56c78d6c 100644
--- a/lib/better_errors/stack_frame.rb
+++ b/lib/better_errors/stack_frame.rb
@@ -8,12 +8,15 @@ def self.from_exception(exception)
     end
 
     attr_reader :filename, :line, :name, :frame_binding
+    attr_accessor :uperlines, :lowerlines
 
-    def initialize(filename, line, name, frame_binding = nil)
+    def initialize(filename, line, name, frame_binding = nil, uperlines = nil, lowerlines = nil)
       @filename       = filename
       @line           = line
       @name           = name
       @frame_binding  = frame_binding
+      @uperlines      = uperlines || line - 5
+      @lowerlines     = lowerlines || line + 5
 
       set_pretty_method_name if frame_binding
     end
diff --git a/lib/better_errors/templates/main.erb b/lib/better_errors/templates/main.erb
index 81487982..3e3a8160 100644
--- a/lib/better_errors/templates/main.erb
+++ b/lib/better_errors/templates/main.erb
@@ -474,11 +474,23 @@
         float:left;
     }
 
+    .code_block span.diff-expander {
+      display: block;
+      padding: 0 12px;
+      height: 23px;
+    }
+
     .code_linenums span{
         display:block;
         padding:0 12px;
     }
 
+    .code_block span.diff-expander a {
+      position: relative;
+      top: 3px;
+      margin-bottom: 2px;
+    }
+
     .code {
         margin-bottom: -1px;
         border-top-left-radius:2px;
@@ -929,6 +941,33 @@
         if (replInput) replInput.focus();
     }
 
+    function connectDiffExpanders() {
+      var allDiffExpanders = document.querySelectorAll(".diff-expander a");
+      var selectedFrame = document.querySelector("ul.frames li.selected");
+
+      for(var i = 0; i < allDiffExpanders.length; i++) {
+        (function(i, el) {
+          var el = allDiffExpanders[i];
+          el.onclick = function() {
+            var direction = el.getAttribute("data-direction");
+            var index = selectedFrame.getAttribute("data-index");
+            apiCall("diffexpand", { "direction": direction, "index": index }, function(response) {
+                if(response.error) {
+                    el.innerHTML = "<h2 class='error'>" + escapeHTML(response.error) + "</h2>";
+                    if(response.explanation) {
+                      el.innerHTML += "<p class='explanation'>" + escapeHTML(response.explanation) + "</p>";
+                    }
+                    el.innerHTML += "<p><a target='_new' href='https://github.com/charliesome/better_errors'>More about Better Errors</a></p>";
+                } else {
+                  document.querySelector(".code_block").innerHTML = response.html;
+                  connectDiffExpanders();
+                }
+            });
+          }
+        })(i);
+      }
+    }
+
     function selectFrameInfo(index) {
         var el = allFrameInfos[index];
         if(el) {
@@ -947,6 +986,8 @@
                 } else {
                     el.innerHTML = response.html;
 
+                    connectDiffExpanders();
+
                     var repl = el.querySelector(".be-repl .be-console");
                     if(repl) {
                         new REPL(index).install(repl);
diff --git a/lib/better_errors/templates/trace_info.erb b/lib/better_errors/templates/trace_info.erb
new file mode 100644
index 00000000..bc16e370
--- /dev/null
+++ b/lib/better_errors/templates/trace_info.erb
@@ -0,0 +1 @@
+<%== html_formatted_code_block @frame %>