diff --git a/judge/views/user.py b/judge/views/user.py
index 71ac35b..927ece8 100644
--- a/judge/views/user.py
+++ b/judge/views/user.py
@@ -11,6 +11,8 @@ from django.contrib.auth.views import redirect_to_login
 from django.contrib.contenttypes.models import ContentType
 from django.db import transaction
 from django.db.models import Count, Max, Min
+from django.db.models.fields import DateField
+from django.db.models.functions import Cast, ExtractYear
 from django.http import Http404, HttpResponseRedirect, JsonResponse
 from django.shortcuts import get_object_or_404, render
 from django.urls import reverse
@@ -149,6 +151,25 @@ class UserAboutPage(UserPage):
             ratio = (max_ever - max_user) / (max_ever - min_ever) if max_ever != min_ever else 1.0
             context['max_graph'] = max_user + ratio * delta
             context['min_graph'] = min_user + ratio * delta - delta
+
+
+        submissions = (
+            self.object.submission_set
+            .annotate(date_only=Cast('date', DateField()))
+            .values('date_only').annotate(cnt=Count('id'))
+        )
+
+        context['submission_data'] = mark_safe(json.dumps({
+            date_counts['date_only'].isoformat(): date_counts['cnt'] for date_counts in submissions
+        }))
+        context['submission_metadata'] = mark_safe(json.dumps({
+            'min_year': (
+                self.object.submission_set
+                .annotate(year_only=ExtractYear('date'))
+                .aggregate(min_year=Min('year_only'))['min_year']
+            ),
+        }))
+        
         return context
 
     # follow/unfollow user
diff --git a/resources/table.scss b/resources/table.scss
index 5570ff2..dbc8c4a 100644
--- a/resources/table.scss
+++ b/resources/table.scss
@@ -1,7 +1,5 @@
 @import "vars";
 
-$table_header_rounding: 6px;
-
 .table {
     border-spacing: 0;
     width: 100%;
diff --git a/resources/users.scss b/resources/users.scss
index 7e64116..cd189fb 100644
--- a/resources/users.scss
+++ b/resources/users.scss
@@ -1,3 +1,5 @@
+@import "vars";
+
 @media(min-width: 400px) {
     #content-right {
         &.users {
@@ -293,4 +295,101 @@ a.edit-profile {
 }
 .unfollow:hover {
     background: darkred;
+}
+
+#submission-activity {
+    #submission-activity-actions {
+        text-align: center;
+        #prev-year-action, #next-year-action {
+            font-size: 1.75em;
+        }
+        #year {
+            font-size: 1.25em;
+            color: #444;
+        }
+    }
+
+    #submission-activity-display {
+        border: 1px solid $border_gray;
+        border-radius: $table_header_rounding;
+
+        .info-bar {
+            display: flex;
+            justify-content: space-between;
+
+            .info-table {
+                width: 15%;
+                min-width: 130px;
+
+                .info-table-text {
+                    width: 8%;
+                }
+            }
+        }
+
+        .info-text {
+            font-size: 0.75em;
+            line-height: 1;
+            font-weight: 100;
+            color: #444;
+        }
+
+        #submission-total-count {
+            align-self: center;
+            padding-left: 8%;
+            font-size: 0.85em;
+        }
+
+        @media(max-width: 1000px) {
+            #submission-total-count {
+                padding-left: 5px;
+            }
+        }
+
+        table {
+            width: 100%;
+            padding: 5px;
+
+            th.submission-date-col {
+                width: 8%;
+            }
+
+            @media (max-width: 1000px) {
+                th.submission-date-col {
+                    display: none;
+                }
+            }
+            td {
+                border-radius: 20%;
+
+                div {
+                    margin-top: 100%;
+                }
+
+                &.activity-label {
+                    position: relative;
+                    white-space: nowrap;
+                }
+
+                &.activity-blank {
+                    background-color: white;
+                }
+                &.activity-0 {
+                    background-color: #ddd;
+                }
+                &.activity-1 {
+                    background-color: #9be9a8;
+                }
+                &.activity-2 {
+                    background-color: #40c463;
+                }
+                &.activity-3 {
+                    background-color: #2f9c4c;
+                }
+                &.activity-4 {
+                    background-color: #216e39;
+                }
+            }
+        }
+    }
 }
\ No newline at end of file
diff --git a/resources/vars.scss b/resources/vars.scss
index bd43b26..4bcda31 100644
--- a/resources/vars.scss
+++ b/resources/vars.scss
@@ -7,5 +7,6 @@ $announcement_red: #ae0000;
 
 $base_font_size: 14px;
 $widget_border_radius: 4px;
+$table_header_rounding: 6px;
 
 $monospace-fonts: Consolas, "Andale Mono WT", "Andale Mono", "Lucida Console", "Lucida Sans Typewriter", "DejaVu Sans Mono", "Bitstream Vera Sans Mono", "Liberation Mono", "Nimbus Mono L", Monaco, "Courier New", Courier, monospace;
diff --git a/templates/user/user-about.html b/templates/user/user-about.html
index 9a40c04..96740e2 100644
--- a/templates/user/user-about.html
+++ b/templates/user/user-about.html
@@ -59,6 +59,69 @@
             <br>
         {% endif %}
 
+        <h4 id="submission-activity-header"></h4>
+        <div id="submission-activity" style="display: none;">
+            <div id="submission-activity-actions">
+                <a href="javascript:void(0)" id="prev-year-action">&laquo;</a>
+                &nbsp;<span id="year"></span>&nbsp;
+                <a href="javascript:void(0)" id="next-year-action">&raquo;</a>
+            </div>
+            <div id="submission-activity-display">
+                <table id="submission-activity-table">
+                    <tr id="submission-0">
+                        <th class="submission-date-col info-text">
+                            {{ _('Mon') }}
+                        </th>
+                    </tr>
+                    <tr id="submission-1">
+                        <th class="submission-date-col info-text">
+                            {{ _('Tues') }}
+                        </th>
+                    </tr>
+                    <tr id="submission-2">
+                        <th class="submission-date-col info-text">
+                            {{ _('Wed') }}
+                        </th>
+                    </tr>
+                    <tr id="submission-3">
+                        <th class="submission-date-col info-text">
+                            {{ _('Thurs') }}
+                        </th>
+                    </tr>
+                    <tr id="submission-4">
+                        <th class="submission-date-col info-text">
+                            {{ _('Fri') }}
+                        </th>
+                    </tr>
+                    <tr id="submission-5">
+                        <th class="submission-date-col info-text">
+                            {{ _('Sat') }}
+                        </th>
+                    </tr>
+                    <tr id="submission-6">
+                        <th class="submission-date-col info-text">
+                            {{ _('Sun') }}
+                        </th>
+                    </tr>
+                </table>
+                <div class="info-bar">
+                    <span id="submission-total-count" class="info-text">
+                    </span>
+                    <table class="info-table">
+                        <tr>
+                            <th class="info-table-text info-text">{{ _('Less') }}</th>
+                            <td class="activity-0"><div></div></td>
+                            <td class="activity-1"><div></div></td>
+                            <td class="activity-2"><div></div></td>
+                            <td class="activity-3"><div></div></td>
+                            <td class="activity-4"><div></div></td>
+                            <th class="info-table-text info-text">{{ _('More') }}</th>
+                        <tr>
+                    </table>
+                </div>
+            </div>
+        </div>
+
         {% if rating %}
             <h4>Rating History</h4>
             <div id="rating-chart">
@@ -81,10 +144,134 @@
         {% include "mathjax-load.html" %}
     {% endif %}
 
+    <script type="text/javascript">
+        var submission_activity = {{ submission_data }};
+        var metadata = {{ submission_metadata }};
+        const activity_levels = 5; // 5 levels of activity
+
+        $(function () {
+            var active_tooltip = null;
+
+            function display_tooltip(where) {
+                if (active_tooltip !== null) {
+                    active_tooltip.removeClass(['tooltipped', 'tooltipped-e', 'tooltipped-w']).removeAttr('aria-label');
+                }
+                if (where !== null) {
+                    var day_num = parseInt(where.attr('data-day'));
+                    var tooltip_direction = day_num < 183 ? 'tooltipped-e' : 'tooltipped-w';
+                    where.addClass(['tooltipped', tooltip_direction])
+                         .attr('aria-label', where.attr('data-submission-activity'));
+                }
+                active_tooltip = where;
+            }
+
+            function install_tooltips () {
+                display_tooltip(null);
+                $('.activity-label').each(function () {
+                    var link = $(this);
+                    link.hover(
+                        function(e) {
+                            display_tooltip(link);
+                        },
+                        function(e) {
+                            display_tooltip(null);
+                        }
+                    );
+                });
+            }
+
+            var current_year = new Date().getFullYear();
+            var $div = $('#submission-activity');
+
+            function draw_contribution(year) {
+                $div.find('#submission-activity-table td').remove();
+                $div.find('#year').attr('data-year', year);
+                $div.find('#prev-year-action').css('display', year > metadata.min_year ? '' : 'none');
+                $div.find('#next-year-action').css('display', year < current_year ? '' : 'none');
+                var current_weekday = 0;
+                var start_day = new Date(year, 0, 1)
+                var end_day = new Date(year + 1, 0, 0);
+                if (year == current_year) {
+                    end_day = new Date();
+                    start_day = new Date(end_day.getFullYear() - 1, end_day.getMonth(), end_day.getDate() + 1);
+                    $div.find('#year').text("{{ _('past year') }}");
+                } else {
+                    $div.find('#year').text(year);
+                }
+                var days = [];
+                for (var day = start_day, day_num = 1; day <= end_day; day.setDate(day.getDate() + 1), day_num++) {
+                    var isodate = day.toISOString().split('T')[0];
+                    days.push({
+                        date: new Date(day),
+                        weekday: day.getDay(),
+                        day_num: day_num,
+                        activity: submission_activity[isodate] || 0,
+                    });
+                }
+
+                var sum_activity = days.map(obj => obj.activity).reduce((a, b) => a + b, 0);
+                $div.find('#submission-total-count').text(
+                    ngettext("%(cnt)d total submission", "%(cnt)d total submissions", sum_activity)
+                        .replace("%(cnt)d", sum_activity)
+                )
+                if (year == current_year) {
+                    $('#submission-activity-header').text(
+                        ngettext("%(cnt)d submission in the last year", "%(cnt)d submissions in the last year", sum_activity)
+                            .replace("%(cnt)d", sum_activity)
+                    )
+                }
+
+                var max_activity = Math.max.apply(null, days.map(obj => obj.activity));
+                var diff = max_activity / (activity_levels - 1);
+                var activity_breakdown = [...Array(activity_levels).keys()].map(x => diff * x);
+
+                for (; current_weekday < days[0].weekday; current_weekday++) {
+                    $div.find('#submission-' + current_weekday)
+                        .append($('<td>').addClass('activity-blank').append('<div>'));
+                }
+
+                days.forEach(obj => {
+                    var level = activity_breakdown.findIndex(x => x >= obj.activity);
+                    var text =
+                        ngettext("%(cnt)d submission on %(date)s", "%(cnt)d submissions on %(date)s", obj.activity)
+                            .replace('%(cnt)d', obj.activity)
+                            .replace(
+                                '%(date)s',
+                                obj.date.toLocaleDateString(
+                                    "{{ LANGUAGE_CODE }}",
+                                    {month: 'short', year: 'numeric', day: 'numeric'}
+                                )
+                            )
+
+                    $div.find('#submission-' + obj.weekday)
+                        .append(
+                            $('<td>').addClass(['activity-label', 'activity-' + level])
+                                          .attr('data-submission-activity', text)
+                                          .attr('data-day', obj.day_num)
+                                          .append('<div>')
+                        );
+                });
+
+                install_tooltips();
+            }
+
+            $('#prev-year-action').click(function () {
+                draw_contribution(parseInt($div.find('#year').attr('data-year')) - 1);
+            });
+            $('#next-year-action').click(function () {
+                draw_contribution(parseInt($div.find('#year').attr('data-year')) + 1);
+            });
+
+            draw_contribution(current_year);
+            $('#submission-activity').css('display', '');
+        });
+    </script>
+
+
     {% if ratings %}
         <script type="text/javascript" src="{{ static('libs/chart.js/Chart.js') }}"></script>
         <script type="text/javascript">
-            var rating_history = {{rating_data}};
+            var rating_history = {{ rating_data }};
 
             $.each(rating_history, function (index, item) {
                 item.x = new Date(item.timestamp);