diff --git a/YaeBlog.Core/Services/EssayContentService.cs b/YaeBlog.Core/Services/EssayContentService.cs
index 472126b..5ae56b5 100644
--- a/YaeBlog.Core/Services/EssayContentService.cs
+++ b/YaeBlog.Core/Services/EssayContentService.cs
@@ -7,6 +7,8 @@ public class EssayContentService
 {
     private readonly ConcurrentDictionary<string, BlogEssay> _essays = new();
 
+    private readonly Dictionary<string, List<BlogEssay>> _tags = [];
+
     public bool TryGet(string key, out BlogEssay? essay)
         => _essays.TryGetValue(key, out essay);
 
@@ -15,4 +17,35 @@ public class EssayContentService
     public IEnumerable<KeyValuePair<string, BlogEssay>> Essays => _essays;
 
     public int Count => _essays.Count;
+
+    public void RefreshTags()
+    {
+        foreach (BlogEssay essay in _essays.Values)
+        {
+            foreach (string tag in essay.Tags)
+            {
+                if (_tags.TryGetValue(tag, out var list))
+                {
+                    list.Add(essay);
+                }
+                else
+                {
+                    _tags[tag] = [essay];
+                }
+            }
+        }
+    }
+
+    public IEnumerable<KeyValuePair<string, int>> Tags => from item in _tags
+        select KeyValuePair.Create(item.Key, item.Value.Count);
+
+    public IEnumerable<BlogEssay> GetTag(string tag)
+    {
+        if (_tags.TryGetValue(tag, out var list))
+        {
+            return list;
+        }
+
+        throw new KeyNotFoundException("Selected tag not found.");
+    }
 }
diff --git a/YaeBlog.Core/Services/RendererService.cs b/YaeBlog.Core/Services/RendererService.cs
index 20c377e..e5fde22 100644
--- a/YaeBlog.Core/Services/RendererService.cs
+++ b/YaeBlog.Core/Services/RendererService.cs
@@ -66,6 +66,7 @@ public class RendererService(ILogger<RendererService> logger,
         });
 
         await PostProcess(postProcessEssays);
+        essayContentService.RefreshTags();
 
         _stopwatch.Stop();
         logger.LogInformation("Render finished, consuming {} s.",