diff --git a/DysonNetwork.Shared/Models/Autocompletion.cs b/DysonNetwork.Shared/Models/Autocompletion.cs
new file mode 100644
index 0000000..6c14fd1
--- /dev/null
+++ b/DysonNetwork.Shared/Models/Autocompletion.cs
@@ -0,0 +1,15 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace DysonNetwork.Shared.Models;
+
+public class AutocompletionRequest
+{
+    [Required] public string Content { get; set; } = null!;
+}
+
+public class Autocompletion
+{
+    public string Type { get; set; } = null!;
+    public string Keyword { get; set; } = null!;
+    public object Data { get; set; } = null!;
+}
\ No newline at end of file
diff --git a/DysonNetwork.Sphere/Autocompletion/AutocompletionService.cs b/DysonNetwork.Sphere/Autocompletion/AutocompletionService.cs
new file mode 100644
index 0000000..10221de
--- /dev/null
+++ b/DysonNetwork.Sphere/Autocompletion/AutocompletionService.cs
@@ -0,0 +1,121 @@
+using Microsoft.EntityFrameworkCore;
+
+namespace DysonNetwork.Sphere.Autocompletion;
+
+public class AutocompletionService(AppDatabase db)
+{
+    public async Task<List<DysonNetwork.Shared.Models.Autocompletion>> GetAutocompletion(string content, int limit = 10)
+    {
+        if (string.IsNullOrWhiteSpace(content))
+            return [];
+
+        if (content.StartsWith('@'))
+        {
+            var afterAt = content[1..];
+            string type;
+            string query;
+            if (afterAt.Contains('/'))
+            {
+                var parts = afterAt.Split('/', 2);
+                type = parts[0];
+                query = parts.Length > 1 ? parts[1] : "";
+            }
+            else
+            {
+                type = "u";
+                query = afterAt;
+            }
+            return await AutocompleteAt(type, query, limit);
+        }
+
+        if (!content.StartsWith(':')) return [];
+        {
+            var query = content[1..];
+            return await AutocompleteSticker(query, limit);
+        }
+
+    }
+
+    private async Task<List<DysonNetwork.Shared.Models.Autocompletion>> AutocompleteAt(string type, string query, int limit)
+    {
+        var results = new List<DysonNetwork.Shared.Models.Autocompletion>();
+
+        switch (type)
+        {
+            case "p":
+                var publishers = await db.Publishers
+                    .Where(p => EF.Functions.Like(p.Name, $"{query}%") || EF.Functions.Like(p.Nick, $"{query}%"))
+                    .Take(limit)
+                    .Select(p => new DysonNetwork.Shared.Models.Autocompletion
+                    {
+                        Type = "publisher",
+                        Keyword = p.Name,
+                        Data = p
+                    })
+                    .ToListAsync();
+                results.AddRange(publishers);
+                break;
+
+            case "r":
+                var realms = await db.Realms
+                    .Where(r => EF.Functions.Like(r.Slug, $"{query}%") || EF.Functions.Like(r.Name, $"{query}%"))
+                    .Take(limit)
+                    .Select(r => new DysonNetwork.Shared.Models.Autocompletion
+                    {
+                        Type = "realm",
+                        Keyword = r.Slug,
+                        Data = r
+                    })
+                    .ToListAsync();
+                results.AddRange(realms);
+                break;
+
+            case "c":
+                var chats = await db.ChatRooms
+                    .Where(c => c.Name != null && EF.Functions.Like(c.Name, $"{query}%"))
+                    .Take(limit)
+                    .Select(c => new DysonNetwork.Shared.Models.Autocompletion
+                    {
+                        Type = "chat",
+                        Keyword = c.Name!,
+                        Data = c
+                    })
+                    .ToListAsync();
+                results.AddRange(chats);
+                break;
+        }
+
+        return results;
+    }
+
+    private async Task<List<DysonNetwork.Shared.Models.Autocompletion>> AutocompleteSticker(string query, int limit)
+    {
+        var stickers = await db.Stickers
+            .Include(s => s.Pack)
+            .Where(s => EF.Functions.Like(s.Slug, $"{query}%"))
+            .Take(limit)
+            .Select(s => new DysonNetwork.Shared.Models.Autocompletion
+            {
+                Type = "sticker",
+                Keyword = s.Slug,
+                Data = s
+            })
+            .ToListAsync();
+
+        // Also possibly search by pack prefix? But user said slug after :
+        // Perhaps combine or search packs
+        var packs = await db.StickerPacks
+            .Where(p => EF.Functions.Like(p.Prefix, $"{query}%"))
+            .Take(limit)
+            .Select(p => new DysonNetwork.Shared.Models.Autocompletion
+            {
+                Type = "sticker_pack",
+                Keyword = p.Prefix,
+                Data = p
+            })
+            .ToListAsync();
+
+        var results = stickers.Concat(packs).Take(limit).ToList();
+        return results;
+    }
+}
diff --git a/DysonNetwork.Sphere/Chat/ChatController.cs b/DysonNetwork.Sphere/Chat/ChatController.cs
index a6f30df..9c7d4f0 100644
--- a/DysonNetwork.Sphere/Chat/ChatController.cs
+++ b/DysonNetwork.Sphere/Chat/ChatController.cs
@@ -4,6 +4,7 @@ using DysonNetwork.Shared.Auth;
 using DysonNetwork.Shared.Data;
 using DysonNetwork.Shared.Models;
 using DysonNetwork.Shared.Proto;
+using DysonNetwork.Sphere.Autocompletion;
 using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.EntityFrameworkCore;
@@ -17,7 +18,8 @@ public partial class ChatController(
     ChatService cs,
     ChatRoomService crs,
     FileService.FileServiceClient files,
-    AccountService.AccountServiceClient accounts
+    AccountService.AccountServiceClient accounts,
+    AutocompletionService aus
 ) : ControllerBase
 {
     public class MarkMessageReadRequest
@@ -329,4 +331,20 @@ public partial class ChatController(
         var response = await cs.GetSyncDataAsync(roomId, request.LastSyncTimestamp);
         return Ok(response);
     }
-}
\ No newline at end of file
+
+    [HttpGet("{roomId:guid}/autocomplete")]
+    public async Task<ActionResult<List<DysonNetwork.Shared.Models.Autocompletion>>> ChatAutoComplete([FromBody] AutocompletionRequest request, Guid roomId)
+    {
+        if (HttpContext.Items["CurrentUser"] is not Account currentUser)
+            return Unauthorized();
+
+        var accountId = Guid.Parse(currentUser.Id);
+        var isMember = await db.ChatMembers
+            .AnyAsync(m => m.AccountId == accountId && m.ChatRoomId == roomId && m.JoinedAt != null && m.LeaveAt == null);
+        if (!isMember)
+            return StatusCode(403, "You are not a member of this chat room.");
+
+        var result = await aus.GetAutocompletion(request.Content, limit: 10);
+        return Ok(result);
+    }
+}
diff --git a/DysonNetwork.Sphere/Startup/ServiceCollectionExtensions.cs b/DysonNetwork.Sphere/Startup/ServiceCollectionExtensions.cs
index 66cd27b..24dcf82 100644
--- a/DysonNetwork.Sphere/Startup/ServiceCollectionExtensions.cs
+++ b/DysonNetwork.Sphere/Startup/ServiceCollectionExtensions.cs
@@ -15,6 +15,7 @@ using System.Text.Json.Serialization;
 using System.Threading.RateLimiting;
 using DysonNetwork.Shared.Cache;
 using DysonNetwork.Shared.GeoIp;
+using DysonNetwork.Sphere.Autocompletion;
 using DysonNetwork.Sphere.WebReader;
 using DysonNetwork.Sphere.Discovery;
 using DysonNetwork.Sphere.Poll;
@@ -118,6 +119,7 @@ public static class ServiceCollectionExtensions
         services.AddScoped<WebFeedService>();
         services.AddScoped<DiscoveryService>();
         services.AddScoped<PollService>();
+        services.AddScoped<AutocompletionService>();
 
         var translationProvider = configuration["Translation:Provider"]?.ToLower();
         switch (translationProvider)
@@ -129,4 +131,4 @@ public static class ServiceCollectionExtensions
 
         return services;
     }
-}
\ No newline at end of file
+}