Godot Download Manager

YourLoadingScene
├── DownloadProgress              ← Orchestrator
│   ├── DownloadGroup             ← Group: "Sound Effects"
│   └── DownloadGroup             ← Group: "Music"
└── CanvasLayer
    └── (your UI: ProgressBar, Labels, Button, …)

@onready var dl: DownloadProgress = $DownloadProgress

func _ready() -> void:
    dl.check_completed.connect(_on_check)
    dl.group_progress.connect(_on_progress)
    dl.all_completed.connect(_on_done)

func _on_check(needs_download: bool, bytes: int) -> void:
    if needs_download:
        $UpdateButton.visible = true           # prompt the player
    # else: all_completed fires automatically

func _on_progress(gname: String, idx: int, count: int, dl_bytes: int, total: int) -> void:
    $Bar.value = float(dl_bytes) / total * 100.0 if total > 0 else 0

func _on_done(success: bool) -> void:
    get_tree().change_scene_to_file("res://main_menu.tscn")

var id: int = DLClient.download_file(
	"https://cdn.example.com/maps/arena.bin",
	"user://maps/arena.bin",
	2097152,
	"a1b2c3d4..."
)

DLClient.download_completed.connect(func(did: int, success: bool) -> void:
	if did == id and success:
		load_map("user://maps/arena.bin")
)

var id: int = DLClient.download_json(
	"https://cdn.example.com/dlc/pack2.json",
	"user://dlc/pack2/"
)

DLClient.download_progress.connect(func(did: int, dl: int, total: int) -> void:
	if did == id and total > 0:
		print("%.0f%%" % [float(dl) / total * 100])
)

DLClient.download_completed.connect(func(did: int, success: bool) -> void:
	if did == id:
		print("DLC: " + ("OK" if success else "Failed"))
)

# Call anytime to check status
var info: Dictionary = DLClient.get_progress(some_id)
print(info)  # {"dl": 524288, "total": 1048576, "done": false}

if DLClient.is_file_downloaded("user://maps/arena.bin"):
	load_map("user://maps/arena.bin")
else:
	DLClient.download_file("https://cdn.example.com/maps/arena.bin", "user://maps/arena.bin")

# Check if the cached file matches expected size and hash before using it
if DLClient.is_file_valid("user://maps/arena.bin", 2097152, "a1b2c3d4..."):
	load_map("user://maps/arena.bin")
else:
	# File missing, wrong size, or corrupted — re-download
	DLClient.download_file(
		"https://cdn.example.com/maps/arena.bin",
		"user://maps/arena.bin",
		2097152,
		"a1b2c3d4..."
	)

[
	{"url": "https://cdn.example.com/audio/bgm.mp3", "size": 5938337, "hash": "c39d..."},
	{"url": "https://cdn.example.com/audio/click.mp3", "size": 3632}
]

{
	"version": 1,
	"files": [
		{"url": "https://cdn.example.com/audio/bgm.mp3", "size": 5938337, "hash": "c39d..."},
		{"url": "https://cdn.example.com/audio/click.mp3", "size": 3632, "hash": "82dc..."}
	]
}

_ready()
  │
  ▼
check() — resolves all manifests, checks cache (background thread)
  │
  ├─ All files cached
  │    → check_completed(false, 0)
  │    → all_completed(true)
  │    → Enter game immediately
  │
  └─ Some files need downloading
	   → check_completed(true, download_bytes)
	   → Show update prompt to user
	   → User presses button → start()
	   → Download begins

DownloadProgress (base_folder = "user://game_data/")
├── DownloadGroup (subfolder = "audio/sfx")      ← 2 files
├── DownloadGroup (subfolder = "audio/music")     ← 1 file
└── DownloadGroup (subfolder = "models")          ← 3 files

user://game_data/
├── audio/
│   ├── sfx/
│   │   ├── click.mp3
│   │   └── hover.mp3
│   └── music/
│       └── bgm.mp3
└── models/
	├── character.glb
	├── weapon.glb
	└── environment.glb

start()
  │
  ▼
Group 1: Resolve manifest → Enqueue tasks → Thread pool downloads
  │
  ├── group_progress (every frame)
  ├── file_started (per file)
  │
  ▼
Group 1 finished
  │
  ├── group_completed
  │
  ▼
Group 2: Resolve → Enqueue → Download
  │
  ├── group_progress
  │
  ▼
Group 2 finished → group_completed
  │
  ▼
All groups done → all_completed

check()                       ← runs automatically on _ready()
  │
  ▼
Background thread: resolve all manifests, check cache for every file
  │
  ├── All cached → check_completed(false, 0) → all_completed(true)
  │
  └── Needs download → check_completed(true, total_bytes)
                          │
                          ▼
                     User clicks "Update"
                          │
                          ▼
                       start() → same flow as auto_start=true

addons/download_manager/
├── plugin.cfg                          # Plugin metadata (name, version, entry script)
├── plugin.gd                           # EditorPlugin — registers DLClient autoload
├── download_client.gd                  # Autoload singleton for runtime downloads
├── core/
│   ├── http_util.gd                    # Shared: URL parsing, JSON parsing, blocking HTTP fetch
│   ├── download_task.gd                # Thread-safe data container for a single file
│   ├── download_worker.gd              # HTTP download logic (runs in worker threads)
│   └── thread_pool.gd                  # Thread pool with semaphore-based queue
├── nodes/
│   ├── download_progress.gd            # Orchestrator node for loading screens
│   └── download_group.gd               # Manifest-backed group of files
└── demo/
    ├── demo_scene.tscn                 # Example scene with UI and download groups
    ├── demo_scene.gd                   # Example script with signal handling
    └── manifests/
        ├── sfx_manifest.json           # Sample SFX manifest
        └── music_manifest.json         # Sample music manifest

func _ready() -> void:
    $DownloadProgress.auto_start = true
    $DownloadProgress.all_completed.connect(func(ok: bool) -> void:
        if ok: get_tree().change_scene_to_file("res://game.tscn")
    )

@onready var dl: DownloadProgress = $DownloadProgress
@onready var btn: Button = $UpdateButton

func _ready() -> void:
    btn.visible = false
    dl.check_completed.connect(func(needs: bool, bytes: int) -> void:
        if needs:
            btn.text = "Download update (%.1f MB)" % [bytes / 1048576.0]
            btn.visible = true
    )
    dl.all_completed.connect(func(ok: bool) -> void:
        if ok: enter_game()
    )
    btn.pressed.connect(func() -> void:
        btn.visible = false
        dl.start()
    )

@onready var dl: DownloadProgress = $DownloadProgress
@onready var bar: ProgressBar = $ProgressBar
@onready var title: Label = $Title
@onready var status: Label = $Status

var _file: String = ""

func _ready() -> void:
    dl.file_started.connect(func(f: String) -> void: _file = f)
    dl.group_progress.connect(func(gname: String, idx: int, count: int, downloaded: int, total: int) -> void:
        title.text = "Downloading: %s (%d/%d)" % [gname, idx + 1, count]
        if total > 0:
            bar.value = float(downloaded) / total * 100.0
            status.text = "%s (%.2f / %.2f MB)" % [_file, downloaded / 1048576.0, total / 1048576.0]
    )
    dl.group_completed.connect(func(_n: String, _s: bool) -> void: bar.value = 0)
    dl.all_completed.connect(func(ok: bool) -> void:
        title.text = "Ready!" if ok else "Failed"
        bar.value = 100 if ok else 0
    )
    dl.start()

dl.group_progress.connect(func(gname: String, idx: int, count: int, downloaded: int, total: int) -> void:
    var group: DownloadGroup = dl.get_group(idx)
    var agg: Dictionary = group.get_aggregate_progress()
    status.text = "Files: %d/%d | %.2f MB" % [agg.done_count, agg.total_count, downloaded / 1048576.0]
)

DownloadProgress (base_folder = "user://content/")
├── DownloadGroup (group_name = "Base",  subfolder = "base",      source = "res://m/base.json")
├── DownloadGroup (group_name = "DLC 1", subfolder = "dlc/pack1", source = "https://cdn.com/dlc1.json")
└── DownloadGroup (group_name = "DLC 2", subfolder = "dlc/pack2", source = "https://cdn.com/dlc2.json")

# Player enters a zone that requires a new map
func _on_zone_entered(zone_id: String) -> void:
    var url: String = "https://cdn.example.com/maps/%s.bin" % zone_id
    var path: String = "user://maps/%s.bin" % zone_id
    var id: int = DLClient.download_file(url, path)

    DLClient.download_completed.connect(func(did: int, ok: bool) -> void:
        if did == id and ok:
            _load_zone(path)
    , CONNECT_ONE_SHOT)

func _on_buy_dlc(pack_name: String) -> void:
    var id: int = DLClient.download_json(
        "https://cdn.example.com/dlc/%s.json" % pack_name,
        "user://dlc/%s/" % pack_name
    )

    DLClient.download_progress.connect(func(did: int, dl: int, total: int) -> void:
        if did == id and total > 0:
            $DLCProgress.value = float(dl) / total * 100
    )

    DLClient.download_completed.connect(func(did: int, ok: bool) -> void:
        if did == id:
            $DLCProgress.visible = false
            if ok: _activate_dlc(pack_name)
    , CONNECT_ONE_SHOT)