Environment Variables

Complete reference of all environment variables supported by SkySend.

Server

Variable	Required	Default	Description
PORT	❌	3000	Server port (1-65535).
HOST	❌	0.0.0.0	Server bind address.
BASE_URL	✅	-	Public URL of the instance (used for CORS and generated links).
DATA_DIR	❌	./data	Directory for the database (DATA_DIR/db/skysend.db).
UPLOADS_DIR	❌	{DATA_DIR}/uploads	Directory for encrypted upload files. In Docker, defaults to /uploads.
TRUST_PROXY	❌	false	Trust X-Forwarded-For and X-Real-IP headers. Enable when behind a reverse proxy.
CORS_ORIGINS	❌	(empty)	Additional CORS origins, comma-separated.

Upload Limits

Variable	Required	Default	Description
MAX_FILE_SIZE	❌	2GB	Maximum upload size. Supports units: B, KB, MB, GB.
MAX_FILES_PER_UPLOAD	❌	32	Maximum number of files per multi-file upload.

Expiry Options

Variable	Required	Default	Description
EXPIRE_OPTIONS_SEC	❌	300,3600,86400,604800	Comma-separated list of selectable expiry times in seconds.
DEFAULT_EXPIRE_SEC	❌	86400	Default expiry time (must be one of EXPIRE_OPTIONS_SEC).

The default options translate to:

• 5 minutes (300)
• 1 hour (3600)
• 1 day (86400) - default
• 7 days (604800)

Download Limits

Variable	Required	Default	Description
DOWNLOAD_OPTIONS	❌	1,2,3,4,5,10,20,50,100	Comma-separated list of selectable download limits.
DEFAULT_DOWNLOAD	❌	1	Default download limit (must be one of DOWNLOAD_OPTIONS).

Cleanup

Variable	Required	Default	Description
CLEANUP_INTERVAL	❌	60	Interval for the automatic cleanup job in seconds.

Rate Limiting

Variable	Required	Default	Description
RATE_LIMIT_WINDOW	❌	60000	Rate limit window in milliseconds.
RATE_LIMIT_MAX	❌	60	Maximum requests per window per IP.

Upload Quota

Variable	Required	Default	Description
UPLOAD_QUOTA_BYTES	❌	0 (unlimited)	Maximum upload volume per user per window. 0 disables the quota. Supports units: B, KB, MB, GB.
UPLOAD_QUOTA_WINDOW	❌	86400	Quota time window in seconds (default: 24 hours).

Privacy-Preserving Quotas

Upload quotas use HMAC-SHA256 hashed IPs with a daily rotating key. No plaintext IP addresses are stored. The hash key rotates every 24 hours, making it impossible to correlate users across days.

Branding

Variable	Required	Default	Description
CUSTOM_TITLE	❌	SkySend	Displayed site title in the UI.
CUSTOM_COLOR	❌	(none)	Primary brand color as 6-digit hex code (e.g. 46c89d). The # prefix is optional.
CUSTOM_LOGO	❌	(none)	URL or absolute path to a custom logo (e.g. https://example.com/logo.svg or /custom-logo.svg).
CUSTOM_PRIVACY	❌	(none)	URL to your privacy policy page. Shown as a link in the footer if set.
CUSTOM_LEGAL	❌	(none)	URL to your legal notice / impressum page. Shown as a link in the footer if set.
CUSTOM_LINK_URL	❌	(none)	URL for a custom footer link. Must be used together with CUSTOM_LINK_NAME.
CUSTOM_LINK_NAME	❌	(none)	Display text for the custom footer link (max 50 characters).

Example

# docker-compose.yml
environment:
  CUSTOM_TITLE: MyShare
  CUSTOM_COLOR: ff6b35
  CUSTOM_LOGO: "https://example.com/my-logo.svg"
  CUSTOM_PRIVACY: "https://example.com/privacy"
  CUSTOM_LEGAL: "https://example.com/impressum"
  CUSTOM_LINK_URL: "https://example.com"
  CUSTOM_LINK_NAME: "My Website"

TIP

The # prefix is optional for CUSTOM_COLOR. Both ff6b35 and #ff6b35 are valid. Omitting the # avoids quoting issues in .env files.

Docker

Variable	Required	Default	Description
PUID	❌	1001	User ID the container runs as.
PGID	❌	1001	Group ID the container runs as.
SKIP_CHOWN	❌	false	Skip chown of /data and /uploads on startup. Required for NFS mounts or read-only filesystems where chown is not permitted. You must ensure correct permissions yourself.

Validation

SkySend validates all environment variables on startup using Zod:

• DEFAULT_EXPIRE_SEC must be one of the values in EXPIRE_OPTIONS_SEC
• DEFAULT_DOWNLOAD must be one of the values in DOWNLOAD_OPTIONS
• PORT must be between 1 and 65535
• MAX_FILE_SIZE must be a valid byte size string
• BASE_URL must be a valid URL (trailing slashes are stripped automatically)
• CUSTOM_COLOR must be a valid 6-digit hex color code (with or without # prefix)
• CUSTOM_LOGO must be a URL or an absolute path starting with /
• CUSTOM_PRIVACY must be a valid URL
• CUSTOM_LEGAL must be a valid URL
• CUSTOM_LINK_URL must be a valid URL
• CUSTOM_LINK_NAME must be at most 50 characters

If any variable is invalid, the server will fail to start with a descriptive error message.