Environment Variables Reference

Complete reference of all environment variables, their types, defaults, and validation rules.

Overview

All environment variables are validated on startup using Zod. Invalid values cause the server to fail with a descriptive error message. None of the variables are strictly required - all have sensible defaults for local development. For Docker deployments, DATA_DIR and UPLOADS_DIR are set automatically in the image.

Variables

PORT

Property	Value
Required	No
Type	Integer
Default	3000
Range	1 - 65535
Description	Server listening port

HOST

Property	Value
Required	No
Type	String
Default	0.0.0.0
Description	Server bind address

BASE_URL

Property	Value
Required	Yes
Type	URL
Default	-
Description	Public URL of the instance. Trailing slashes are stripped automatically.

DATA_DIR

Property	Value
Required	No
Type	String (path)
Default	./data
Description	Directory for the database. The SQLite DB is stored at DATA_DIR/db/skysend.db.

UPLOADS_DIR

Property	Value
Required	No
Type	String (path)
Default	DATA_DIR/uploads
Description	Directory for encrypted upload files. Falls back to DATA_DIR/uploads if not set. In Docker, defaults to /uploads for separate volume mounting.

MAX_FILE_SIZE

Property	Value
Required	No
Type	Byte size string
Default	2GB
Description	Maximum upload size. Supports: B, KB, MB, GB

MAX_FILES_PER_UPLOAD

Property	Value
Required	No
Type	Integer
Default	32
Range	>= 1
Required	No
Description	Maximum files per multi-file upload

EXPIRE_OPTIONS_SEC

Property	Value
Required	No
Type	Comma-separated integers
Default	300,3600,86400,604800
Description	Selectable expiry times in seconds

DEFAULT_EXPIRE_SEC

Property	Value
Required	No
Type	Integer
Default	86400
Validation	Must be one of EXPIRE_OPTIONS_SEC
Description	Default expiry time

DOWNLOAD_OPTIONS

Property	Value
Required	No
Type	Comma-separated integers
Default	1,2,3,4,5,10,20,50,100
Description	Selectable download limits

DEFAULT_DOWNLOAD

Property	Value
Required	No
Type	Integer
Default	1
Validation	Must be one of DOWNLOAD_OPTIONS
Description	Default download limit

CLEANUP_INTERVAL

Property	Value
Required	No
Type	Integer (seconds)
Default	60
Description	Interval for the automatic cleanup job

CUSTOM_TITLE

Property	Value
Required	No
Type	String
Default	SkySend
Description	Displayed site title

RATE_LIMIT_WINDOW

Property	Value
Required	No
Type	Integer (milliseconds)
Default	60000
Description	Rate limit sliding window size

RATE_LIMIT_MAX

Property	Value
Required	No
Type	Integer
Default	60
Description	Maximum requests per window per IP

UPLOAD_QUOTA_BYTES

Property	Value
Required	No
Type	Integer (bytes) or byte size string
Default	0 (disabled)
Description	Maximum upload volume per user per window. 0 disables quotas. Supports raw bytes or units: B, KB, MB, GB

UPLOAD_QUOTA_WINDOW

Property	Value
Required	No
Type	Integer (seconds)
Default	86400
Description	Quota time window

TRUST_PROXY

Property	Value
Required	No
Type	Boolean
Default	false
Description	Trust X-Forwarded-For / X-Real-IP headers from reverse proxy

CUSTOM_COLOR

Property	Value
Required	No
Type	Hex color code
Default	- (uses default theme)
Validation	Must match 6 hex digits, e.g. 46c89d (the # prefix is optional)
Description	Primary brand color for the web UI. Overrides the default primary color on buttons, links, icons, and other accented elements.

CUSTOM_LOGO

Property	Value
Required	No
Type	URL or absolute path
Default	- (uses built-in SkySend logo)
Validation	Must be a URL (https://...) or an absolute path (/...)
Description	URL or path to a custom logo image displayed in the web app header and as favicon. For local files, place them in the public/ directory (e.g. public/custom-logo.svg) and reference as /custom-logo.svg.

CUSTOM_PRIVACY

Property	Value
Required	No
Type	URL
Default	- (not shown in footer)
Validation	Must be a valid URL (https://...)
Description	URL to your privacy policy page. When set, a "Privacy Policy" link is displayed in the footer.

CUSTOM_LEGAL

Property	Value
Required	No
Type	URL
Default	- (not shown in footer)
Validation	Must be a valid URL (https://...)
Description	URL to your legal notice / impressum page. When set, a "Legal Notice" link is displayed in the footer.

CUSTOM_LINK_URL

Property	Value
Required	No
Type	URL
Default	- (not shown in footer)
Validation	Must be a valid URL (https://...)
Description	URL for a custom footer link. Must be used together with CUSTOM_LINK_NAME.

CUSTOM_LINK_NAME

Property	Value
Required	No
Type	String
Default	-
Validation	Max 50 characters
Description	Display text for the custom footer link defined by CUSTOM_LINK_URL. Both variables must be set for the link to appear.

PUID

Property	Value
Required	No
Type	Integer
Default	1001
Docker only	Yes
Description	User ID the container process runs as. Handled by the entrypoint script.

PGID

Property	Value
Required	No
Type	Integer
Default	1001
Docker only	Yes
Description	Group ID the container process runs as. Handled by the entrypoint script.

Validation Rules

• DEFAULT_EXPIRE_SEC must be included in EXPIRE_OPTIONS_SEC
• DEFAULT_DOWNLOAD must be included in DOWNLOAD_OPTIONS
• PORT must be between 1 and 65535
• MAX_FILE_SIZE must be a valid byte size string with a recognized unit
• BASE_URL must be a valid URL
• CUSTOM_COLOR must be a 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