Web Protocols
| Scheme | Purpose | Format | Example |
|---|---|---|---|
https |
Secure HTTP | https://host[:port]/path | https://example.com/page |
http |
Unencrypted HTTP | http://host[:port]/path | http://example.com/page |
wss |
Secure WebSocket | wss://host[:port]/path | wss://example.com/socket |
ws |
WebSocket | ws://host[:port]/path | ws://example.com/socket |
Communication
| Scheme | Purpose | Format |
|---|---|---|
mailto |
Email composition | mailto:address?subject=&body=&cc=&bcc= |
tel |
Phone call | tel:+1-555-123-4567 |
sms |
SMS message | sms:+15551234567?body=message |
mailto: Parameters
| Parameter | Purpose | Example |
|---|---|---|
subject |
Email subject line | ?subject=Hello%20World |
body |
Email body text | &body=Message%20here |
cc |
Carbon copy recipients | &cc=other@example.com |
bcc |
Blind carbon copy | &bcc=hidden@example.com |
// Simple email link mailto:support@example.com // With subject mailto:support@example.com?subject=Help%20Request // Full example mailto:support@example.com?subject=Bug%20Report&body=Description%3A%0A%0ASteps%3A&cc=team@example.com // Multiple recipients mailto:one@example.com,two@example.com // Tel: International format (recommended) tel:+1-555-123-4567 // SMS with body sms:+15551234567?body=Hi%20there
Location
| Scheme | Purpose | Format |
|---|---|---|
geo |
Geographic coordinates | geo:lat,lon[;u=uncertainty] |
maps |
Apple Maps | maps://?q=query or ?ll=lat,lon |
// Geographic coordinates (RFC 5870) geo:37.7749,-122.4194 // San Francisco geo:37.7749,-122.4194;u=100 // With 100m uncertainty geo:48.8584,2.2945 // Eiffel Tower // Apple Maps maps://?q=San+Francisco maps://?ll=37.7749,-122.4194 maps://?daddr=San+Francisco&saddr=Los+Angeles // Directions
Data & Files
| Scheme | Purpose | Format |
|---|---|---|
data |
Inline data | data:[mediatype][;base64],content |
file |
Local filesystem | file:///path/to/file |
blob |
JavaScript Blob object | blob:origin/uuid (browser-generated) |
Common Data URI MIME Types
| Type | MIME Type | Typical Use |
|---|---|---|
| Plain text | text/plain | Simple text content |
| HTML | text/html | Inline HTML documents |
| CSS | text/css | Inline stylesheets |
| JavaScript | application/javascript | Inline scripts |
| JSON | application/json | Inline data |
| SVG | image/svg+xml | Inline vector graphics |
| PNG | image/png | Inline raster images |
| JPEG | image/jpeg | Inline photos |
| GIF | image/gif | Inline animations |
| WebP | image/webp | Modern image format |
| application/pdf | Inline documents |
// Plain text (default)
data:,Hello%20World
// HTML
data:text/html,<h1>Hello</h1>
// Base64-encoded image
data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUA...
// SVG
data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg">...</svg>
// JSON
data:application/json,{"key":"value"}
// CSS
data:text/css,body{color:red}
App-Specific Schemes
| Scheme | Platform | Purpose |
|---|---|---|
slack:// |
Cross-platform | Open Slack channels/DMs |
spotify:// |
Cross-platform | Play tracks/albums |
zoommtg:// |
Cross-platform | Join Zoom meetings |
vscode:// |
Cross-platform | Open VS Code to file/folder |
itms-apps:// |
iOS | App Store links |
twitter:// |
Mobile | Open Twitter/X app |
fb:// |
Mobile | Open Facebook app |
instagram:// |
Mobile | Open Instagram app |
Developer Tools
| Scheme | Purpose | Example |
|---|---|---|
javascript |
Execute JavaScript | javascript:alert('hi') |
view-source |
View page source | view-source:https://example.com |
about |
Browser pages | about:blank, about:config |
chrome |
Chrome internal pages | chrome://settings |
devtools |
Chrome DevTools | devtools://devtools/... |
File Transfer
| Scheme | Purpose | Default Port | Status |
|---|---|---|---|
ftp |
File Transfer Protocol | 21 | Legacy |
ftps |
FTP over SSL/TLS | 990 | Rare |
sftp |
SSH File Transfer | 22 | Active |
ssh |
Secure Shell | 22 | Active |
URN Namespaces
URNs use the urn: scheme with various namespace identifiers:
| URN | Purpose | Example |
|---|---|---|
urn:isbn |
Book identifiers | urn:isbn:978-0-123-45678-9 |
urn:uuid |
Universally unique IDs | urn:uuid:f81d4fae-7dec-... |
urn:ietf:rfc |
IETF RFC documents | urn:ietf:rfc:3986 |
urn:oid |
Object Identifiers | urn:oid:2.16.840.1... |
urn:issn |
Serial publications | urn:issn:0317-8471 |
Scheme Registration
URI schemes are registered with IANA. Categories include:
| Category | Meaning | Examples |
|---|---|---|
| Permanent | Stable, well-defined schemes | http, https, mailto, tel |
| Provisional | Registered but not fully standardized | spotify, slack, zoommtg |
| Historical | No longer recommended | gopher, wais |
See IANA URI Schemes Registry for the complete list.