JWT Claims Reference
Complete reference for claims appearing in JWTs created by Supabase Auth
This page provides a comprehensive reference for all JWT claims used in Supabase authentication tokens. This information is essential for server-side JWT validation and serialization, especially when implementing authentication in languages like Rust where field names like ref are reserved keywords.
JWT structure overview
Supabase JWTs follow the standard JWT structure with three parts:
- Header: Contains algorithm and key information
- Payload: Contains the claims (user data and metadata)
- Signature: Cryptographic signature for verification
The payload contains various claims that provide user identity, authentication level, and authorization information.
Required claims
These claims are always present in Supabase JWTs and cannot be removed:
| Field | Type | Description | Example |
|---|---|---|---|
iss | string | Issuer - The entity that issued the JWT | "https://project-ref.supabase.co/auth/v1" |
aud | string | string[] | Audience - The intended recipient of the JWT | "authenticated" or "anon" |
exp | number | Expiration Time - Unix timestamp when the token expires | 1640995200 |
iat | number | Issued At - Unix timestamp when the token was issued | 1640991600 |
sub | string | Subject - The user ID (UUID) | "123e4567-e89b-12d3-a456-426614174000" |
role | string | Role - User's role in the system | "authenticated", "anon", "service_role" |
aal | string | Authenticator Assurance Level - Authentication strength | "aal1", "aal2" |
session_id | string | Session ID - Unique session identifier | "session-uuid" |
email | string | Email - User's email address | "user@example.com" |
phone | string | Phone - User's phone number | "+1234567890" |
is_anonymous | boolean | Anonymous Flag - Whether the user is anonymous | false |
Optional claims
These claims may be present depending on the authentication context:
| Field | Type | Description | Example |
|---|---|---|---|
jti | string | JWT ID - Unique identifier for the JWT | "jwt-uuid" |
nbf | number | Not Before - Unix timestamp before which the token is invalid | 1640991600 |
app_metadata | object | App Metadata - Application-specific user data | {"provider": "email"} |
user_metadata | object | User Metadata - User-specific data | {"name": "John Doe"} |
amr | array | Authentication Methods Reference - List of authentication methods used | [{"method": "password", "timestamp": 1640991600}] |
Special claims
| Field | Type | Description | Example | Context |
|---|---|---|---|---|
ref | string | Project Reference - Supabase project identifier | "abcdefghijklmnopqrst" | Anon/Service role tokens only |
Field value constraints
Authenticator assurance level (aal)
| Value | Description |
|---|---|
"aal1" | Single-factor authentication (password, OAuth, etc.) |
"aal2" | Multi-factor authentication (password + TOTP, etc.) |
Role values (role)
| Value | Description | Use Case |
|---|---|---|
"anon" | Anonymous user | Public access with RLS policies |
"authenticated" | Authenticated user | Standard user access |
"service_role" | Service role | Admin privileges (server-side only) |
Audience values (aud)
| Value | Description |
|---|---|
"authenticated" | For authenticated user tokens |
"anon" | For anonymous user tokens |
Authentication methods (amr.method)
| Value | Description |
|---|---|
"oauth" | OAuth provider authentication |
"password" | Email/password authentication |
"otp" | One-time password |
"totp" | Time-based one-time password |
"recovery" | Account recovery |
"invite" | Invitation-based signup |
"sso/saml" | SAML single sign-on |
"magiclink" | Magic link authentication |
"email/signup" | Email signup |
"email_change" | Email change |
"token_refresh" | Token refresh |
"anonymous" | Anonymous authentication |
JWT examples
Authenticated user token
1{2 "aal": "aal1",3 "amr": [4 {5 "method": "password",6 "timestamp": 16409916007 }8 ],9 "app_metadata": {10 "provider": "email",11 "providers": ["email"]12 },13 "aud": "authenticated",14 "email": "user@example.com",15 "exp": 1640995200,16 "iat": 1640991600,17 "iss": "https://abcdefghijklmnopqrst.supabase.co/auth/v1",18 "phone": "",19 "role": "authenticated",20 "session_id": "123e4567-e89b-12d3-a456-426614174000",21 "sub": "123e4567-e89b-12d3-a456-426614174000",22 "user_metadata": {23 "name": "John Doe"24 },25 "is_anonymous": false26}Anonymous user token
1{2 "iss": "supabase",3 "ref": "abcdefghijklmnopqrst",4 "role": "anon",5 "iat": 1640991600,6 "exp": 16409952007}Service role token
1{2 "iss": "supabase",3 "ref": "abcdefghijklmnopqrst",4 "role": "service_role",5 "iat": 1640991600,6 "exp": 16409952007}Language-Specific considerations
Rust
In Rust, the ref field is a reserved keyword. When deserializing JWTs, you'll need to handle this:
1use serde::{Deserialize, Serialize};23#[derive(Debug, Deserialize, Serialize)]4struct JwtClaims {5 iss: String,6 #[serde(rename = "ref")] // Handle reserved keyword7 project_ref: Option<String>,8 role: String,9 iat: i64,10 exp: i64,11 // ... other claims12}TypeScript/JavaScript
1interface {2 : string3 : string | string[]4 : number5 : number6 : string7 : string8 : 'aal1' | 'aal2'9 : string10 : string11 : string12 : boolean13 ?: string14 ?: number15 ?: <string, any>16 ?: <string, any>17 ?: <{18 : string19 : number20 }>21 ?: string // Only in anon/service role tokens22}Python
1from typing import Optional, Union, List, Dict, Any2from dataclasses import dataclass34@dataclass5class AmrEntry:6 method: str7 timestamp: int89@dataclass10class JwtClaims:11 iss: str12 aud: Union[str, List[str]]13 exp: int14 iat: int15 sub: str16 role: str17 aal: str18 session_id: str19 email: str20 phone: str21 is_anonymous: bool22 jti: Optional[str] = None23 nbf: Optional[int] = None24 app_metadata: Optional[Dict[str, Any]] = None25 user_metadata: Optional[Dict[str, Any]] = None26 amr: Optional[List[AmrEntry]] = None27 ref: Optional[str] = None # Only in anon/service role tokensGo
1type AmrEntry struct {2 Method string `json:"method"`3 Timestamp int64 `json:"timestamp"`4}56type JwtClaims struct {7 Iss string `json:"iss"`8 Aud interface{} `json:"aud"` // string or []string9 Exp int64 `json:"exp"`10 Iat int64 `json:"iat"`11 Sub string `json:"sub"`12 Role string `json:"role"`13 Aal string `json:"aal"`14 SessionID string `json:"session_id"`15 Email string `json:"email"`16 Phone string `json:"phone"`17 IsAnonymous bool `json:"is_anonymous"`18 Jti *string `json:"jti,omitempty"`19 Nbf *int64 `json:"nbf,omitempty"`20 AppMetadata map[string]interface{} `json:"app_metadata,omitempty"`21 UserMetadata map[string]interface{} `json:"user_metadata,omitempty"`22 Amr []AmrEntry `json:"amr,omitempty"`23 Ref *string `json:"ref,omitempty"` // Only in anon/service role tokens24}Validation guidelines
When implementing JWT validation on your server:
- Check Required Fields: Ensure all required claims are present
- Validate Types: Verify field types match expected types
- Check Expiration: Validate
exptimestamp is in the future - Verify Issuer: Ensure
issmatches your Supabase project - Check Audience: Validate
audmatches expected audience - Handle Reserved Keywords: Use field renaming for languages like Rust
Security considerations
- Always validate the JWT signature before trusting any claims
- Never expose service role tokens to client-side code
- Validate all claims before trusting the JWT
- Check token expiration on every request
- Use HTTPS for all JWT transmission
- Rotate JWT secrets regularly
- Implement proper error handling for invalid tokens