Auth

JWT Fields Reference

Complete reference for JWT fields in Supabase

This page provides a comprehensive reference for all JWT fields 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:

FieldTypeDescriptionExample
issstringIssuer - The entity that issued the JWT"https://project-ref.supabase.co/auth/v1"
audstring | string[]Audience - The intended recipient of the JWT"authenticated" or "anon"
expnumberExpiration Time - Unix timestamp when the token expires1640995200
iatnumberIssued At - Unix timestamp when the token was issued1640991600
substringSubject - The user ID (UUID)"123e4567-e89b-12d3-a456-426614174000"
rolestringRole - User's role in the system"authenticated", "anon", "service_role"
aalstringAuthenticator Assurance Level - Authentication strength"aal1", "aal2"
session_idstringSession ID - Unique session identifier"session-uuid"
emailstringEmail - User's email address"user@example.com"
phonestringPhone - User's phone number"+1234567890"
is_anonymousbooleanAnonymous Flag - Whether the user is anonymousfalse

Optional claims

These claims may be present depending on the authentication context:

FieldTypeDescriptionExample
jtistringJWT ID - Unique identifier for the JWT"jwt-uuid"
nbfnumberNot Before - Unix timestamp before which the token is invalid1640991600
app_metadataobjectApp Metadata - Application-specific user data{"provider": "email"}
user_metadataobjectUser Metadata - User-specific data{"name": "John Doe"}
amrarrayAuthentication Methods Reference - List of authentication methods used[{"method": "password", "timestamp": 1640991600}]

Special fields

FieldTypeDescriptionExampleContext
refstringProject Reference - Supabase project identifier"abcdefghijklmnopqrst"Anon/Service role tokens only

Field value constraints

Authenticator assurance level (aal)

ValueDescription
"aal1"Single-factor authentication (password, OAuth, etc.)
"aal2"Multi-factor authentication (password + TOTP, etc.)

Role values (role)

ValueDescriptionUse Case
"anon"Anonymous userPublic access with RLS policies
"authenticated"Authenticated userStandard user access
"service_role"Service roleAdmin privileges (server-side only)

Audience values (aud)

ValueDescription
"authenticated"For authenticated user tokens
"anon"For anonymous user tokens

Authentication methods (amr.method)

ValueDescription
"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
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
{  "aal": "aal1",  "amr": [    {      "method": "password",      "timestamp": 1640991600    }  ],  "app_metadata": {    "provider": "email",    "providers": ["email"]  },  "aud": "authenticated",  "email": "user@example.com",  "exp": 1640995200,  "iat": 1640991600,  "iss": "https://abcdefghijklmnopqrst.supabase.co/auth/v1",  "phone": "",  "role": "authenticated",  "session_id": "123e4567-e89b-12d3-a456-426614174000",  "sub": "123e4567-e89b-12d3-a456-426614174000",  "user_metadata": {    "name": "John Doe"  },  "is_anonymous": false}

Anonymous user token

1
2
3
4
5
6
7
{  "iss": "supabase",  "ref": "abcdefghijklmnopqrst",  "role": "anon",  "iat": 1640991600,  "exp": 1640995200}

Service role token

1
2
3
4
5
6
7
{  "iss": "supabase",  "ref": "abcdefghijklmnopqrst",  "role": "service_role",  "iat": 1640991600,  "exp": 1640995200}

Language-Specific considerations

Rust

In Rust, the ref field is a reserved keyword. When deserializing JWTs, you'll need to handle this:

1
2
3
4
5
6
7
8
9
10
11
12
use serde::{Deserialize, Serialize};#[derive(Debug, Deserialize, Serialize)]struct JwtClaims {    iss: String,    #[serde(rename = "ref")] // Handle reserved keyword    project_ref: Option<String>,    role: String,    iat: i64,    exp: i64,    // ... other fields}

TypeScript/JavaScript

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
interface  {  : string  : string | string[]  : number  : number  : string  : string  : 'aal1' | 'aal2'  : string  : string  : string  : boolean  ?: string  ?: number  ?: <string, any>  ?: <string, any>  ?: <{    : string    : number  }>  ?: string // Only in anon/service role tokens}

Python

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
from typing import Optional, Union, List, Dict, Anyfrom dataclasses import dataclass@dataclassclass AmrEntry:    method: str    timestamp: int@dataclassclass JwtClaims:    iss: str    aud: Union[str, List[str]]    exp: int    iat: int    sub: str    role: str    aal: str    session_id: str    email: str    phone: str    is_anonymous: bool    jti: Optional[str] = None    nbf: Optional[int] = None    app_metadata: Optional[Dict[str, Any]] = None    user_metadata: Optional[Dict[str, Any]] = None    amr: Optional[List[AmrEntry]] = None    ref: Optional[str] = None  # Only in anon/service role tokens

Go

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
type AmrEntry struct {    Method    string `json:"method"`    Timestamp int64  `json:"timestamp"`}type JwtClaims struct {    Iss         string                 `json:"iss"`    Aud         interface{}            `json:"aud"` // string or []string    Exp         int64                  `json:"exp"`    Iat         int64                  `json:"iat"`    Sub         string                 `json:"sub"`    Role        string                 `json:"role"`    Aal         string                 `json:"aal"`    SessionID   string                 `json:"session_id"`    Email       string                 `json:"email"`    Phone       string                 `json:"phone"`    IsAnonymous bool                   `json:"is_anonymous"`    Jti         *string                `json:"jti,omitempty"`    Nbf         *int64                 `json:"nbf,omitempty"`    AppMetadata map[string]interface{} `json:"app_metadata,omitempty"`    UserMetadata map[string]interface{} `json:"user_metadata,omitempty"`    Amr         []AmrEntry             `json:"amr,omitempty"`    Ref         *string                `json:"ref,omitempty"` // Only in anon/service role tokens}

Validation guidelines

When implementing JWT validation on your server:

  1. Check Required Fields: Ensure all required claims are present
  2. Validate Types: Verify field types match expected types
  3. Check Expiration: Validate exp timestamp is in the future
  4. Verify Issuer: Ensure iss matches your Supabase project
  5. Check Audience: Validate aud matches expected audience
  6. 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