jwtninja 0.3.0

A simple and fully-typed auth library for Django Ninja based on PyJWT.

A session‑backed, fully‑typed authentication library for Django Ninja, powered by PyJWT.

❤️ Contributions Welcome! Feel free to submit a PR.

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Why JWT Ninja

• Stateful JWTs. Every token is tied to a DB-backed Session row — so you get token-based auth and revocation, device listing, and per-session state.
• Fully typed. Protected routes receive an AuthedRequest with request.auth.user and request.auth.session typed; OpenAPI schemas are generated with typed error responses.
• Batteries included. Five auth endpoints, a Django admin page, pluggable payload class for custom claims, pluggable authenticator for non-password login flows.

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Table of Contents

• Install
• Quick Start
• Protecting Your Views
• Endpoints
• Error Codes
• Configuration
• Custom Claims
• Custom Authenticator
• Session Management
• Development

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Install

JWT Ninja is a standard Django app. Install it with uv or pip:

uv add jwtninja
# or
pip install jwtninja

Requires Python 3.12+ and Django 5.x.

Quick Start

1. Add jwt_ninja to your INSTALLED_APPS:

# settings.py
INSTALLED_APPS = [
    ...,
    "jwt_ninja",
]

2. Run migrations to create the Session table:

python manage.py migrate

3. Mount the router on your Ninja API and wire up the error handler:

from ninja import NinjaAPI
from jwt_ninja import APIError
from jwt_ninja.api import router as auth_router
from jwt_ninja.handlers import error_handler

api = NinjaAPI()
api.add_router("auth/", auth_router)
api.add_exception_handler(APIError, error_handler)

That's it — you now have /auth/login/, /auth/refresh/, /auth/sessions/, /auth/logout/, and /auth/logout/all/.

Protecting Your Views

Decorate any Ninja route with auth=JWTAuth() and annotate the request as AuthedRequest for typed access to the authenticated user and session:

from ninja import Router
from jwt_ninja import AuthedRequest, JWTAuth

router = Router()


@router.get("/profile/", auth=JWTAuth())
def profile(request: AuthedRequest):
    user = request.auth.user        # the Django User
    session = request.auth.session  # the jwt_ninja Session
    return {"username": user.username, "session_id": session.id}

Per-session state

Each Session has a JSONField called data that you can use as scratch space for per-login state (feature flags, device info, onboarding step, etc.):

@router.post("/set-theme/", auth=JWTAuth())
def set_theme(request: AuthedRequest, theme: str):
    request.auth.session.data["theme"] = theme
    request.auth.session.save()
    return {"ok": True}

Endpoints

Method	Path	Purpose	Success	Errors
POST	/auth/login/	Issue a new access & refresh token pair	200	401
POST	/auth/refresh/	Refresh an access token	200	400, 401
GET	/auth/sessions/	List the caller's active sessions	200	401
POST	/auth/logout/	Expire the caller's current session	200	401
POST	/auth/logout/all/	Expire all of the caller's active sessions	200	401

POST /auth/login/

Request

{ "username": "alice", "password": "hunter2" }

Response (200)

{ "access_token": "eyJhbGci…", "refresh_token": "eyJhbGci…" }

POST /auth/refresh/

Request

{ "refresh_token": "eyJhbGci…" }

Response (200)

{ "access_token": "eyJhbGci…" }

Error Codes

All errors are returned as a JSON body {"error_code": "..."} with an appropriate HTTP status. Use these for i18n-friendly UX on the client.

Code	Status	Meaning
invalid_credentials	401	Username/password did not authenticate a user.
expired_token	401	Token's exp claim is in the past.
invalid_token	401	Token signature invalid, malformed, or wrong secret.
invalid_token_type	400	Sent an access token to /refresh/ or similar.
invalid_user	401	User attached to token no longer exists or is is_active=False.
session_not_found	401	Session referenced by the token has been deleted.
session_expired	401	Session was explicitly logged out or has an expired_at.

Configuration

All settings are Django settings prefixed with JWT_. Defaults shown below:

# settings.py
JWT_SECRET_KEY = SECRET_KEY                    # Defaults to Django's SECRET_KEY
JWT_ALGORITHM = "HS256"
JWT_ACCESS_TOKEN_EXPIRE_SECONDS = 300          # 5 minutes
JWT_REFRESH_TOKEN_EXPIRE_SECONDS = 365 * 3600  # 1 year
JWT_SESSION_EXPIRE_SECONDS = 365 * 3600        # 1 year
JWT_USER_LOGIN_AUTHENTICATOR = "jwt_ninja.authenticators.django_user_authenticator"
JWT_PAYLOAD_CLASS = "jwt_ninja.types.JWTPayload"

Setting	Type	Description
JWT_SECRET_KEY	str	Signing key. Defaults to Django's SECRET_KEY. See Signing key length.
JWT_ALGORITHM	str	PyJWT algorithm. Symmetric (HS*) or asymmetric (RS*, ES*, …).
JWT_ACCESS_TOKEN_EXPIRE_SECONDS	int	Lifetime of the short-lived access token.
JWT_REFRESH_TOKEN_EXPIRE_SECONDS	int	Lifetime of the refresh token.
JWT_SESSION_EXPIRE_SECONDS	int	Max age of the DB Session row before it's considered expired by housekeeping.
JWT_USER_LOGIN_AUTHENTICATOR	str	Dotted path to a callable (request, payload) -> User | None used by /auth/login/.
JWT_PAYLOAD_CLASS	str	Dotted path to a JWTPayload subclass if you need custom claims.

Signing key length

For HMAC algorithms (the HS* family, including the default HS256), RFC 7518 §3.2 requires the signing key to be at least the size of the hash output:

Algorithm	Minimum key size
HS256	32 bytes
HS384	48 bytes
HS512	64 bytes

Shorter keys are padded internally and give attackers a smaller space to search — an attacker who recovers the key can forge arbitrary tokens for any user.

JWT Ninja emits jwt_ninja.settings.InsecureJWTKeyWarning at startup if your configured key is too short, so you'll see it in your app logs as soon as the settings load. PyJWT also emits its own InsecureKeyLengthWarning at encode/decode time.

Django's get_random_secret_key() already produces 50-character keys, so fresh projects are fine. Short keys typically show up in older projects or in manually-set JWT_SECRET_KEY values. To generate a suitable key:

python -c "from django.core.management.utils import get_random_secret_key; print(get_random_secret_key())"

Rotating the key invalidates all existing JWT Ninja sessions (existing tokens fail signature verification), so users will need to re-authenticate after deploying the change.

Custom Claims

Need to embed extra data in the token itself (team id, feature flags, etc.)? Subclass JWTPayload and point JWT_PAYLOAD_CLASS at it — encode and decode sites both use the configured class, so your custom fields round-trip end-to-end.

# myapp/auth.py
from jwt_ninja import JWTPayload


class CustomJWTPayload(JWTPayload):
    team_id: int
    email: str

# settings.py
JWT_PAYLOAD_CLASS = "myapp.auth.CustomJWTPayload"

Note: If you add required fields, you'll also need a custom authenticator (below) or a custom login endpoint that knows how to populate them.

Overriding user_id

If your User model uses a non-integer primary key (UUIDField, CharField, etc.), override user_id on your payload subclass so the declared type matches what user.id actually is at runtime:

from uuid import UUID
from jwt_ninja import JWTPayload


class UUIDJWTPayload(JWTPayload):
    user_id: UUID  # or str, depending on your User PK


class StrPKJWTPayload(JWTPayload):
    user_id: str

Pydantic is strict about this: user_id=user.id at the login site passes the PK through without coercion, so the declared type and the runtime type must agree. The default JWTPayload declares user_id: int, which matches Django's default AutoField primary key.

Custom Authenticator

If you don't use Django's username/password flow (SSO, magic links, OTP, etc.), point JWT_USER_LOGIN_AUTHENTICATOR at a callable that returns a User or None:

# myapp/auth.py
from django.http import HttpRequest
from django.contrib.auth import get_user_model

User = get_user_model()


def magic_link_authenticator(request: HttpRequest, payload) -> User | None:
    try:
        return User.objects.get(magic_token=payload.token, magic_token_expired_at__gt=now())
    except User.DoesNotExist:
        return None

# settings.py
JWT_USER_LOGIN_AUTHENTICATOR = "myapp.auth.magic_link_authenticator"

The callable receives the raw HttpRequest and the parsed LoginSchema payload. Returning None produces a 401 invalid_credentials response.

Session Management

The Session model exposes a small set of helpers for common auth chores.

Invalidate all sessions (e.g., on password change)

from jwt_ninja.models import Session

# On password change, log the user out of every device
Session.invalidate_all_user_sessions(user)

This is a single bulk UPDATE that flips expired_at on every active session for the user.

Purge expired sessions (e.g., nightly cron)

Over time you'll accumulate rows for sessions that are long past their expired_at. Purge them with a scheduled task:

from jwt_ninja.models import Session

# django-crontab, Celery beat, management command, whatever you prefer
Session.purge_expired_sessions()

Inspect sessions in the admin

jwt_ninja registers a read-only SessionAdmin so ops can see who's logged in from where — just visit /admin/jwt_ninja/session/.

Development

# Clone and install
git clone https://github.com/dvf/jwt-ninja
cd jwt-ninja
uv sync

# Run tests
uv run pytest

# Lint + format
uv run ruff check .
uv run ruff format .

# Static type check
uv run pyrefly check

PRs are gated on all four checks. See .github/workflows/check-and-test.yml.

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License

MIT — see LICENSE.