Jmaple

A pluggable JMAP server framework, built on FastAPI.

📖 Documentation — tutorial, topic guides, and API reference.

JMAP (RFC 8620) was designed as a generic JSON-over-HTTP sync protocol with a clean separation between core machinery (sessions, request/response envelope, method dispatch, references, state strings, push) and data-type capabilities (Mail = RFC 8621, Contacts = RFC 9610, …). Jmaple takes that separation seriously and treats every data type — including Mail — as a plugin.

• Python: 3.14+
• Package manager: uv
• Web framework: FastAPI
• ORM: SQLAlchemy (async)
• Migrations: Alembic (dynamically discovers plugin migrations via Python entry points)
• Operator interface: a single jmaple CLI — there is no separate admin web UI.

What's in the box

• Full JMAP Core (RFC 8620): session resource, method dispatch, result references, state strings, error handling, upload/download.
• A clean plugin contract so a third party can add a new capability (urn:vendor:thing) by registering schemas and method handlers, without touching the core.
• A pluggable auth subsystem (JWT, OIDC, opaque bearer) wired into a unified accounts/grants authorization layer stored in the database.
• A pluggable persistence layer built on async SQLAlchemy 2.0 + Alembic, with PostgreSQL as the default and SQLite for development.
• All three JMAP push transports: SSE (/eventsource), WebSocket (RFC 8887), and PushSubscription webhooks (RFC 8620 §7.2).
• A reference plugin (urn:jmaple:notes) demonstrating end-to-end use of every abstraction.

Quickstart

You need uv and just on your $PATH.

just install              # uv sync
cp .env.example .env      # tweak JMAPLE_DATABASE_URL, JMAPLE_SECRET_KEY, …
just migrate              # apply Alembic migrations
just serve                # uvicorn at http://localhost:8000

# In another terminal: issue the first admin token.
uv run jmaple token issue --user alice --admin

Then point a JMAP client at http://localhost:8000/.well-known/jmap with the issued token in the Authorization: Bearer <token> header.

Top-level recipes

The jmaple CLI

The CLI is the only operator interface. Run uv run jmaple --help for the full tree. Top-level groups:

• jmaple serve — start the FastAPI server.
• jmaple migrate {upgrade, downgrade, revision, history, current} — Alembic.
• jmaple user {list, show, create, promote} — manage users.
• jmaple account {list, create, rename, delete} — manage accounts.
• jmaple grant {list, add, remove} — manage account-sharing grants.
• jmaple token {issue, list, revoke} — manage opaque bearer tokens.
• jmaple subscription {list, revoke} — inspect / revoke push subscriptions.
• jmaple capability {list, settings get, settings set} — inspect / configure registered capabilities.
• jmaple version — print the installed version.

Public API

When writing a capability, import from these modules. Everything under jmaple.core.*, jmaple.auth.*, and jmaple.api.* is internal and may change without notice.

A minimal capability looks like:

# my_plugin/models.py
from jmaple.db import Base, JMAPObject
from sqlalchemy import String
from sqlalchemy.orm import Mapped, mapped_column

class Todo(Base, JMAPObject):
    __tablename__ = "todos"
    text: Mapped[str] = mapped_column(String(512))

# my_plugin/capability.py
from jmaple.capabilities import CrudCapability
from my_plugin.models import Todo
from my_plugin.schema import TodoSchema, TodoCreate

class TodosCapability(CrudCapability):
    urn = "urn:example:todos"
    data_type_name = "Todo"
    model = Todo
    schema_class = TodoSchema
    create_schema_class = TodoCreate

capability = TodosCapability.as_capability()

Register it programmatically in your ASGI app module:

# my_plugin/app.py
from jmaple.app import create_app
from jmaple.capabilities import register_capability
from my_plugin import models as _models  # noqa: F401  # land Todo on Base.metadata
from my_plugin.capability import capability

register_capability(capability)
app = create_app()

Run with uvicorn my_plugin.app:app. For CLI ops, write a parallel my_plugin/cli.py that registers the capability then re-exposes jmaple.cli:app, and point pyproject.toml's jmaple script at it.

Environment

The server reads its config from .env in the working directory (via pydantic-settings). Copy .env.example and adjust as needed:

• JMAPLE_DATABASE_URL — SQLAlchemy async URL (defaults to a local SQLite file).
• JMAPLE_SECRET_KEY — random string for state-vector / session signing.
• JMAPLE_DEBUG — true for verbose logs.

Operators of the published PyPI wheel set the same JMAPLE_* env at deploy time.