FastAPI quickstart

FastAPI + React. Requires Python ≥ 3.10, FastAPI ≥ 0.115 (Starlette ≥ 0.40) and a SQLAlchemy 2 Engine for OpenReceive’s two tables.

1. Install

pip install "openreceive[fastapi]"
npm install @openreceive/react

OpenReceive is one Python distribution with framework extras. openreceive[fastapi] brings FastAPI, Starlette and SQLAlchemy. The base package includes the wallet client (websockets, coincurve, cryptography), the HTTP engine and the openreceive CLI. The npm package is the checkout UI for your frontend. On a different stack, swap the two: use openreceive[django] with the Django quickstart. A page without a bundler uses @openreceive/elements instead of React.

	Packages
Server	`openreceive[fastapi]`, `openreceive[django]`, `openreceive[sqlalchemy]` (Flask and plain WSGI/ASGI: the Flask recipe)
Frontend	`@openreceive/react`, `@openreceive/vue`, `@openreceive/svelte`, `@openreceive/angular`, `@openreceive/elements` (plain HTML)

Use uv or a virtualenv on Python 3.10 or newer. A system Python 3.9 cannot install the package.

2. Migrate the payment tables

openreceive scaffold payments --alembic --dialect postgres    # or sqlite | mysql

openreceive scaffold payments --alembic writes one Alembic revision into alembic/versions/. The DDL is frozen in the file, and it creates two tables:

openreceive_payments, the payment attempts
openreceive_meta, the reconcile gate

Set the revision’s down_revision to your current head (alembic heads). Then apply it the way you apply your own revisions: alembic upgrade head. The command never opens a database connection. → openreceive scaffold payments

No Alembic? openreceive scaffold payments --sql --dialect postgres prints the same DDL. Feed it to psql, a Flyway file, or whatever runs your migrations. In code, payments_schema_sql(dialect) from openreceive.storage.sql returns the same string. OpenReceive owns the tables’ logic at runtime: locking, write-once settlement, and the reconciliation state machine. There is nothing else to generate. Details: Payment storage.

3. Add wallet credentials

Put the credentials in the server’s environment. That can be a .env your process manager loads, uvicorn --env-file .env, or your secret store:

NWC_URI=
LSC_URI_PRIMARY=
LSC_URI_BACKUP=

Get a receive-only NWC code from a compatible wallet (get one here). Put it in NWC_URI.
Optional: set up a swap provider. Put its connection string in LSC_URI_PRIMARY, and a second one in LSC_URI_BACKUP if you have one.

Never put these values in browser code. Your app refuses to start if the NWC code also advertises spend methods such as pay_invoice. Create a receive-only code instead (Security).

OpenReceive reads os.environ, so a .env file on disk is not enough on its own. uvicorn --env-file .env loads one in development. In production, the process manager or secret store injects the values. Environment variables lists every variable.

4. Wire OpenReceive

The wiring takes twelve lines:

your three hooks as a Host
a router included under a prefix
a lifespan that checks the wallet at startup

The router builds the wallet client from NWC_URI and mounts the framework-free engine. There is no background reconciler, meaning no job that checks pending payments on a timer. Settlement runs during normal requests instead, through the durable reconcile gate.

from fastapi import FastAPI
from sqlalchemy import create_engine
from openreceive.fastapi import openreceive_lifespan, openreceive_router
from openreceive.server import Host
from .app import current_user, orders  # your existing models and auth dependency

# OpenReceive's own sync Engine for its two tables — the SAME database as
# your orders, its own connection pool. On SQLite give it a dedicated Engine.
engine = create_engine("postgresql+psycopg://…")

host = Host(
    # The price for a reference — here, your order id — from your own data;
    # OpenReceive converts it into the Lightning invoice. Return None when
    # there is nothing to pay for. `value` is a decimal STRING from the order
    # row, never a float and never a request param. `description` is what the
    # payer is buying, in your own words.
    amount_for=lambda reference: (
        {"currency": "USD", "value": str(order.total), "description": order.summary}
        if (order := orders.find(reference))
        else None
    ),
    # Your own access check: may this caller do this action to this reference?
    # `context.request` is the untouched Starlette Request — reuse the same
    # dependency your order page uses. `context.resource["reference"]` is a
    # claim the payer's browser sent, not proof.
    authorize=lambda context: orders.viewer_may(
        current_user(context.request), context.resource["reference"], context.action
    ),
    # INSIDE the settlement transaction; runs only for the reference's first
    # settled attempt. Use `settlement.connection` (that transaction) for the
    # order write, never a second session. The WHERE clause is the lock.
    on_paid=lambda settlement: settlement.connection.execute(
        orders.claim_paid(settlement.reference, settlement.paid_at)
    ),
)

app = FastAPI(lifespan=openreceive_lifespan(host, engine=engine))
app.include_router(
    # Recommended for public web shops: `rate_limiting=True` caps invoice
    # creation at 60 per client IP per hour. Leave it off (the default) for
    # point-of-sale deployments, where many payers share the terminal's IP.
    openreceive_router(host, engine=engine, rate_limiting=True),
    prefix="/openreceive",
)

authorize receives the Starlette Request. Cookies, headers, and whatever SessionMiddleware or auth dependency this app already has are readable there. FastAPI ships no session of its own, so you must bind the payer’s reference to something the request proves. Behind a reverse proxy, run uvicorn with --proxy-headers. Otherwise rate_limiting counts the proxy as the one payer.

There is no CSRF layer to add. FastAPI has no CSRF (cross-site request forgery) layer, and OpenReceive does not want one. Every mounted route refuses a request whose Sec-Fetch-Site header says cross-site. That stops another origin’s page from minting or refunding on a logged-in payer’s behalf. The Express and Fastify adapters rely on exactly the same protection. Its limit is the header itself. A client that does not send it, such as a non-browser or an old browser, is not refused. So authorize stays the actual boundary. Security has the full account.

openreceive_lifespan runs the receive-only wallet preflight when uvicorn starts. It stops the process if the code is missing, unreachable, or able to spend. That way the deploy fails instead of the first payer. Pass lazy=True for tests and for build steps that have no secrets. The first request then checks the wallet, and requests get 503 WALLET_UNAVAILABLE until the check passes. → openreceive_router · openreceive_lifespan · the authorize context

rate_limiting=True is for public web shops. Leave it off for point-of-sale, where many payers share one IP. → Rate limiting

An optional worker, openreceive notifications --app main:app, listens for wallet payment notifications so settlement does not wait for the next page load. → openreceive notifications

Your app also needs an ordinary order-creation route that validates the cart, prices with exact decimal math, and returns the order id the page will pass as the reference. OpenReceive never prices from payer input.

The reference is a string you choose, and it is the fulfillment identity: your order id. Use one per thing you fulfill, create it before checkout, keep it across retries, and never reuse it. OpenReceive never looks inside it, but the reference still matters:

on_paid commits fulfillment once per reference.
A new checkout under a reference that already settled is refused with 409.
A fresh id per page load lets one order be paid twice.

Naming boundary: the Python API is snake_case (payment_hash, amount_msats), and so is everything on the wire. The mounted HTTP routes and the browser snapshots use the same names.

5. Render checkout

import { Checkout } from "@openreceive/react";
import "@openreceive/react/styles.css";

<Checkout reference={order.id} prefix="/openreceive" />;

The checkout renders, polls, and settles itself.

@openreceive/react and @openreceive/elements each ship a compiled styles.css. Each sheet is self-contained, so a plain <link rel="stylesheet"> works with no build step. Each is also scoped: every rule applies only inside what OpenReceive renders.

Serve the compiled styles.css without Tailwind processing. Import it from JavaScript if your bundler handles CSS, or use a plain <link rel="stylesheet">. Do not @import it into your app’s Tailwind entry. Its rules have zero specificity, so your page’s styles can override checkout styles. Scoping does not prevent that.

<Checkout> is complete as rendered. It already shows the description from amountFor and the collapsed transaction-details panel. Do not build a custom UI to show them. The display rules for them become your job only if you replace the drop-in component (Checkout UX).

Match the host page’s theme. By default the checkout follows the payer’s stored choice, then the system color scheme. If this page always uses one theme, lock it with <Checkout theme="dark" … />. On the custom element, set the theme attribute. Locking the theme keeps a white card off a dark page. CSS variables under data-theme style the checkout. Frontend checkout lists the settings you can change.

Everything the checkout draws ships inside the JavaScript: the payment-method icons, the wallet logos, and the pay tutorials. There is no image file to copy or serve, and no asset option to set. Deploy your normal JavaScript and CSS build output, including any generated JavaScript chunks. Bundlers with code splitting can wait to load tutorial screenshots until a tutorial first opens. Single-file builds, including the standalone checkout, include them from the start. If your Content-Security-Policy has a strict img-src, allow data: (Provider registry).

That is the whole loop. Your server owns the price and the order. The payer gets an invoice. onPaid runs inside the settlement transaction. If that transaction rolls back, the callback may run again. For delivery to outside systems, use an outbox in your app: record the message in the transaction and send it after commit.

A page without a bundler renders the same checkout as a custom element: <openreceive-checkout reference="…" prefix="/openreceive"> from @openreceive/elements. You can also serve its standalone build from your static directory.

Buy a Button is a runnable illustration of the boundary (examples/buttons/server/fastapi). It is not a template to copy models from. It keeps products, visitors and orders in SQLite, and the three hooks are the only bridge to OpenReceive. It is the smallest correct FastAPI integration of the packaged checkout. Map that shape onto the models in THIS app.

6. Verify

openreceive doctor --app main:app

openreceive doctor checks Python, NWC_URI, and swap-provider configuration. It also probes the wallet relay to confirm the code is receive-only. With --app module:attr (your FastAPI app, the router, or an OpenReceiveApp), it also confirms the migration ran and names any hook still on a placeholder. Add --url http://localhost:8000 to confirm the routes are mounted. Every failing line states its own fix, and the command exits with code 1 when anything fails. openreceive debug-report prints the same output as a redacted support report. → openreceive doctor

Then open the checkout in a browser, confirm the payment-method icons and wallet logos render, and open a wallet’s pay tutorial to check its screenshots. If an image is missing, inspect the console for CSP violations and the Network panel for failed JavaScript chunks. Allow data: in img-src and deploy the complete build output. Do not add image routes, copy package source images, or use registry icon_path / tutorial path keys as browser URLs.

Swap credentials (LSC_URI_*) stay server-side too. The provider order id and token live in the attempt’s server-only swap_data column. They never reach a response or a log (Automated swaps).

Authorization — your policy boundary
Payment storage — the table the library owns, and its state machine
Frontend Checkout — what the browser side is responsible for
Automated Swaps — swap_data, and what turning swaps on commits you to
Swap refunds — the refund flow, and the per-order URL a payer needs to come back and claim a refund. Read it before you set LSC_URI_PRIMARY
Security — which secrets must stay on the server

More on wiring, storage, and routes: Authorization, Payment storage, API reference.