UseThatApp Documentation

Sell your web app from your own website — UseThatApp is the merchant of record. Put live prices and Buy buttons on your site; UseThatApp runs the hosted checkout, processes payment, calculates and remits tax, and handles refunds and chargebacks. The buyer lands back in your app with their purchase live — the license is created during checkout, no webhooks — and you get payouts via Stripe. Your app verifies each purchase with a license key — or lets UseThatApp run sign-in — through one SDK: usethatapp on PyPI and npm.

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Every page on this site is fully pre-rendered static HTML — no JavaScript needed. For the fastest path, fetch docs.usethatapp.com/llms.txt (an index of all pages with summaries and integration rules) or docs.usethatapp.com/llms-full.txt (the entire site as one Markdown file — no crawling required). Page URLs are extensionless routes; the same list is in sitemap.xml.

One Merchant of Record, Two Ways to Verify

Merchant of record

The service everything else hangs off. Hosted buy links and a live pricing API; we take the payment, remit the tax, handle refunds and chargebacks, and pay you via Stripe.

License keys

Verify purchases while keeping your own auth. Every purchase mints a key your server validates in one call — included in the per-sale fee, no login of ours involved.

Hosted sign-in

Or let us run login: buyers return from checkout already signed in, and the same session answers what they bought. An optional add-on, free for an introductory period.

The Loop

Everything in these docs serves one journey — a visitor on your website becoming a paying user of your app:

Live prices on your site. Your pricing page renders from the Pricing API (get_prices / getPrices, or plain fetch — it's public and CORS-enabled). Never hardcode a price.
Buy button → hosted checkout. Each price carries a ready-made buy_url (or build one with purchase_url / purchaseUrl). UseThatApp runs checkout as the merchant of record.
Back into your app. The license is created synchronously during checkout, so what they bought is live the moment they land — no webhooks, no polling.
Verify, whichever way suits your app. Keeping your own accounts? The return carries a uta_order ref you exchange for a license key, then validate_license_key / validateLicenseKey is your gate. Rather we ran login? Sign in with UseThatApp returns them signed in and get_entitlement answers from that session. Either way, branch on the stable product_public_id.
Manage and upgrade. Deep-link "Manage subscription" with manage_url / manageUrl; upsell with another purchase link.

Your app's marketplace listing on usethatapp.com is a complementary discovery channel — in external listing mode its card links straight out to your own site. Purchases are open to buyers in the US, the EU, Canada, Australia and more; sellers must be based in the United States.

Quick Example

Live prices on your page, then gate what the buyer bought — shown here in Hosted sign-in mode (keys mode swaps the gate for validate_license_key, see License Keys). The usethatapp SDK (PyPI / npm) is a confidential, server-side client — it holds your client secret and never runs in the browser:

Python

app.py
from usethatapp import get_entitlement, get_prices, purchase_url

# Your pricing page — live prices, never hardcoded:
prices = get_prices()          # AppPrices(..., prices=(Price(...), ...))
for p in prices.prices:
    show_plan(p.product_name, p.amount, p.currency, p.buy_url)

# Your gate, Hosted sign-in mode (keys mode: validate_license_key):
ent = get_entitlement(session["uta_access_token"])
if ent.entitled and ent.product_public_id == "prod_<your-pro-id>":
    ...  # serve paid content
else:
    offer_upgrade(purchase_url("<prc-price-id>"))

JavaScript

server.mjs
import { getEntitlement, getPrices, purchaseUrl } from "usethatapp";

// Your pricing page — live prices, never hardcoded:
const { prices } = await getPrices();
prices.forEach((p) =>
  showPlan(p.product_name, p.amount, p.currency, p.buy_url));

// Your gate, Hosted sign-in mode (keys mode: validateLicenseKey):
const ent = await getEntitlement(req.session.utaAccessToken);
if (ent.entitled && ent.product_public_id === "prod_<your-pro-id>") {
  // serve paid content
} else {
  offerUpgrade(purchaseUrl("<prc-price-id>"));
}

Hosted sign-in itself is two small routes (/login and /callback) — the Quick Start walks that whole loop end to end; keys mode skips both.

Supported Frameworks

Choose your language to see the full list of framework guides, or jump straight to the Quick Start.

Python

Flask, Django, FastAPI, Dash, and Streamlit — sign-in, entitlement gating, and purchase links for each framework.

Explore Python

JavaScript

Express, Node.js, Fastify, Next.js, Nuxt, plus React and Vue — sign-in, entitlement gating, and purchase links for each framework.

Explore JavaScript

Quick Start Sell from your own website Sign in with UseThatApp