Documentation

The mental model behind the Flint API: orders are the center, and payments, checkout, invoices, and subscriptions attach to them.

How test mode works on Flint, why test keys are sandbox-bound, and how to create and reset isolated sandboxes for development, CI, and QA.

How Flint authentication works: the Authorization header, live vs sandbox-bound test keys, and what authentication and authorization errors mean.

How Flint represents money: integer minor units, the amount and currency object, and when to use unit_price_money vs amount_money.

Install and use the official @flintpay/node package for typed Flint Pay integrations in Node.js and TypeScript.

Simulate successful payments, declines, and 3D Secure with test cards, then verify orders, webhooks, refunds, and renewals in your sandbox.

The test-to-production checklist: swap keys, register a live webhook endpoint, confirm readiness, and verify before real money moves.

The order is Flint's durable commerce record; checkout sessions, payment intents, invoices, and payment links are collection surfaces attached to it. What that buys your integration, and when to skip it.

Collect card payments in your own UI with the Stripe Payment Element and Flint's server-confirmed order payments, including 3D Secure.

Create a Flint-hosted checkout for one buyer. Pay an order, charge a quick amount, or start a subscription, then verify the result from your backend.

Create a reusable hosted checkout URL you can share anywhere. Sell products, collect donations, ticket events, and start subscriptions with no frontend code.

Three hosted ways to collect payment, one orders-first engine underneath. Decide in two questions, see the boundaries, and learn how to combine them.

Place a hold on a card with delayed capture, then capture in full or in part, or void to release the hold.

Issue full, partial, and line-item refunds, track them through their asynchronous lifecycle, and handle the ones that fail.

Let buyers add a tip and add your own fees, like delivery and service charges, to an order. Fixed and percent amounts, tax treatment, and how both land in order totals.

Bill a specific customer for a specific amount. Flint emails a hosted payment page, tracks the balance through card, check, and wire payments, and renders the PDF.

Model recurring pricing with plans, sign customers up through hosted checkout or your own UI, and run the full lifecycle. Trials, renewals as orders, failed-payment recovery, pause, and cancel.

Receive signed event notifications when payments, orders, and subscriptions change, verify Standard Webhooks signatures, and process each one exactly once.

Every webhook event Flint can send: what triggers it, what its data payload carries, and which event to build each job on.

Retry any write safely with idempotency keys. How replays, conflicts, key scoping, and the 24-hour replay window work on the Flint API.

Page through any list endpoint with page_size, page_token, and next_page_token. One cursor pattern for every resource, plus sorting, filtering, and how to know when you are done.

Read the Flint error envelope, branch on types and codes, retry safely with idempotency keys, and handle declines as outcomes rather than errors.

How Flint Pay rate limits work: per-key and per-merchant budgets, the anatomy of a 429, safe retry patterns, and how to design an integration that stays under the limits.

Turn a request_id into a diagnosis with request logs and resource timelines that stitch API calls and webhook deliveries together.

How to handle Flint secrets in production: server-side-only keys, source-control hygiene, least-privilege scopes, expiry and rotation, and what to do the moment a key leaks.

Tie every settled dollar back to an order and match a bank deposit to the balance transactions that funded it.

Respond to disputes and chargebacks operationally: monitor via events, meet evidence deadlines, and reconcile the money impact.

Every status value for orders, payments, invoices, subscriptions, and more, plus which transitions are legal.

Migrate common Stripe integrations to Flint for subscriptions, one-time payments, payment links, invoices, saved cards, refunds, and webhooks.

Migrate common Square payment flows to Flint for hosted checkout, embedded card payments, cards on file, subscriptions, invoices, refunds, and webhooks.

Give AI coding agents one URL with Flint Pay schemas, docs, and integration conventions.

Connect an AI coding agent to the Flint docs over the Model Context Protocol for live search and API reference lookups.

Create a Flint merchant and mint the first API key entirely over the API, without the dashboard.

Build an installable Flint partner app, send merchants through hosted OAuth install, exchange install tokens, and subscribe to lifecycle webhooks.