Overview

OneBooks is a multi-tenant accounting platform, and the developer platform is how your product connects to it — anything from a headless API integration to a full app that runs inside OneBooks and reaches every business in the marketplace. Every OneBooks plan, including Free, includes full API access; nothing here is paywalled from you or from the merchants you connect to.

Two ways to build

	Headless integration	Embedded app
Runs	Your own servers, calling the REST API	Also inside a sandboxed iframe in the OneBooks UI itself
Auth	OAuth 2.0 authorization code + PKCE	The same, plus session tokens + token exchange for the embedded page
Discoverable by merchants	Only if you build your own onboarding	Optionally listed in the marketplace
Start with	Getting started	Quickstart: build an embedded app

Most integrations are headless; pick embedded when merchants should be able to find and open your app without leaving OneBooks. The two aren’t exclusive — an embedded app is still calling the same REST API underneath.

How an integration works

1. A business connects your app through standards-based OAuth 2.0, either a browser redirect (authorization code + PKCE) or, for embedded apps, a one-click managed install. The business owner reviews the scopes you request and approves.
2. You call the REST API with the resulting access token. The token is bound to that one business — every request is automatically tenant-scoped, and you never send a business identifier.
3. OneBooks calls you back: webhooks push document and lifecycle changes in real time, and the Events API gives you the same feed as a pull.

Everything you push lands in a real double-entry ledger: an imported invoice posts the same journal entries as one created in the OneBooks app, and shows up in the business’s P&L, balance sheet and tax reports immediately.

Beyond the REST API

• Embedded apps — a page you host, opened inside OneBooks: on its own home route and at 15 UI extension slots across invoices, customers, the dashboard and more. See Embedded apps.
• App data — typed fields your app owns on a business’s records, visible to the merchant, never touching the ledger. See App data.
• Hosted functions — your own JavaScript, run by OneBooks on events you subscribe to — no server for you to operate. See Hosted functions.
• Marketplace — a reviewed, localized listing that puts your app in front of every OneBooks business; you bill merchants directly and keep 100% of the revenue. See Publishing your app.

Tip

New to the platform’s vocabulary — installation, scope, session token, event, extension, listing? Platform concepts defines all of it on one page.

AI connectors are a different path. Claude, ChatGPT, OpenClaw and custom agents reach a business over MCP, which a business owner connects for themselves from inside the OneBooks app — those clients self-register with the authorization server and are never developer-console apps. This site documents the partner platform; if your integration needs AI features, build them on the REST API described here. See Scopes for the boundary.

Base URLs

Surface	URL
API	https://api.getonebooks.com
Authorization page (user-facing consent)	https://app.getonebooks.com/oauth/authorize
OneBooks app (where merchants — and your sandbox owner — sign in)	app.getonebooks.com (opens in a new tab)
Developer console	developer.getonebooks.com/console
OAuth discovery document	https://api.getonebooks.com/.well-known/oauth-authorization-server
Session-token keys (JWKS)	https://api.getonebooks.com/.well-known/jwks.json
Public app marketplace	getonebooks.com/apps (opens in a new tab)
Merchant help for apps	docs.getonebooks.com/apps/marketplace (opens in a new tab)

Prefer the discovery document over hard-coding endpoints — it lists every OAuth endpoint plus the API base URL.

Start building

Getting startedFrom zero to your first authenticated API call, step by step.

Quickstart: build an embedded appScaffold the starter app, install it into a sandbox, and use it inside OneBooks.

WebhooksSigned event deliveries with automatic retries.

API referenceEvery partner endpoint, request and response schema.

The developer journey

Access to the platform is gated — you build and test first, then go live:

1. Create a developer account and complete the NDA + developer agreement.
2. Create an organization and register your app to get credentials.
3. Build against sandbox businesses — throwaway but fully real OneBooks tenants (up to 3 per organization).
4. Submit for review. Once approved, your app can connect to any OneBooks business.
5. Optionally, publish a listing so merchants can find and install your app in the marketplace — see What merchants see for the journey from their side.

Integration patterns

Not sure how to model your data in an accounting system? The integration patterns guide covers the three most common shapes — POS sales (daily summary vs. per-document push), e-commerce order-to-invoice mapping, and ERP master-data sync — with runnable examples. Building something merchants open inside OneBooks itself? See the embedded app quickstart and Platform concepts instead.