For developers

Build apps for the businesses that run on OneBooks

An OAuth API and MCP, pages embedded right inside OneBooks, app data on real records, and hosted functions — reach every OneBooks business through one reviewed marketplace listing.

Create a developer account Read the docs

See what merchants see

What you can build

Four ways to extend OneBooks

OAuth API & webhooks

A scoped OAuth 2.0 REST API over invoices, payments, customers, reports and more, plus MCP for AI agents. Get 40+ events by webhook or from the Events API — with idempotent writes, dated versions and full reference docs.

Apps inside OneBooks

Your own pages inside OneBooks, plus actions and cards in 15 places — the dashboard and seven kinds of record, from invoices to purchase returns — in a sandboxed frame, authenticated with short-lived session tokens.

App data on records

Store your own typed fields on 12 kinds of record — customers, invoices, items and more — shown to the merchant right on the record, where they already work.

Hosted functions

Run your code on events in an isolated sandbox on OneBooks' infrastructure. It can reach only the hosts you declare — and there's no server to operate for simple automations.

Show me the code

From embedded page to ledger data

App Bridge hands your embedded page a short-lived session token. Your server exchanges it for an access token — then it's an ordinary API call. No redirect, no SDK required.

Read the token-exchange guide (opens in a new tab)

1 · Exchange the session token, on your server

curl -X POST https://api.getonebooks.com/oauth/token \
  -u "YOUR_CLIENT_ID:YOUR_CLIENT_SECRET" \
  -d grant_type=urn:ietf:params:oauth:grant-type:token-exchange \
  -d subject_token=SESSION_TOKEN \
  -d subject_token_type=urn:ietf:params:oauth:token-type:jwt

2 · Call the API

curl https://api.getonebooks.com/invoices \
  -H "Authorization: Bearer ACCESS_TOKEN"

Why build on OneBooks

Built for developers who ship

✓ Every plan — including Free — includes API access, so every merchant can install your app
✓ Five languages including Arabic, fully right-to-left
✓ A reviewed marketplace listing, with distribution inside the app every merchant already uses
✓ Free sandbox businesses to build and test against, with no risk to real books
✓ You bill your customers directly and keep 100% of your revenue
✓ Rate limits per app and per business, so other apps' traffic never eats into yours
✓ Date-based API versioning, with 12 months of support after each new version

How it works

From idea to the marketplace

Create a developer account

Build in a sandbox

Pass app review

Until it's approved, your app can connect only to your own sandboxes. App review checks it before real businesses can use it.

Pass listing review

Submit your marketplace listing. Once listing review approves it, it's published — and every OneBooks business can find and install your app.

See what merchants see

Security & trust

Least privilege, by default

✓ Embedded pages run in sandboxed, cross-origin iframes, authenticated with short-lived session tokens — never a shared cookie
✓ Every install is scoped to exactly the permissions it asks for, consented by the merchant, and nothing more
✓ Hosted functions run in isolated workers with a declared, enforced list of hosts they can reach
✓ Every write your app makes is attributed to it in the merchant's audit log
✓ Merchants can uninstall your app any time — access ends immediately, everywhere

SDKs & tools

Ship faster with the official tools

App Bridge

The browser library for embedded pages: session tokens, navigation, toasts, pickers and confirmation dialogs.

Node SDK

A typed server client for the OAuth API, with retries, token exchange, and session-token and webhook verification.

Functions SDK

Types for writing hosted functions, plus a local runner to test one before you deploy it.

CLI

Scaffold an app, deploy and test hosted functions against a sandbox, and push new versions from your terminal.

Starter template

A runnable embedded app the CLI scaffolds for you — OAuth, App Bridge, an invoice action and card, a webhook receiver and a sample hosted function, already wired up.

The SDKs and CLI are in preview — install them from source until they're published to npm.

Start building

Your app, in front of every OneBooks merchant.

Create a free developer account, build against a sandbox, and publish to a marketplace merchants already trust.

Create a developer account Read the docs