Build on Wrenbase · Issue No. 1
The whole AP/AR engine, behind one API.
Everything Wrenbase does, you can drive from your own code or an AI assistant. Invoices, payments, vendor intake, and the ledger underneath, reachable over REST and MCP. Screening runs on the way in, so nothing skips the checks just because it came from an integration.
POST /api/v1/invoices
{
"contact": "con_8fa2",
"amount": 120000,
"due": "2026-05-28"
}
201 Created
"inv_1042" · draft · screened
Chapter 1 · Two ways in
Compose it with REST or MCP.
You can build your money platform two ways, and both reach the same primitives. Call the REST API from your own code, or drive it through MCP from an AI assistant. The engine, your permissions, and the screening are identical either way.
Build it into your product.
A REST API over invoices, contacts, and the transaction ledger. Send an invoice from your app, record a payment against it, or sync your client and vendor list, all as plain JSON.
developers.wrenbase.com/api/v1
API reference→Let an AI assistant drive it.
An MCP server that hands a compatible AI agent the same tools a person has. Draft an invoice, look up a vendor, check what's outstanding, all through natural instructions, scoped to your permissions.
developers.wrenbase.com/mcp
MCP setup→Chapter 2 · See it in code
Send an invoice in one call.
curl https://developers.wrenbase.com/api/v1/invoices \
-H "Authorization: Bearer wb_live_..." \
-H "Content-Type: application/json" \
-d '{
"contact": "con_8fa2",
"amount": 120000,
"due": "2026-05-28"
}'{ "id": "inv_1042", "status": "draft", "screened": true }Chapter 3 · What you can build
The same primitives our Workspace runs on.
Not a cut-down developer sandbox. The exact objects the hosted app is built from, exposed for you to compose.
Invoices
Invoices, quotes, credit notes, and payment requests are all one resource. Create, update, and transition with a single call.
POST /v1/invoices
Contacts
Clients and vendors share one resource. Filter by role, pull their full history.
GET /v1/contacts?role=vendor
Transactions
The ledger. A payment is a transaction row. Read it for dashboards or your warehouse.
GET /v1/transactions?invoice=
Organization
Who the key acts as, plus aggregate stats for the account.
GET /v1/organization
One mutation verb
Edit a draft or transition its state through the same PATCH. Send, mark paid, or void by writing the status.
PATCH /v1/invoices/{id}
Screened on ingest
Everything that comes in is screened first. The result rides along, read-only, on the record.
GET …/{id} → screening
Chapter 4 · Screening on ingest
An integration can't skip the checks.
Data that comes in through the API goes through the same screening as anything submitted in the app. Sanctions checks and your rules run before a bill lands in your workflow, so a bad payable can't sneak in through the back door just because it arrived over HTTP.
How screening works →Incoming bill from your ERP
$4,200 · [email protected]
Sanctions compliance
Your rules
Sender reputation
Passed · added to your Bills inbox
Chapter 5 · Beyond the raw API
More ways to build on Wrenbase.
Start building on Wrenbase.
Create an account, generate a key, and make your first call.
Common questions
Quick answers.
- What can I build with the Wrenbase API?
- Anything you can do in the app. Create and send invoices, add and manage contacts, record a payment against an invoice, and read the transaction ledger. The REST API exposes the same AP/AR engine the hosted Workspace runs on, so your integration and the app stay in sync.
- What is the MCP server for?
- MCP lets an AI assistant drive Wrenbase directly. Point a compatible AI agent at the MCP server and it can draft invoices, look up a vendor, or check what's outstanding using the same tools and permissions a person would have.
- How does authentication work?
- You create an API key from your Wrenbase settings and send it as a bearer token. Keys are shown once, scoped to your organization, and can be revoked at any time. Data stays isolated to your organization, so a key never reaches another tenant's records.
- Does screening apply to data sent through the API?
- Yes. Anything that comes in through the API, an incoming bill or a new contact, goes through the same screening as data entered in the app. Sanctions checks and your rules run on the way in, so an integration can't quietly push an unchecked payable into your workflow.
- Is there a fee to use the API or MCP?
- There's no separate API fee. You build against the same account and plan you already use. Higher-volume and embedding arrangements are worked out directly with us.
- Can I embed Wrenbase inside my own product?
- Yes. If you're building a platform your customers run their business on, you can offer them invoicing, payments, and vendor intake under your own brand. See Embed & white-label for how that works.