NewsOperate As is live. Send your first client one link
Operate As

Integration

fastbill

German invoicing and bookkeeping: invoices, quotes and receipts. Your client pastes their fastbill key once, and your agent or your code works with their access.

Accounting

About fastbill

Through Operate As, your agent, n8n workflow or code works in fastbill with your client's own access. Your client pastes their API key from fastbill once. We store it encrypted, so it never sits in an email or a shared doc. Your agent reaches any endpoint of fastbill's API through the request tool, with the client's access attached.

Common uses in Accounting

  • Create invoices and record payments
  • Match transactions and chase overdue bills
  • Pull numbers for a monthly report

fastbill

fastbill · Accounting

API key

German invoicing and bookkeeping: invoices, quotes and receipts

The client pastes their API key from fastbill's settings. We store it encrypted.

Tested against fastbill's live API.

Building with fastbill? The docs have setup steps and code for every tool.

Open the fastbill docs

Tools

Your agent calls any endpoint of fastbill's API with the request tool, with the client's access attached.

Base URL for request

https://my.fastbill.com/api

  • request

    HTTPS ANY /v1/clients/{clientId}/fastbill/{path}

    Any endpoint of fastbill's own API, with the client's access attached.

    servicestringrequired
    This service: fastbill
    methodstringrequired
    GET, POST, PUT, PATCH or DELETE
    pathstringrequired
    The path under https://my.fastbill.com/api
    queryobjectoptional
    Query parameters
    bodyobjectoptional
    A JSON body

Over MCP every tool also takes client_id, from list_clients. Over HTTPS send it as clientId to https://api.operate.as/v1.

What the client approves

  • Use the fastbill key you paste, with only the access you gave that key

Related

More in Accounting

Browse every service

Get started

Send your next client one link

Add a client, select the services, copy the link. You'll get an email the moment their access is ready. Start free, no card required. Paid plans are one flat monthly price, and a busy month never takes your agents offline.

Prefer email? hello@operate.as