# FastBill MCP Muse connector

From musedirectory.ai, the independent directory of Meta Muse connectors. Not affiliated with Meta.

## FastBill MCP

Read and create FastBill invoices, customers, estimates, expenses and time entries

- Record: https://musedirectory.ai/connector/fastbill-mcp
- Category: Finance & Bills
- Developer: usefulapi (https://usefulapi.io/fastbill/)
- Muse status: Extra setup. Not in Muse's Connectors list yet. Muse can still use it: its page gives you a request to paste into Muse.
- Health: Working, 1368ms, checked 2026-10-29T11:31:00Z
- Endpoint: https://fastbill.usefulapi.io/mcp
- Auth: No account needed; Pricing: unknown
- Screening: Screened, no issues found (2026-10-29T12:36:22Z)
- Source: Found in the official MCP Registry (io.usefulapi/fastbill) https://registry.modelcontextprotocol.io/v0/servers?search=io.usefulapi%2Ffastbill

Connect to FastBill accounting software to view customers, invoices, estimates, expenses and time entries. Create invoices, customers, projects and time entries. Requires FastBill account and API credentials.

Example request: "Show me all unpaid invoices from this month and mark the one from Acme Corp as paid"

How to connect: Not in Muse's Connectors list yet, but Muse can still use it. Paste this into Muse: "Use FastBill MCP to help me. It is a free service with an MCP server at https://fastbill.usefulapi.io/mcp. It does not need an API key. Ask me before you share anything with it." Muse asks before it shares anything with the app's site. Meta does not review apps used this way, so only use ones you trust. We tested this in the Muse app on September 24, 2026: Muse used an app's link directly this way and returned a live answer.

Tools:
- fastbill_list_customers: List customers (name, address, e-mail, VAT id, payment terms and bank details as stored in FastBill). Filter by search term (organization, name, address, zip, e-mail or tags), customer number, country or city. customer.get.
- fastbill_get_customer: One customer by FastBill customer id. customer.get with CUSTOMER_ID.
- fastbill_list_contacts: List contact persons of customers (name, position, e-mail, phone). Filter by customer, search term or contact id. contact.get.
- fastbill_list_invoices: List outgoing invoices, drafts and credit notes with totals, state (draft, unpaid, overdue, paid, canceled), dates and line items. Filter by customer, number, type, date ranges (invoice date, due date, paid date, last update). invoice.get.
- fastbill_get_invoice: One invoice by FastBill invoice id, with all line items, VAT, payments and the document URL. invoice.get with INVOICE_ID.
- fastbill_list_recurring_invoices: List recurring invoice templates (customer, interval data, totals, items). recurring.get.
- fastbill_list_estimates: List estimates (quotes) with state (a created, b sent, c negotiation, d accepted, e rejected, f invoiced), totals and items. estimate.get.
- fastbill_list_expenses: List expense entries (supplier, category, net/VAT/gross, dates, document URL). Filter by invoice number or date ranges. expense.get.
- fastbill_list_revenues: List revenue entries (income booked in FastBill: customer, totals, dates, payments). Takes the same filters as invoices. revenue.get.
- fastbill_list_articles: List products and services (article number, type, title, unit price, VAT, unit). article.get.
- fastbill_list_projects: List projects (name, customer, hourly rate, VAT, start/end date). project.get.
- fastbill_list_time_entries: List work time entries (customer, project, date, minutes, billable minutes, comment, invoice). Without filters FastBill returns the latest entries of the current month. time.get.
- fastbill_list_templates: List the invoice/estimate templates (template id, name, hash). Use a template id with the create tools. Ids change whenever a template is edited. template.get.
- fastbill_create_customer: WRITE: create a customer. customer_type is required; a business needs organization, a consumer needs last_name. Bank details are not accepted by this tool. FastBill does not check for duplicates, so search with fastbill_list_customers first. customer.create.
- fastbill_update_customer: WRITE: update fields of an existing customer; only the fields you pass change. Bank details are not accepted by this tool. customer.update.
- fastbill_create_invoice: WRITE: create an invoice for a customer from line items. FastBill stores it as a draft; it gets its number and becomes final only with fastbill_complete_invoice, and it is never sent by this tool. Check the result with fastbill_get_invoice. invoice.create.
- fastbill_complete_invoice: WRITE, NOT REVERSIBLE: turn a draft invoice into a final invoice. FastBill assigns the invoice number and PDF; a final invoice can no longer be edited (it can only be canceled in FastBill). Nothing is sent to the customer. Only call this after the user confirmed the draft. invoic
- fastbill_set_invoice_paid: WRITE: mark a final invoice as paid, with the payment date and method. invoice.setpaid.
- fastbill_create_estimate: WRITE: create an estimate (quote) for a customer from line items. It is not sent. estimate.create.
- fastbill_create_article: WRITE: create a product or service (article number, title and unit price are required). article.create.
- fastbill_create_project: WRITE: create a project for a customer (name and customer are required). project.create.
- fastbill_create_time_entry: WRITE: book a work time entry on a project (customer, project and start time are required). time.create.

Screening checks:
- MCP handshake: pass (Answered in 10ms)
- Domain against threat feeds (Cloudflare security DNS): pass (fastbill.usefulapi.io, usefulapi.io not flagged)
- Published packages against the OSV malicious-package database: n/a (No npm or PyPI package published)
- Hidden instructions or invisible characters in tool text: pass (22 tools read, nothing found)
- Inputs asking for passwords, card numbers or seed phrases: pass (None found)
- Domain and redirects: pass (No redirects off the domain)
- AI review of purpose and tool behavior: pass (No concerns)